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Inside Unit 731, Japan's Gruesome WWII Human Experiment Program

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Key Takeaways

• Unit 731, a Japanese Imperial Army program, conducted deadly medical experiments and biological weapons testing on Chinese civilians during WWII.
• Thousands of prisoners were killed in cruel experiments, and perhaps hundreds of thousands more died from biological weapons testing.
• The true extent of Unit 731's actions was shielded from public knowledge for years, with the U.S. granting immunity to top officials in exchange for research.

For years after World War II , in most of what was considered the "civilized" world, the truth behind Japanese Imperial Army Unit 731 was quietly swept away. Facts were suppressed. Memories questioned. Reports denied.

Even today, the true extent of Unit 731's wartime actions — horrendous, deadly medical experiments and lethal biological weapons testing on unsuspecting Chinese civilians — is known largely only to historians and scholars.

But the facts are out there for those who seek them. And for those who seek to use them for their own personal reasons.

"I think that it has become a piece of this tortured dialogue over the war between Japan and China. The Chinese have seized upon this quite a bit. And the Japanese right, the nationalist right, their basic view is that, 'Oh, the Chinese. This is all political.' ... And there is a certain truth to that," says Daniel Sneider , a lecturer in international policy at Stanford's Freeman Spogli Institute for International Studies . "There is a 'uses of the past' question here. Perhaps you could say it's cynical in that everybody does it."

The truth is that Japan's Unit 731 committed some of the most heinous war crimes ever. Thousands of prisoners were killed in cruel human experiments at Unit 731, which was based near the northeastern China city of Harbin, north of the Korean peninsula and on a border with Russia. Perhaps hundreds of thousands more — maybe as many as a half-million — were killed when the Japanese tested their biological weapons on Chinese civilians.

The exact number of dead is not known. It may never be known.

"It's very difficult to calculate," says Yue-Him Tam , a history professor at Minnesota's Macalester College and co-author of a book entitled, " Unit 731: Laboratory of the Devil, Auschwitz of the East (Japanese Biological Warfare in China 1933-1945) ." Tam, born and raised in China, has taught a class at Macalester on war crimes and memory in contemporary East Asia for more than 20 years. "If you include those victims who suffered from the other activities — not necessarily just used as human guinea pigs — the bombs in China ... it's very difficult to calculate."

The Start of Unit 731

America's shameful part, dealing with unit 731 today.

Unit 731 — its official name was the Epidemic Prevention and Water Purification Department of the Kwantung Army — was formed before World War II began (at least for the U.S., which didn't officially enter the war until December 1941). It came about sometime in the mid-1930s when Japan and China went to war , a conflict that eventually morphed into World War II's war in the Pacific theater.

The Unit's charge was clear from the beginning: testing, producing and storing biological weapons. Such activities were outlawed by at least two international treaties at the time, though the Japanese did not ratify the 1925 Geneva protocol . It didn't matter.

From the start, Unit 731, under General Shirō Ishii , was merciless.

Among the thousands of experiments conducted on prisoners: vivisections without anesthesia; injections of venereal diseases to examine their spread; amputations to study blood loss; removal of other body parts and organs; starvation; and deliberate exposure to freezing temperatures to examine the effects of frostbite . From a 1995 article in The New York Times , relating a story from a medical assistant in Unit 731:

Reportedly, not one of the thousands of prisoners that were experimented on — most of whom were Chinese, though many were Russian or Korean — survived.

Later, the Japanese took especially virulent forms of the plague and other pathogens that were developed at Unit 731, put them in canisters and dropped them on nearby towns to see if their weapons would work. They did.

Thousands of these still-dangerous bombs remain in the Chinese countryside today, Tam says. Some people still suffer from the Japanese "dirty" bombs.

At one time, the Japanese hatched a plan to infect fleas with a plague manufactured at Unit 731 and drop flea-filled bombs, launched from planes stored aboard submarines, on San Diego in a mission code-named Operations Cherry Blossoms at Night . The war ended before the plan could be executed.

After the U.S. dropped atomic bombs on Japan and effectively ended the war in 1945, Japanese leaders ordered the destruction of Unit 731, which included more than 150 buildings and two airports. As the victorious Allied forces approached, many hundreds of remaining prisoners were killed. The thousands of people who worked in the place and conducted experiments on healthy, living humans scattered, many never to face justice.

The top doctors and soldiers at Unit 731 kept careful records of their experiments, and used them to leverage their way to freedom after the war. When the Allies swept into China, they agreed to grant Ishii and many of his associates immunity from prosecution for war crimes . The reasons: The U.S. wanted Unit 731's research for its own use , and it wanted to keep that information out of the hands of others, including the Russians. Thus, for years, the true nature of what went on in Unit 731 was shielded from public knowledge.

Some of the truth came out in the Khabarovsk War Crimes Trial , held in that Russian city in December 1949. Twelve members of Unit 731 and associated units were tried. All were found guilty and imprisoned. Despite that trial, though, much of what went on in Harbin was immediately classified by the U.S. government and remained clouded in secrecy.

More details about Unit 731 are still being unearthed. A confession from a unit commander, written to U.S. interrogators at a base in Maryland shortly after the war, was released in August 2021 by a Chinese provincial agency. Chinese and Russian news outlets heralded the release, which highlighted America's part in using the information gathered by Unit 731, hiding it and protecting its sources from further prosecution.

"The United States is not the outsider to this. Previously, I think the tendency was for the people in the United States to think, 'This is a problem between Japan and its neighbors.' But not only were we of course the major combatant in the war, we shaped the postwar settlement, including decisions like the one concerning Unit 731," Sneider says. "We made the big decisions about what was a war crime and what wasn't ... We're the creator of the postwar order, and therefore we have responsibility and involvement in dealing with the issues that were left, unfortunately, unresolved."

Research on 731 continues to be conducted all over the world. As recently as 2018, the Japanese government provided a list of more than 3,600 members of Unit 731 to a Japanese scholar. Yet even with more information, with politicians and the governments of various countries opening their records, the facts remain largely in the shadows and in some dispute.

In China, with the resurgent government now not as dependent on Japan as it was in the years following World War II, the Chinese are demanding more answers, eager to hold old rival Japan responsible.

For their part, most Japanese are not nearly as willing to engage in discussions about what is considered by many Japanese as a shameful period in that country's history. Some say the surge in Chinese interest in Unit 731 is nothing more than political in nature.

The U.S. is dealing with its own internal demons about its history with Unit 731.

These varying viewpoints, and others in the region and throughout the world, complicate matters. From 2006 to 2016, Sneider and others at Stanford's Walter H. Shorenstein Asia-Pacific Research Center conducted a project, " Divided Memories and Reconciliation ," aimed at examining the historical memory of the wartime period in Asia. These histories, viewed differently, go directly to ideas about national identity and nationalism. They are tricky histories to examine, uncovering differences that often stay unresolved.

"Sometimes the truth is pretty elusive," says Sneider. "To some degree, the goal is not necessarily always to establish 'the fact.' That's a good goal, but it may not be possible. The goal, if you're seeking reconciliation, the goal may be to understand the different perceptions of the other.

"In Japan, wartime memory is highly contested within Japan. They've been battling over these issues since 1945. Sometimes it's important just for Koreans and Chinese and Americans to understand what's going on within Japan. That path is contrived; to try to get to reconciliation by agreeing on what happened."

People may not agree on how many people were killed by the criminals in Unit 731, who did it, how it was done, or why it occurred. They can, and should, look critically upon America's decisions after the war, too.

But this much is indisputable: What happened in Unit 731 was an abomination.

In August 2015, The Museum of Evidence of War Crimes by Japanese Army Unit 731 opened in an area just south of Harbin, a city of more than 5 million people. Tam is among the millions who have visited the site.

"The room where they experimented with poisonous gas, there are still walls standing there, and the walls are really thick, almost like 1-meter [3.2-feet] thick, to prevent leaking of something. When I saw these things, I was really shedding tears as to how people can do that," Tam says. "It was very moving.

"I am a historian. The most important thing that matters to me is the facts. I want to find out the facts. And that was a fact, Unit 731. The crimes they committed and produced are facts."

Japanese war criminals were tried at the International Military Tribunal for the Far East , otherwise known as the Tokyo War Crimes trial. Testimony from Ishii , gathered in Maryland after his postwar arrest, was used in the trial, too. But Ishii, the architect behind the Unit 731 atrocities, was never charged. He died in Tokyo in 1959, a free man.

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Japan’s Hellish Unit 731

In conquered Manchuria, ghastly experiments were fiendishly conducted on human guinea pigs.

This article appears in: Fall 2018

By David D. Barrett

The final months of World War II saw the liberation of hundreds of ghastly concentration camps and the awful reality of Nazi racism. For more than seven decades those atrocities, including the use of human beings for medical experiments, have been common knowledge. Far less known is the wholesale slaughter of hundreds of thousands of Chinese by a Japanese organization known as Unit 731.

Established for the purpose of developing biological and chemical weapons, Unit 731 exceeded by a year the duration of the Third Reich. While biological and chemical weapons were not new to warfare, Japanese testing on human subjects was unparalleled even by the Nazis.

What makes this descent into barbarity all the more stunning was the Japanese contribution to medical science just three decades earlier. A U.S. Army doctor named Lewis Livingston Seaman observed colleagues who were attending to the Imperial Japanese Army (IJA) during the Russo-Japanese War (1904-1905).

Dr. Seaman came away from his experience profoundly impressed with his medical brethren, stating, “The history of warfare for centuries has proven that in prolonged campaigns the first, or actual enemy, kills 20 percent of the total mortality in the conflict, whilst the second, or silent enemy (disease), kills 80 percent.

“I unhesitatingly assert that the greatest conquest of Japan has been in the humanities of war, in the stopping of the needless sacrifice of life through preventable disease. Japan is the first country in the world to recognize that the greatest enemy in war is not the opposing army, but a foe more treacherous and dangerous—preventable disease, as found lurking in every camp—whose fatalities in every great war of history have numbered from four to twenty times as many as those of mines, bullets, and shells.

“It is against this enemy that Japan, with triumphant exaltation, may cry Banzai. For it is against this enemy that she has attained her most signal victories….”

Twenty years later, Japan signed the Geneva Convention, which prohibited biological and chemical warfare. But where other men reasoned with justification that these kinds of weapons should be banned by civilized nations, another man, a specialist in bacteria and related fields, Dr. (Colonel) Shiro Ishii, saw the prohibition as an opportunity.

He reasoned that if something were bad enough to be outlawed, then it must certainly be effective, and he began a sustained effort to establish a military arm within the Japanese Army whose aim would be the development of weapons based on biology. Ishii was highly intelligent but arrogant, merciless, and immoral.

He thought of himself beyond reproach and as a visionary. He was driven to break new scientific ground and to help Japan defeat its foes. In his quest to contribute to that effort, Ishii in time exhorted his team of physicians to violate the physicians’ ethical code: “A doctor’s God-given mission is to challenge all varieties of disease-causing micro-organisms; to block all roads of intrusion into the human body; to annihilate all foreign matter resident in our bodies; and to devise the most expeditious treatment possible….

“However, the research we are now about to embark is the complete opposite of these principles, and may cause us some anguish as doctors. We pursue this research for the double medical thrill; as a scientist … probing to discover the truth in natural science; and as a military person, to build a powerful military weapon against the enemy.”

To convince the senior levels of the Imperial Army to back his efforts, Ishii built his case around financial considerations, completely skirting either Japan’s obligation to the world community as a signatory of the aforementioned 1925 Geneva Convention or the morality of using such weapons. Ishii argued that compared with the costs of building, manning, and maintaining huge conventional forces, bacteria and gas were a far less expensive alternative.

By 1930, nationalism burned hotter than ever in Japan and created a climate receptive to Ishii’s ideas of developing biological weapons. In September 1931, Japanese forces instigated the “Mukden Incident.” The pitched battle between Japanese and Chinese forces was actually no more than a Japanese ruse used to justify a complete takeover of Manchuria.

Moreover, the area became the perfect place to develop and test Ishii’s new biological and chemical weapons, a place where he would be free to conduct any kind of experiment he deemed beneficial.

The following year, under the cover of the euphemistically named Epidemic Prevention Research Laboratory, Ishii set up shop in the Army’s hospital in Tokyo. The location was only temporary because, to accomplish his objectives, he would need access to far greater resources; Japanese ascendancy in Manchuria provided its medical community unprecedented opportunities for research (much as the Germans used concentration camps and their prisoners for their own medical and pseudo-scientific research).

Ishii’s goal of turning bacteria and gas into weapons for the Imperial Japanese Army required comprehensive study, and he believed animals could not supply usable data. Japan’s control over Manchuria delivered research materials in the form of people who were plucked from the streets and locked into black vans known as voronki (ravens), to be carried off to the waiting prison cells of Unit 731.

Japan’s Kempeitai, the military police arm of the IJA from 1881 to 1945, was tasked with these kidnappings. The Kempeitai was less a conventional military police body than a secret police force akin to the Gestapo. Headed in Manchuria by Hideki Tojo, from 1935 to 1937, the Kempeitai’s cruelty was notorious in occupied territories. (See WWII Quarterly, Fall 2011). After the war, the U.S. Army estimated it numbered 36,000 regular members.

Anxious to take operations to the next level, in 1932 Dr. Ishii chose the city of Harbin, capital of Heilongjiang Province in southwest Manchuria, as the site of Unit 731’s first biological and chemical weapons facility. The original buildout covered a 500-square-meter area and was designated a restricted military zone. A tract of land to the south of the sector was appropriated and made into an airport. It and a nearby rail line were also used to move victims to Unit 731 and transport results and specimens back to Japan’s medical community.

Japan’s medical institutions enabled the work of Unit 731 by supplying Dr. Ishii with top Japanese scientists and physicians who would be labeled Hikokumin (traitors) if they refused to take part. Most medical professionals saw their work as noble service to the Emperor; the fact that they were killing non-Japanese meant nothing to them.

Unit 731 received state-of-the-art equipment and a nearly unlimited supply of funds from the Japanese government. Even for reluctant researchers Ishii’s factories were luxurious. The annual budget for Unit 731 was ten million yen (about nine billion yen in the modern currency, or about $86 million). Salaries were very generous, and the food was exceptional.

Precipitated by an escape attempt by 40 prisoners, all of whom were captured and killed, the Harbin operation was closed and moved to the Harbin suburb of Ping Fang in 1936. This complex was a sprawling walled city of more than 70 buildings that dwarfed its predecessor in Harbin. The perimeter at Ping Fang incorporated more than six square kilometers and rivaled Auschwitz-Birkenau in size. Tucked away inside the administration building was a prison that housed 500 men, women, and children selected for vivisection.

As immense as Ping Fang was, Unit 731 also had affiliated locations in Nanking (Unit 1644), Beijing (Unit 1855), and Changchun (Unit 100). Altogether there were 26 known killing laboratories, experimental detachments, and battalions of the Army spread across occupied lands in Asia. The total number of personnel involved reached some 20,000. All units and facilities were coordinated by the Epidemic Prevention Research Laboratory under the control of Colonel Ishii.

The research was made available not just to the Army hospital in Manchuria, but to doctors and educators throughout Japan. In this way, Unit 731 was performing the service of human experimentation for the entire Japanese medical community, in an on-going feedback loop. “Medicine itself must become a weapon,” said Nakagawa Yonezo, Professor Emeritus at Osaka University.

The gruesome professionalism of Unit 731 included a touch of sardonic humor. The construction of the Ping Fang installation prompted locals to ask what it was. The answer was a “lumber mill.” Regarding this reply, one of the researchers joked privately, “and the people are the logs.”

From then on, the Japanese term for log, Maruta, was used to speak of the prisoners whose last days were spent being infected with lethal pathogens, torn apart, frozen, or gassed by Japanese researchers. The expression indicates a degree of racism far beyond disdain; it is evidence of a belief that torturing the Chinese was of no more consequence than squashing a bug.

As noted earlier, the primary objective of Ishii and Unit 731 was the creation of biological and chemical weapons. To facilitate that end, wholesale human experimentation was utilized, including the vivisection of thousands of people. The justification for performing all these surgeries came from the expectation that human tests would create better weapons.

Doctors in Unit 731 examined the first stages of disease on organs. A former member of Unit 731 described the process: “As soon as symptoms were observed, the prisoners were taken from their cells and into the dissection room, he was stripped and placed on a table, screaming, trying to fight back. He was strapped down, still screaming frightfully. One of the doctors stuffed a towel into his mouth, then with one quick slice of the scalpel he was opened up.” Witnesses reported that, without anesthesia, the victims let out horrible screams when the first cut was made and that the cries stopped soon thereafter.

A doctor at Ping Fang testified to a time when he was working on a pregnant female victim who awoke from anesthesia while being vivisected. The woman said, “It’s all right to kill me, but please spare my child’s life.” It is likely that more than one mother voiced, as a last wish on the vivisection table, the wish to let her child live. None ever did. The researchers wanted their data.

As ghastly as these procedures were, vivisections were not limited to weapons development, but fell into four categories: (1) intentional infection of diseases, (2) training newly employed army surgeons, (3) trials of nonstandardized treatments, and (4) discovering the limits of human tolerance to pain and stress.

Under the auspices of weapons development and intentional infection of diseases, prisoners were injected with various biological agents including plague, typhus, cholera, anthrax, and syphilis.

To test the effectiveness of dispersion methods for military purposes, victims were staked to crosses with their vital organs and heads protected. Various types of bombs and agents were then dropped or sprayed from specially modified planes to test the survivability of the agents and their ability to infect the subjects. Community water and food sources were also contaminated. To determine the results, mobile vivisection units were set up in the field near the infected communities.

The Imperial Japanese Army also allowed its physicians to perform vivisections on living subjects to train them in the treatment of battle wounds—procedures that are too gruesome to describe in detail.

Tests that could have real medical value were also conducted, such as finding the best method to deal with frostbite. But even here Japanese doctors chose to perform the experiments in the most merciless ways possible.

Conventional weapons tests were also carried out. Victims were tied to stakes and used to determine the operational range of flamethrowers, grenades, and various kinds of shells and bombs.

But this was hardly the extent of the tests to which the prisoners were subjected. Sheldon Harris, author of Factories of Death, stated, “They just killed people with no inherent purpose other than to see how they reacted to being killed.” People were locked into high-pressure chambers until their eyes popped out, or they were put into centrifuges and spun to death.

Other experiments involved hanging prisoners upside down to discover how long it took for them to choke to death or injecting air into their arteries to test for the onset of embolisms. Another test consisted of taking blood samples, at least 500 cm³ (slightly more than a pint) at two- to three-day intervals. Some victims became debilitated; still, the blood drainage continued.

When the human guinea pigs could no longer serve as lab material, they were abused in various manners: injected with poison, killed for their vital organs (brains, lungs, or liver), subjected to violent surgeries (e.g., amputation and reattachment of the limbs to the opposite sides of the body, resection of the stomach to attach the esophagus to the intestines). Electrical shocks were administered until the person slowly roasted to death.

Some experiments had no medical purpose whatsoever except the administering of indescribable pain, such as injecting horse urine into prisoners’ kidneys. The doctors of Unit 731, like the Nazi doctors at Dachau and Buchenwald, indulged any perversion they could imagine.

In 1938 and 1939, the Soviet and Japanese Armies clashed in two encounters near the border of Mongolia and Manchuria. The 1939 summer battle, known as the Nomonhan Incident and the Battle of Kalhin Gol by the Soviets, resulted in the overwhelming defeat of the Japanese Kwantung Army by Stalin’s Red Army.

The clash saw the first field operation of Japan’s biological warfare unit; it occurred in a desert region where water was scarce. To disable their Russian foes, the Japanese dumped large quantities of intestinal typhoid bacteria into the river.

Fortunately for the Russians, this type of typhoid germ became ineffective almost immediately after hitting the water. The contamination was probably initiated more for the publicity than anything else, as Ishii likely knew it would not work.

In 1940, Japanese planes dropped wheat, corn, rags, and cotton infested with bubonic plague on the unarmed village of Ningbo, China. More than 100 people died within a few days of the attack.

Two years later, the Japanese conducted a second attack in the same area. Japanese researchers took over a house on top of a hill about a kilometer away from the infected zone to use as a vivisection laboratory. As a result of the attacks, the Ningbo region remained sealed off until the 1960s.

During the siege of Bataan in the Philippines in March 1942, the Japanese planned to release 200 pounds of plague-carrying fleas—about 150 million insects—in each of 10 separate attacks. However, by the time the assault was ready the battle had already ended.

In June-July 1944, during the Battle of Saipan, plague-infested fleas were again to be used against U.S. forces. Fortuitously for the Americans, by this stage in the war it had become almost impossible for the Japanese to get any reinforcements and or matériel to its island bastions, and the Japanese submarine carrying the fleas was sunk en route.

For the Battle of Iwo Jima, February-March 1945, another biological attack was to be carried out against the invading Americans. Two gliders loaded with pathogens were to be towed over the battlefield and released. The gliders never reached their destination.

One of the least known Japanese efforts to attack Canada and the continental United States occurred in late 1944 and the spring of 1945. Records uncovered in Japan after the war indicated that about 9,000 balloon bombs, known as fugo, and carrying incendiary bombs, were launched into the jet stream during this period. More than 200 ultimately reached the United States. Six people were killed in Oregon when a bomb detonated on discovery. Before Japan surrendered, Ishii and Army leaders proposed using balloon bombs filled with cattle plague and anthrax.

As part of Japan’s defense of Okinawa in the spring of 1945, Unit 731 had developed plans to meet the American invaders with plague bacteria. The attacks were never carried out because once again fleas carrying the plague could not be delivered to the island. The native Okinawan population only learned of this plan in 1994.

Operation PX, aka Cherry Blossoms at Night, were the codenames for the Japanese plan for a biological attack on cities in southern California. The plan was completed March 26, 1945, and scheduled for September 22, 1945, but was abandoned due to the strong opposition of Army Chief of Staff General Yoshijiro Umezu, who was also a member of Prime Minister Suzuki’s war cabinet.

The plan involved the use of five I-400 submarine aircraft carriers, each carrying three Aichi M6A Seiran floatplanes launched against San Diego, Los Angeles, and/or San Francisco. The aircraft were to spread bubonic plague, cholera, typhus, and dengue fever over the city, while the submarine crews infected themselves and ran ashore in a vast suicide mission.

Even after surrender, the Japanese considered a final use of biological weapons. Ishii wanted to stage suicide germ attacks against occupying U.S. troops in Japan. This planned attack never took place, once again due to opposition from General Umezu and Vice Chief of the Imperial Japanese Army General Staff, General Torashiro Kawabe, who claimed that he did not want Ishii to die in a suicide attack.

Almost as soon at World War II ended, a new Cold War began between the United States and the Soviet Union. In this atmosphere, Lt. Col. Murray Sanders of the United States Army recommended to General Douglas MacArthur and President Harry Truman in the fall of 1945 that Ishii and his subordinates be given immunity from prosecution as war criminals in return for Unit 731’s research.

MacArthur and Truman approved the deal, and Japan’s biological and chemical weapons program remained largely a secret until the 1990s.

From start to finish, the highest levels of the Japanese government and military were involved in Unit 731. Hideki Tojo, head of the Kempeitai in Manchuria from 1935 to 1937, became Japan’s longest serving prime minister in World War II, from October 18, 1941, to July 22, 1944. Tojo approved the attack on Pearl Harbor and was tried as a Class A war criminal and hanged in 1948.

General Yoshijiro Umezu, who served as the Army’s chief of staff, was a member of the elite war cabinet that held the reins of power in Japan from April 1945 until it surrendered to Allied forces on September 2, 1945. According to Lt. Gen. Kajitsuka Ryuji of the Japanese Medical Service and former Chief of the Medical Administration for the massive Kwantung Army (located in Manchuria), Ishii was given permission to begin the Ping Fang experiment in 1936 by “command of the Emperor.”

At some point in 1939-1940, Hirohito issued still another decree recognizing Ishii’s unit for its service. Moreover, the Emperor’s younger brother toured Unit 731’s facilities during its time of operation.

Unit 731 was extremely well funded, with state-of-the-art facilities, generously staffed with the cream of Japan’s medical community, and routinely communicated with the medical establishment back in Japan—which even provided suggestions for experiments and regularly received human samples.

The vast majority of Ishii’s staff walked away from their wartime service scot free. Information turned over to the United States proved worthless to the American biological weapons program, as the vivisection of human beings did not yield better scientific data.

Immune from prosecution as war criminals, many of Unit 731’s doctors went on to prominent careers in universities, hospitals, and industry, rising to positions that included governor of Tokyo, president of the Japanese Medical Association, and head of the Japanese Olympic Committee. The ringleader, Dr. Shiro Ishii, quietly returned to private practice and died in 1959 of throat cancer at the age of 67.

The Soviet Union was the only government to bring anyone associated with Unit 731 to trial. In late December 1949, in Khabarovsk, Russia, 12 former physicians, officers, and staff were accused of manufacturing biological and chemical weapons. While there was some coverage in the American press, the United States government, keen on protecting its secret deal, labeled the proceedings just another Soviet show trial.

It would take nearly 50 years before the infamy of Unit 731 came to light in the United States. Unlike the Nuremberg and Tokyo trials, in which high-ranking German and Japanese officials were hanged or sentenced to life in prison, the Khabarovsk trials saw no sentence exceed 25 years—with some as short as two. All of the defendants were quietly freed and slipped back to Japan by 1956.

In 1998, more than 100 Chinese plaintiffs filed suit in Japan in an effort to get the Japanese government to acknowledge the crimes of Unit 731 and to obtain reparations for the victims and their families. Mere months before the trial began, the Japanese Education Ministry approved a textbook glossing over the Imperial Japanese Army’s culpability.

The Tokyo District Court’s ruling, coming on August 28, 2002, accepted that Unit 731 had waged germ warfare in China and caused harm to residents but dismissed the Chinese plaintiffs’ claim for compensation. Nevertheless, it was the first time a Japanese court admitted that the Imperial Army had used biological weapons during its war with China from 1932-1945.

Judge Iwata said in handing down the ruling, “The evidence shows that Japanese troops, including those from Unit 731, used bacteriological weapons under the order of the Imperial Japanese Army’s headquarters and that many local residents died.” Noteworthy in the judge’s declaration was his understatement that “many local residents died.”

The judge’s comment was, however, consistent with much of the narrative written about Unit 731 after the war, which generally characterizes the group’s activities as “experimental,” a seeming reference to the vivisections conducted by the Japanese doctors.

Most accounts reckon the loss of life caused by vivisection to be around 3,000 to 10,000 individuals. These figures neglect the field tests of pathogens conducted against Chinese civilians and the subsequent losses of life from bubonic plague after the war.

Such minimization constitutes a miscarriage of justice for the hundreds of thousands who were murdered as a result of these attacks, and potentially the tens of thousands more Americans who could have died if the Japanese plans had been carried out on numerous Pacific battlefields, or if they had been successful in their attempts to deliver biological agents to the U.S. mainland in the latter stages of the war.

As it stands, Sheldon Harris’s Factories of Death (1994) estimates the loss of life at 200,000, with Daniel Barenblatt’s A Plague Upon Humanity (2008) putting it as high as 580,000.

At what point is Unit 731 indicted for mass murder? While some Japanese scholars have been rigorous in documenting Japan’s war crimes, their own government has been unwilling to acknowledge the atrocities it perpetrated against China.

Unit 731’s legacy is one of a useless, fanciful, extravagant, and sadistic indulgence that accomplished nothing politically or militarily for Japan, and, in terms of its research, nothing for the United States.

One can only hope that the perpetrators, who escaped prosecution as war criminals, achieved something positive in their postwar careers because the victims are still crying out for justice.

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December 10

1936–1945: Unit 731 — the Asian Auschwitz

Japanese Medical Atrocities

1936–1945: Unit 731 — the Asian Auschwitz — was a massive biological warfare research program of the Japanese Imperial Army under the command of Lt. General Dr. Ishii Shiro in Pin Fang, Manchuria outside the city of Harbin. Its true purpose was masked as the Epidemic Prevention Research Laboratory. Unit 731 was housed within 150 buildings with a staff of 3,000. It included an aerodrome, railway line, barracks, dungeons, laboratories, operating rooms, crematoria, cinema, bar and Shinto temple. Its barbarous inhumane experiments rivalled the infamous Nazi death camp of Auschwitz-Birkenau, though the numbers of prisoners were smaller, it operated for a much longer period. From 1936 to 1942 between 3,000 and 12,000 men, women and children were subjected to unspeakable diabolical experiments, vivisected while still alive, before they were slaughtered in Unit 731. (C. Hudson, Doctors of Depravity , 2007; Nightmare in Manchuria, 2012; Unit 731 )

Shiro Ishii’s extensive deadly human experiments were under the protection of the Kanto Army High Command, the Kampeitei (secret Japanese police), and local police collaborators. His first laboratories were in the city of Harbin, later in Beiyinhe, and still later in an extraordinary facility in Harbin’s suburb known as Ping Fang.  Construction began in 1936, and was completed in 1939. Originally named Togo, later changed to Ishii Unit, finally it was named Unit 731; it was the world’s largest premier biological and chemical warfare research center.

“Each year hundreds of prisoners were fodder for fiendish experiments.  They were exposed to every known disease.  These ranged from anthrax to yellow fever.  Some were used for hyperthermia experiments.  Others were forced to endure gangrene experiments; and still others were forced to engage in sexual intercourse with individuals known to be infected with venereal diseases. They were then monitored as the disease took its toll on the victims.” “The victims were captured communist partisans, ordinary criminals, political dissidents, those who were mentally handicapped but physically fit, and, when candidates among these groups were scarce, the secret police would pick up the poor, the homeless, off the streets in cities throughout occupied China and Manchuria.  The police would be given orders to send prisoners to Harbin/Ping Fan by “Special Delivery.” “Everyone engaged in this sordid business understood that “Special Delivery” was the code words for new human experimental prey.  Prisoners to be tested were of various nationalities.  The overwhelming majority were Han Chinese.  However, Koreans, Soviet prisoners of varying ethnic backgrounds, and, occasionally, Europeans and Americans were used.” “Victims were frequently vivisected while still living.  They were not given an anesthesia since Ishii and his colleagues wanted to be certain that their tests were not influenced by an outside source.  Those individuals whose experiments required a course of study usually lasted about six weeks.  Then, of no longer any value to the researchers, they were “sacrificed”, the euphemism used instead of “killed.”  The bodies, men, women, and children, would then be dissected by pathologists, and, eventually, deposited in either large burial pits or burned in the three crematoria housed at Ping Fan.” (Sheldon Harris. Japanese Medical Atrocities in WWII: Unit 731 Was Not An Isolated Aberration .” A paper read at the International Citizens Forum on War Crimes & Redress, Tokyo, Dec. 11, 1999)

Unit 731 was divided into eight divisions: Division 1: Research on bubonic plague , cholera , anthrax , typhoid and tuberculosis using live human subjects in a prison was constructed to contain around 300 to 400 people. Division 2: Research for biological weapons used in the field, in particular the production of devices to spread germs and parasites. Shiro Ishii, the mastermind behind Japan’s biological warfare — “Factories of Death” — was a brash and flamboyantly corrupt man who considered himself a visionary” beyond scruples. He was brilliant, charming, intimidating, stone-hearted, driven to break new scientific ground and to help Japan defeat its foes. Ishii exhorted his team of physicians to violate the physicians’ ethical code:

“A doctor’s God-given mission is to challenge all varieties of disease-causing micro-organisms; to block all roads of intrusion into the human body; to annihilate all foreign matter resident in our bodies; and to devise the most expeditious treatment possible. . . However, the research we are now about to embark is the complete opposite of these principles, and may cause us some anguish as doctors.” “We pursue this research,” he explained, “for the double medical thrill; as a scientist . . . probing to discover the truth in natural science; and as a military person, to build a powerful military weapon against the enemy.” (Patrick Fong. Impunity Of Japan’s Secret Biological Warfare Unit , 2000.)

Unspeakably cruel and ghoulish experiments were conducted by Japanese physicians who had been recruited from Japan’s leading academic medical institutions. Like their Nazi counterparts, Japan’s physicians perverted the essence of medicine. Doctors in the biological war program turned life – biology – against life.

They referred to the prisoners as Maruta (“logs” whose killing was comparable to cutting down a tree). Army surgeons conducted many vivisections “for training purposes” — in truth, to desensitize them. The victims were mostly Chinese — men, women, and children, including pregnant women and infants. Soviet, Australian and several American prisoners of war were also subjected to experiments designed to infect the victims with fatal diseases including: plague, cholera, tuberculosis, typhoid, tetanus, anthrax, typhus, hemorrhagic fever, and dysentery. See, list “medically usable specimens” (i.e., pathogens) compiled in a U.S. occupation report . The victims were then vivisected — many while still alive. Live vivisection was a Japanese “specialty.”

The experiments conducted at Unit 731 and its satellites can be classified into the following broad categories: Vivisections for training new Army surgeons: These were performed at army hospitals in China using many Chinese prisoners. The doctors were trained to perform appendectomies and tracheotomies; prisoners were shot, then doctors removed the bullets from their bodies; they amputated their arms and legs and sewed up the skin around the wounds, and finally killed the prisoners. This surgical training program was to teach newly minted army surgeons how to treat wounded soldiers at the front lines. However, unlike normal medical training which teaches surgical skills while avoiding causing harm to patients, the training of these army doctors encourages causing needless harm and death. So, it has been suggested that training under Unit 731 supervision, was not required at all, but rather its main purpose was to desensitize the surgeons, rather than to perfect their surgical skills. (Takashi Tsuchiya.  Why Japanese doctors performed human experiments in China 1933-1945 ,  Eubios Journal of Asian and International Bioethics, 2000)

Intentional infecting with viruses and pathogens followed by vivisection either after death or vivisected to death. Doctors purposefully infected victims with diseases ;  victims would then be strapped down to an operating table and subjected to live autopsy without anesthesia. Some screamed in a non-human way when they realized their fate. Unit 731 “doctors” would cut them open to observe the progress of the germs incubating within them or to harvest organs that had enough germs to weaponize or spread on nearby villagers. They would amputate limbs to study blood loss and the effects of rotting and gangrene (some limbs were later attached to the other side of the body), parts of the stomach, liver, brains and lungs were often removed to observe the effects. The reason for live vivisection was to study the effect of the pathogens on live human organs and to avoid decomposition.

Germ warfare , male and female prisoners were injected with venereal diseases in the disguise of inoculations (or sometimes infected via rape) to determine the viability of germ warfare, victims were infested with fleas in order to communicate the disease to an organism which could be later dropped onto a populace. During one anthrax operation, the doctors noted the progress of the pathogen organ by organ. The victim’s suffering was unspeakable, with “his organs swelling, bleeding and disintegrating.” Fleas were also tainted with cholera, anthrax, and the bubonic plague, as well as, other plagues. This was the origin of the “flea bomb” which infected large geographic areas and polluted land and water. They were dropped in the guise of clothing and supplies which resulted in the estimated death of another 400,000–580,000 Chinese civilians. (Read more: China History Forum , 2005.)

Weapons testing,  grenades, mortars and other explosive devices were detonated near living targets to determine the effects with regards to different distances and angles, so they could determine how long victims could survive with their sustained injuries; experiments to determine the ability of the human body to survive in the face of various pathogens and in conditions such as extreme cold; Chinese prisoners were exposed to mustard gas in a simulated battle situation; others were tied to stakes tests to determine the lethality of biological, and chemical weapons and other explosive material.

Physical endurance experiments,  to determine the physical tolerance level of human beings. The experiments were designed to answer questions such as: how much air could be injected intravenously; how much poison gas could be inhaled; how much bleeding caused death; how many days prisoners could survive without food or water; how high electric current human beings could bear; air pressurized, oxygen deprivation experiments — same as those conducted in Nazi concentration camps; frostbite experiments where prisoners would lose entire limbs and suffer gangrene; forced sex between prisoners (most often one that was infected with a STD while the other was healthy). In other experiments victims were hung upside down to observe how long it took for one to die due to choking and the length of time until the onset of embolism occurred after inserting air into ones blood stream. Read more: Unit 731

Nonstardized treatment tests and Sadistic what if? Experiments . Numerous experimental vaccines were tested on prisoners with no animal trials; Victims were hung upside down to observe how long it took for one to die due to choking; the length of time until the onset of embolism occurred after inserting air into ones blood stream; what would happen if horse serum got injected into the body of a human?

“Other experiments were conducted so the doctors could learn more about how humans live and die. These included studies of dehydration, starvation, frostbite, air pressure – some inmates had their eyes blown out – transfusions of animal blood to humans and others. Even children and babies were destroyed this way. Other ghoulish experiments included cutting off a prisoner’s hands and sewing them back on to the opposite arms to gauge what happened.” ( China History Forum , 2005)

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Unit 731: Imperial Japan’s Biological and Chemical Warfare

Written by Romeo Jung.

Introduction

Unit 731 was a secret Biological and Chemical Warfare Unit that Imperial Japan had established during the World War II. Eager to win the war, the scientists involved committed a lot of inhumane crimes like vivisection to Chinese, Korean, Russian, and Mongolian prisoners of war, and used the data gained to harm many Chinese civilians. This essay details heavily on the biological research and its data from start to the end as well as their impacts and aftermath.

Unit 731 was established first in 1932 as a small group of five scientists interested in biological weapons, and was expanded around 1936 when Shiro Ishii was given full command of the unit. Given alternative names like “lumber yard” and “Epidemic Prevention and Water Purification Department of the Kwantung Army”, the name “Unit 731” was made formal in 1941.  The lab was based at the Epidemic Prevention Research Laboratory in Japanese Army Military Medical School in Tokyo. Their purpose was none of the given names, but biological and chemical warfare research.

The idea of Unit 731 first circulated around by a memo written in April 23, 1936, that speaks about the establishment of reinforcement military forces in Manchuria. The memo states that there would be a new “Kwantung Army Epidemic Prevention Department” and that it shall be expanded later on. 

The headquarters was set in three square kilometers of land in Pingfang district, Manchuria. Many of the lab’s buildings inside were hidden by a tall wall and high voltage wired fences. The lab had around 150 buildings, including incinerator, housing for prisoners, an animal house, and air field. The buildings were completely isolated from the outside world, with only a tunnel as the entrance.

Unit 731, along with two other units to be mentioned later, was created in opposition to the Geneva protocol of 1925 banning biological and chemical warfare. This protocol was signed at June 17, 1925 in Geneva. It became effective from February 8th, 1928, and got registered by League of Nations Treaty Series on September 7, 1929.

Within Unit 731, there were eight subunits designed to focus on different topics of warfare. The first division focused on biological weapons like bubonic plague, cholera, anthrax, typhoid, and tuberculosis, with human subjects to work with. The second division  focused on effectively spreading the biological weapons covered in the first division. The third division was focused on a specific way of spreading biological agents by bomb, the fourth on bacteria mass production and storage. The fifth through eighth divisions  were mostly focused on the supplying the rest of the Unit, which included training workers, providing equipment, and overall administrative units.

Outside of Unit 731, Japan established two departments: Unit 100 and Unit 516. Unit 100 was first declared as the “Kwantung Army Military Horse Epidemic Prevention Workshop,” which focused on developing biological weapons aside from Unit 731. “Kwantung Army Technical Testing Department”, later called Unit 516, was also established for more research that focused on chemical weapons. 

People Involved

There were many involved with the research of Unit 731, most of them remaining anonymous to this day. Shiro Ishii was the Chief of Unit 731, with Masaji Kitano as second in command. Other scientists were most likely to be a Professor at an university or a chief of a medical research unit, like Dr. Hisato Yoshimura, who directed the frostbite experiments on subjects, and Dr. Hideo Futaki, who lead the tuberculosis research squad and some vivisections. Other personnels include Lieutenant Shunichi Suzuki, who, after the trials, went to work as the Governor of Tokyo, and Amitani Shogo, who remained at the lab afterwards and received the Asahi Prize for outstanding scientific performance.

Shiro Ishii served in the Imperial Japanese Army from 1921 to 1945, and in the meantime, he was a Japanese army medical officer, microbiologist, and the director of Unit 731. Before serving in the army, he had studied medicine at Kyoto Imperial University. He was first assigned as an army surgeon, then to the First Army Hospital and Army Medical School in Tokyo. His work soon impressed the superiors, which earned him postgraduate level medical education. Ishii was promoted to an army surgeon in 1925, and was advocating for a biological weapons research program.

After getting promoted to higher ranks, Ishii began his experiments in Zhongma Fortress for biological weapons. Then the government granted him permission to set up Unit 731 in his hopes of digging deeper into the topic. After World War II, he was arrested for a short time by the US occupation authorities for Unit 731, then received immunity from consequences in exchange for data. There are different accounts as to what he did after that, but some say that he traveled around to give talks about biological weapons and others say that he stayed in Japan to provide medical services for free.

What They Did

In Unit 731, the first division conducted many outrageous experiments which were violating human rights. They conducted   many experiments that tested the limitations of the human body. The prisoners, used as subjects, were of mixed ethnicity and gender, some pregnant, and some as young as three years old.  The prisoners, tied to stakes, would have to endure the biological agent bombs that carried plague infested fleas on them or rats with the diseases. Then they were subject to their body being cut open with a scalpel and examined while they were screaming for mercy on the table. 

An unnamed Unit 731 surgeon, in an interview with  New York Times, described his experience with the unit. His first vivisection, which he recalled that he “cut [the prisoner] open from the chest to the stomach, and he screamed terribly, and his face was all twisted in agony… …finally he stopped. This was all in a day’s work for the surgeons…” (Kristof) There was no use of anesthetics during vivisections at all because they were afraid that it would have an effect on the results and data.

In another part of his article, Kristof interviews a former medical worker in Unit 731, Takeo Wano. Wano says that he had seen “six-foot-high glass jar in which a Western man was pickled in formaldehyde. The man had been cut into two pieces, vertically.” There were many other jars in the headquarters of Unit 731 containing other body parts from different people, labeled often as their ethnicity. An anonymous Unit 731 veteran says that most of the jars had been noted as Chinese, Korean, and Mongolian, although there were occasionally American, English, and French. Some body parts were even sent in from other places.

Other experiments included prisoners being locked inside a pressure chamber to test how much pressure the body can handle before their eyes started popping out, being exposed to poisonous gas and many more biological and chemical weapons, having limbs cut off for studying blood loss, having cut off limbs attached to different parts of the body, having horse urine injected into kidneys, and having lethal dosages of x-rays. Kristof noted that “The accounts are wrenching to read even after so much time has passed: a Russian mother and daughter left in a gas chamber, for example, as doctors peered through thick glass and timed their convulsions, watching as the woman sprawled over her child in a futile effort to save her from the gas.”

Hisato Yoshimura, apart from infection based experiments, led the frostbite experiments, which focused on the effects of frostbite on human limbs. He gave orders to freeze limbs of prisoners, often until they were black. The prisoners were let in only when an officer was sure that their limbs were frozen. The officers would test limbs by beating them with a stick, as they knew that frozen limbs sound like wooden boards upon hitting. 

After chilling prisoners’ limbs to near 0 degrees Celsius with ice water, Yoshimura continued to chop off parts of the limb, especially fingers, so that he may record how the frostbite was affecting human limbs. He and his team experimented on subjects as young as three years old, with a needle in their finger to keep it from clenching into a fist. 

Effects During War

The Japanese Military used the biological weapons developed by Unit 731 directly on Chinese civilian population. Agents in divisions other than the first division in Unit 731 would spread the diseases by train, road, and airplanes. Many Chinese civilians developed the worst infections on their limbs, and only a few were exposed to treatment since no local doctors or hospitals had seen the infections before.

Quzhou village, Ya Fan village, and Chong Shan village in the Zhejiang Province had suffered deeply from the Bubonic Plague, as well as Dysentery, Typhoid, Cholera, and many more. In an episode of BBC Correspondent,  Wu Shi-Gen, a victim of Unit 731’s biological weapons, tells his story of how the Bubonic Plague had affected his nine-year old brother. The rest of the family chose to lock his little brother away in another room to minimize the possibilities of infections while the little boy cried out from the room. Wu said he still remembers how he could not run in and help his brother when he cried out in pain.

Ya Fan village was affected with an unknown infection, commonly known to residents as “The Rotten Leg Disease.” A victim of this infection describes it as something that “started like an insect bite, then swelling and unbearable pain. Then his flesh started rotting away. Many died of it. Experts say it’s probably Glanders, another of Unit 731’s special recipes. Treatments were ineffectual and cost a fortune.” He stated that while his mother and he both had the disease on their legs, she refused the medicine so that he could have it instead of her. She passed away a few months later.

Aside from negative effects, Unit 731’s research was also used to heal Japanese soldiers with certain conditions. Studying about human conditions like frostbites and different diseases, the doctors could effectively pinpoint medical solutions for their sick soldiers. For instance, the frostbite experiment revealed that putting frozen limbs in water from 100 to 122 degrees Celsius is the best.

As soon as the World War II was over, the scientists at Unit 731’s headquarters started burning the building down, getting rid of all the evidence. When Shiro Ishii and many others were captured by China and sent over to the US for a trial, they had a deal with President MacArthur. He decided to let go of the Unit 731’s scientists free of charge for the war crimes in exchange for their medical research data.

In addition, Japanese government was fairly late to apologize to the rightful victims of Unit 731, while paying war tributes to the dead war criminals of Unit 731. They have been continuously visiting their shrines every year since 2013, offending neighboring countries and victims. Many news articles had been written about it, yet they do not seem to matter to the Japanese government.

Many Japanese scholars also deny the fact that there was ever a Unit 731 and state that the history involving the group is fabricated, although there are plenty of evidences. The Japanese history textbooks do not cover most of Japan’s horrific acts in World War II, leading them to believe that Japan was mostly a victim country rather than hostile like their opponents. By large, the Japanese public has a false sense of history due to the fact that their history textbooks are skewed. 

The former members of Unit 731 seem to have conflicting opinions about the publicity of the topic. Yoshio Shinozuka and some others had gone to give talks and share information about Unit 731, but others like Toshimi Mizobuchi intend to keep the promise to hide the information. A portion of Unit 731 members still hold their annual staff reunion parties hosted by Mizobuchi.

Unit 731 has been one of of the most cruel groups to do human experimentation, yet so few people that I’ve met know about what really happened. Although these inhumane experiments could be defended by saying that they were useful for modern medical science, they were definitely not worth the cost of many civilian lives as well as prisoners’ suffering.

Maruta — “Log” in Japanese. Prisoners were often called logs so that they could be experimented on without scientists feeling remorse.

Vivisection —  Much like dissection, but with an alive person.

Unit 731: Japan’s Biological Warfare Project. (2018). Retrieved March 14, 2018, from https://unit731.org/ Kristof, N. D. (1995, March 17). Unmasking Horror — A special report.; Japan Confronting Gruesome War Atrocity. Retrieved March 24, 2018, from https://www.nytimes.com/1995/03/17/world/unmasking-horror-a-special-report-japan-confronting-gruesome-war-atrocity.html?pagewanted=all L. (2013, February 11). Unit 731: Japan’s biological force. Retrieved March 24, 2018, from https://www.youtube.com/watch?v=8LfMNX3TsT0 Working, R. (2001, June 5). The trial of Unit 731. Retrieved March 24, 2018, from https://www.japantimes.co.jp/opinion/2001/06/05/commentary/world-commentary/the-trial-of-unit-731/#.WqoQ6z9zJhE McCurry, J. (2013, December 26). Japan’s Shinzo Abe angers neighbours and US by visiting war dead shrine. Retrieved March 24, 2018, from https://www.theguardian.com/world/2013/dec/26/japan-shinzo-abe-tension-neighbours-shrine Beijing, S. A. (2014, October 17). China protests at Japanese PM’s latest WW2 shrine tribute. Retrieved March 24, 2018, from https://www.theguardian.com/world/2014/oct/17/china-protests-japan-shinzo-abe-yasukuni-shrine Japanese PM Abe sends ritual offering to Yasukuni shrine for war dead. (2017, October 17). Retrieved March 24, 2018, from https://www.reuters.com/article/us-japan-yasukuni/japanese-pm-abe-sends-ritual-offering-to-yasukuni-shrine-for-war-dead-idUSKBN1CL355 Abe training jet photo sparks outrage in South Korean media. (2013, May 15). Retrieved March 24, 2018, from http://www.scmp.com/news/asia/article/1238533/abe-training-jet-photo-sparks-outrage-south-korean-media Tsuneishi, K. (2005, November 24). Unit 731 and the Japanese Imperial Army’s Biological Warfare Program. Retrieved March 24, 2018, from https://apjjf.org/-Tsuneishi-Keiichi/2194/article.html Pure Evil: Wartime Japanese Doctor Had No Regard for Human Suffering. (2016, June 15). Retrieved March 24, 2018, from https://www.medicalbag.com/despicable-doctors/pure-evil-wartime-japanese-doctor-had-no-regard-for-human-suffering/article/472462/ Tsuchiya, T. (2007, December 16). Retrieved March 24, 2018, from http://www.lit.osaka-cu.ac.jp/user/tsuchiya/gyoseki/presentation/UNESCOkumamoto07.html Unit 731: One of the Most Terrifying Secrets of the 20th Century. (n.d.). Retrieved March 26, 2018, from https://www.mtholyoke.edu/~kann20c/classweb/dw2/page1.html

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Shiro ishii and the dark legacy of japan’s unit 731.

• War Articles
• World War 2

Japanese physician Shiro Ishii presided over a series of abhorrent medical experiments that stand as some of the most egregious atrocities in modern history. Ranging from the development and testing of biological warfare agents to conducting live dissections on victims, the actions of Unit 731 constituted unspeakable crimes against humanity, targeting men, women and children in ways that defy comprehension, even by contemporary standards.

Shiro Ishii’s early life

Shiro Ishii’s background was one of prominence in feudal Japan, with his family being the largest landowners in their community. One of four siblings, his father earned a living as a local sake maker. Noted for his assertive demeanor, Ishii was characterized by his peers as “brash, abrasive, and arrogant” from a young age.

Following the completion of his medical studies at Kyoto Imperial University in 1920, Ishii embarked on a career in the Imperial Japanese Army (IJA) as a military surgeon. His exceptional performance garnered the admiration of his superiors, leading to an invitation to return to Kyoto Imperial University for post-graduate research in 1924.

Preferring bacterial cultures over human interaction

During this period, accounts from those who collaborated with Shiro Ishii paint a picture of his demeanor, characterized by what some described as “pushy behavior” and “indifference” toward his peers. Instead of forming connections with fellow his humans, Ishii’s affections were directed toward the bacterial cultures he cultivated in Petri dishes, which he treated as companions.

Known for his habit of lingering in laboratories well past regular hours, Ishii would use equipment painstakingly cleaned by students, intentionally leaving behind soiled instruments with the expectation that others would be punished. This odd and detached behavior foreshadowed Ishii’s later treatment of human subjects as mere objects.

Shiro Ishii wanted Japan to create a biological weapons program

By 1927, Shiro Ishii began promoting his aspirations to establish a Japanese biological weapons program, despite Japan having ratified the Geneva Protocol two years earlier, which prohibited the use of biological and chemical warfare. In early 1931, his dedication and loyalty to Emperor Hirohito, coupled with his frequent late-night endeavors in the laboratory, culminated in his promotion to Senior Army Surgeon, Third Class.

Around the time of Ishii’s promotion, China and Japan found themselves locked in a tense conflict. With the latter’s annexation of Chinese territories , an opportunity arose to establish testing facilities and capitalize on the ample number of Chinese prisoners to conduct abhorrent experiments on.

Ishii’s initial testing site was a facility known as Zhongma Fortress , in Beiyinhe, China. Approximately 1,000 prisoners were held within and subjected to harrowing tests, such as rigorous blood extraction sessions recurring every three to five days, relentlessly sapping their strength until they were rendered incapable to go on.

The facility ceased operations in 1936. However, by then, Ishii had set his sights on the establishment of a facility designed for even more depraved experiments.

Establishment of Unit 731

Promoted to the rank of Senior Army Surgeon, Second Class, Shiro Ishii assumed command of what became the infamous Unit 731 in 1936.

Operating under the guise of the Epidemic Prevention and Water Purification Department of the Kwantung Army, Unit 731 was a clandestine entity dedicated to chemical warfare research and development. However, the façade of its bureaucratic label belied its true nature. Unit 731 was a vehicle for the systematic torture and murder of countless innocents under the pretext of scientific advancement and national progress.

Under Ishii’s leadership, Unit 731 began a macabre initiative known as Maruta , wherein human beings were ruthlessly subjected to experimentation. The term originates from the Japanese word for “logs,” a grim reference to the callous manner in which test subjects were derisively labeled by their tormentors.

Officially cloaked as lumber mills, Unit 731 facilities operated under the guise of mundane industrial endeavors. To maintain the veil of secrecy surrounding their heinous activities, researchers and guards would casually refer to prisoners and victims as “logs,” employing coded language such as “How many logs fell today?” to obscure the true nature of their work.

Prisoners were subjected to horrific experimentation

Prisoners endured a litany of barbaric experiments under Unit 731.

They were systematically injected with virulent diseases, subjected to excruciating vivisections without anesthesia and compelled to endure a spectrum of torturous medical experiments. Procedures ranged from limb amputations aimed at studying blood loss to confinement in overheated chambers equipped with fans. Women were routinely subjected to assault, their bodies exploited to provide infants for further experimentation.

Many of these experiments were orchestrated to replicate battlefield conditions, serving as macabre simulations to enhance military medical knowledge and treatment protocols for combat-related injuries. Some prisoners were subjected to chilling conditions, forced to endure prolonged exposure to cold temperatures with their hands submerged in water. These aimed to provide insights into the treatment of frostbite injuries.

Meanwhile, others were subjected to the relentless forces of centrifuges, enduring intense pressure until the point where the sheer force caused their eyes to protrude from their sockets. These harrowing tests were conducted in an attempt to ascertain the limits of bodily endurance under extreme pressure.

Shiro Ishii had an obsession with the plague-bomb

A significant portion of Unit 731’s research was dedicated to Operation Cherry Blossoms at Night , an initiative orchestrated by Shiro Ishii that aimed at disseminating plague-infected rats across Allied-occupied territories during World War II . While the plan never came to fruition, the purported “research” phase of the project exacted a devastating toll on countless lives.

At least 12 large-scale field trials were conducted across 11 Chinese cities. One particular attack in 1941 resulted in the deaths of 10,000 locals and an additional 1,700 Japanese troops from cholera. Pathogens such as smallpox, anthrax, botulism and bubonic plague were weaponized and deployed in defoliation bacilli bombs or flea bombs, targeting densely populated areas.

Following the release of these plague-bombs, researchers, dressed in hazmat suits, monitored the effects on unsuspecting victims. By 1945, the Japanese had advanced preparations for the implementation of Operation Cherry Blossoms at Night, with plans to unleash thousands of plague-infested rats along California’s coast on September 22 of that year. However, the surrender of Japan occurred five weeks prior to the scheduled date.

Shiro Ishii was arrested for his war crimes

Shiro Ishii was arrested by the United States during the post-war Occupation of Japan . However, justice remained elusive. He and his associates negotiated a deal granting them immunity in return for divulging their insights into the Japanese military and their research endeavors.

Japanese medical authorities, when interviewed by American officials, adamantly portrayed themselves as mere microbiologists. An interviewer of Ishii’s associates attested to the “absolutely invaluable” nature of the information they supplied.

Following the 1948 immunity agreement, Ishii evaded prosecution for his war crimes and retreated from the public eye. Rumors regarding his whereabouts varied, with some suggesting he moved to Maryland, while others claimed he continued to reside in Japan, possibly practicing medicine.

More from us: USS Missouri (BB-63): American Battleship and the Site of the Japanese Surrender

Ishii passed away on October 9, 1959, succumbing to throat cancer in Shinjuku, Tokyo.

Unit 731 , short for Manshu Detachment 731 , was a unit of the Imperial Japanese Army that engaged in unethical and deadly human experimentation , including testing of biological and chemical weapons on human populations, during the Second Sino-Japanese War (1937–1945) and World War II . Based in Japanese-occupied China , it was responsible for some of the most notorious war crimes committed by the armed forces of Imperial Japan, including anthrax, cholera , and bubonic plague attacks on both military and civilian populations; vivisection of men, women, children, and infants (often without anesthesia); testing of grenades and flamethrowers on people; and subjecting victims to water deprivation, low pressure, low temperature (causing frostbite), chemical agents, amputation and limb reattachment, being buried alive, and other atrocities. Because Shirō Ishii was director of Unit 731, the division has also been referred to as the Ishii Unit.

• 2.1 Zhongma Fortress
• 2.2 Unit 731
• 2.3 Other units
• 3.1 Chemical agents and chemical weapons
• 3.2 Biological agents and biological weapons
• 3.3 Frostbite testing
• 3.4 Vivisection
• 3.5 Venereal diseases
• 3.6 Weapon testing
• 3.7 Other experiments
• 4 Victims, including numbers of victims
• 5 Known unit members
• 6 Divisions
• 7 Facilities
• 8.1 Destruction of evidence and arrest
• 8.2 American grant of immunity
• 8.3 Separate Soviet trials
• 8.4 Aftermath
• 10 References

The heinous acts of torture committed by Unit 731 mirrored the inhumane experimentation conducted on prisoners by Nazi Germany. However, the aftermath of the two atrocities were very different. Many of the perpetrators of the Nazi human experimentation were tried by the United States in the Doctors' Trial , and the response to the unveiling of the Nazi crimes included the pivotal development of the Nuremberg Code and subsequently other sets of ethical standards for research with human subjects. In the case of Unit 731, most of the key participants in Unit 731, including Shirō Ishii, escaped prosecution via an agreement with the United States to provide their research findings. In addition, most of the Unit 731 crimes escaped public attention for years. Some of those responsible for Unit 731 were captured by the Soviet Union and subject to trials by that nation.

Unit 731 was active in Japanese-occupied territory in Asia, notably Manchuria . The Empire of Japan first invaded Manchuria in 1931, and in 1932 established the puppet state of Manchukuo. The formation of Unit 731 began in 1932 with the establishment of a research group in Manchukuo for chemical and biological experimentation.

Japan occupied other areas in Asia during the Second Sino-Japanese War and the Second World War and established branch offices of Unit 731 in some of these areas as well. The Second Sino-Japanese War (1937–1945) was primarily waged between the Republic of China (1912–1949) and the Empire of Japan. The beginning of the war is conventionally dated to the Marco Polo Bridge Incident on July 7, 1937, when a dispute between Japanese and Chinese troops in Beijing escalated into a full-scale invasion. This full-scale war between the Chinese and the Empire of Japan is often regarded as the beginning of World War II in Asia: after the Japanese invasion of Malaya and attack on Pearl Harbor in 1941, the Second Sino-Japanese War merged with other conflicts that are generally categorized under those conflicts of World War II. However, some scholars consider the European theatre of World War II and the Pacific War to be entirely separate, albeit concurrent, wars. Other scholars consider the start of the full-scale Second Sino-Japanese War in 1937 to have been the beginning of World War II. Following the Marco Polo Bridge Incident, the Japanese scored major victories, capturing Beijing, Shanghai, and the Chinese capital of Nanjing in 1937. After failing to stop the Japanese in the Battle of Wuhan, the Chinese central government was relocated to Chongqing (Chungking) in the Chinese interior.

The formation of Unit 731 traces to 1932, when Surgeon General Shirō Ishii, chief medical officer of the Imperial Japanese Army, organized a secret research group, the "Tōgō Unit," for chemical and biological experimentation in Manchuria. In 1936, Emperor Hirohito authorized the expansion of this unit and its integration into the Kwantung Army as the Epidemic Prevention Department (Barenblatt 2005). In 1940, it became known as the Epidemic Prevention and Water Purification Department of the Kwantung Army (Tanaka 1996), or Unit 731 ( 731部隊 , Nana-san-ichi Butai ) , short for Manshu Detachment 731. It is also known as the Kamo Detachment (USSR 1950) and the Ishii Detachment or Ishii Unit (CIA 1947). Unit 731 was based in the Pingfang district of Harbin, the largest city in the Japanese puppet state of Manchukuo, but also had active branch offices throughout China and Southeast Asia. (Note that the Japanese word butai is variously translated with military terms such as "unit," "detachment," "regiment," or "company.")

Unit 731 was commanded until the end of World War II by General Ishii. The facility itself was built in 1935 as a replacement for the Zhongma Fortress, and Ishii and his team used it to expand their capabilities. The program received generous support from the Japanese government until the end of the war in 1945. Unit 731 and the other units of the Epidemic Prevention and Water Purification Department operated biological weapon production, testing, deployment and storage facilities. They routinely conducted tests on human beings (who were internally referred to as "logs"). Additionally, the biological weapons were tested in the field on cities and towns in China. Estimates of those who were killed by Unit 731 and its related programs range up to half a million people.

The researchers in Unit 731 were secretly given immunity by the United States in exchange for the data which they gathered during their human experimentation (Gold 1996). Other researchers that the Soviet forces managed to arrest first were tried at the Khabarovsk War Crime Trials in 1949. The Americans did not try the researchers so that the information and experience gained in bio-weapons could be co-opted into their biological warfare program, much as they had done with Nazi researchers in Operation Paperclip (Harris 2002). Victim accounts were then largely ignored or dismissed in the West as communist propaganda (Brody et al. 2014).

In 1932, Surgeon General Shirō Ishii ( 石井四郎 , Ishii Shirō ) , chief medical officer of the Imperial Japanese Army and protégé of Ministry of War of Japan Sadao Araki was placed in command of the Army Epidemic Prevention Research Laboratory (AEPRL). Ishii organized a secret research group, the "Tōgō Unit," for chemical and biological experimentation in Manchuria. Ishii had proposed the creation of a Japanese biological and chemical research unit in 1930, after a two-year study trip abroad, on the grounds that Western powers were developing their own programs.

One of Ishii's main supporters inside the army was Colonel Chikahiko Koizumi, who later became Japan's Health Minister (Minister of Health, Labor, and Welfare) from 1941 to 1945. Koizumi had joined a secret poison gas research committee in 1915, during World War I , when he and other Imperial Japanese Army officers were impressed by the successful German use of chlorine gas at the Second Battle of Ypres, in which the Allies suffered 5,000 deaths and 15,000 wounded as a result of the chemical attack (Williams and Wallace 1989).

Zhongma Fortress

Unit Tōgō was implemented in the Zhongma Fortress, a prison/experimentation camp in Beiyinhe, a village 100 km (62 mi) south of Harbin on the South Manchuria Railway. Prisoners were generally well fed on the usual diet of rice or wheat , meat , fish, and occasionally even alcohol, with the intent of having prisoners in their normal state of health at the beginning of experiments. Over several days, prisoners were eventually drained of blood and deprived of nutrients and water. Their deteriorating health was recorded. Some were also vivisected. Others were deliberately infected with plague bacteria and other microbes.

In the autumn of 1934, a prison break, which jeopardized the facility's secrecy along with a later explosion (believed to be sabotage) in 1935 led Ishii to shut down Zhongma Fortress. He then received authorization to move to Pingfang, approximately 24 km (15 mi) south of Harbin, to set up a new, much larger facility (Harris 2002).

In 1936, Emperor Hirohito authorized by decree the expansion of this unit and its integration into the Kwantung Army as the Epidemic Prevention Department (Barenblat 2005). It was divided at that time into the "Ishii Unit" and "Wakamatsu Unit," with a base in Hsinking (Changchun; it was renamed Hsinking during the Japanese occupation, serving as the capital of Imperial Japanese puppet state of Manchukuo). From August 1940, the units were known collectively as the "Epidemic Prevention and Water Purification Department of the Kwantung Army (関東軍防疫給水部本部)" (Tanaka 1996) or "Unit 731" (満州第731部隊) for short.

Other units

In addition to the establishment of Unit 731, the decree also called for the establishment of an additional biological warfare development unit called the Kwantung Army Military Horse Epidemic Prevention Workshop (later referred to as Manchuria Unit 100) and a chemical warfare development unit called the Kwantung Army Technical Testing Department (later referred to as Manchuria Unit 516). After the Japanese invasion of China in 1937, sister chemical and biological warfare units were founded in major Chinese cities and were referred to as Epidemic Prevention and Water Supply Units. Detachments included Unit 1855 in Beijing, Unit 1644 in Nanjing, Unit 8604 in Guangzhou, and later Unit 9420 in Singapore. All of these units comprised Ishii's network and at its height in 1939 was composed of more than 10,000 personnel (Keiichi 2005). Medical doctors and professors from Japan were attracted to join Unit 731 by the rare opportunity to conduct human experimentation and strong financial support from the Army (NHK 2017).

Human experiments

Human experimentation was conducted using men, women, and children — including infants, the elderly, and pregnant women — both inside the facility and among surrounding populations. The subjects included common criminals, captured bandits, anti-Japanese partisans, political prisoners, the homeless and mentally handicapped, and also people rounded up by the Kempeitai military police for alleged "suspicious activities." Ordinary citizens were also subjects to the tortures and death conducted by the researchers. The members of Unit 731 included approximately 300 researchers, including doctors and bacteriologists (Harris 2002). Many of the researchers had been desensitized to performing cruel experiments from experience in animal research (Cook and Cook 2000).

Test subjects were sometimes euphemistically referred to as "logs" ( 丸太 , maruta ) , used in such contexts as "How many logs fell?" This term may have originated by Unit 731 staff based on the fact that the official cover story for the facility was that it was a lumber mill. However, in an account by a man who worked as a junior uniformed civilian employee of the Imperial Japanese Army in Unit 731, the project was internally called "Holzklotz," which is a German word for log (Cook and Cook 2000). Researchers in Unit 731 published some of their results in peer-reviewed journals, writing as though the research had been conducted on non-human primates called "Manchurian monkeys," or "long-tailed monkeys" (Harris 2002).

Experiments conducted on subjects included those involving chemical agents and chemical weapons, biological agents and biological weapons, frostbite, vivisection, venereal diseases, and weapons testing, among others.

Chemical agents and chemical weapons

Unit 731 tested many different chemical agents on prisoners and had a building dedicated to gas experiments. Some of the agents tested were mustard gas, lewisite, cyanic acid gas, white phosphorus, adamsite, and phosgene gas (Gold and Totani 2019).

A former army major and technician gave the following testimony anonymously (at the time of the interview, this man was a professor emeritus at a national university) (Gold and Totani 2019):

In 1943, I attended a poison gas test held at the Unit 731 test facilities. A glass-walled chamber about three meters square and two meters high was used. Inside of it, a Chinese man was blindfolded, with his hands tied around a post behind him. The gas was adamsite (sneezing gas), and as the gas filled the chamber the man went into violent coughing convulsions and began to suffer excruciating pain. More than ten doctors and technicians were present. After I had watched for about ten minutes, I could not stand it any more, and left the area. I understand that other types of gases were also tested there.

Unit 731 also tested chemical weapons on prisoners in field conditions. A report authored by an unknown researcher in the Kamo Unit (Unit 731) describes a large human experiment of yperite gas (mustard gas) on September 7—10, 1940. Twenty subjects were divided into three groups and placed in combat emplacements, trenches, gazebos, and observatories. One group was clothed with Chinese underwear, no hat, and no mask, and was subjected to as much as 1,800 field gun rounds of yperite gas over 25 minutes. Another group was clothed in summer military uniform and shoes; three had masks, and another three had no mask. They also were exposed to as much as 1,800 rounds of yperite gas. A third group was clothed in summer military uniform, three with masks, and two without masks, and were exposed to as much as 4,800 rounds. Then their general symptoms and damage to skin, eye, respiratory organs, and digestive organs were observed at 4 hours, 24 hours, and 2, 3, and 5 days after the shots. Injecting the blister fluid from one subject into another subject and analyses of blood and soil were also performed. Five subjects were forced to drink a solution of yperite and lewisite gas in water, with or without decontamination. The report describes conditions of every subject precisely without mentioning what happened to them in the long run (Emanuel et al. 2011).

Biological agents and biological weapons

Unit 731 and its affiliated units were involved in testing of numerous biological agents on humans, including anthrax, typhoid , plague (infectious disease caused by the bacterium Yersinia pestis ), dysentery , tuberculosis , syphilis , tetanus, salmonella , tetrodotoxin (pufferfish or fugu venom), gas gangrene, meningitis, and yellow fever, including the deployment of epidemic-creating biowarfare weapons in assaults against the Chinese populace (both military and civilian) throughout World War II.

At least 12 large-scale field trials of biological weapons were performed, and at least 11 Chinese cities were attacked with biological agents. Plague-infected fleas , bred in the laboratories of Unit 731 and Unit 1644, were spread by low-flying airplanes upon Chinese cities, including coastal Ningbo and Changde, Hunan Province, in 1940 and 1941 (CIA 1947). This military aerial spraying killed tens of thousands of people with bubonic plague epidemics. An expedition to Nanking involved spreading typhoid and paratyphoid germs into the wells, marshes, and houses of the city, as well as infusing them into snacks to be distributed among the locals. Epidemics broke out shortly after, with the conclusion that paratyphoid fever was "the most effective" of the pathogens (Harris 2003; Barenblatt 2004). An attack on Changda in 1941 reportedly led to approximately 10,000 biological casualties and 1,700 deaths among ill-prepared Japanese troops, with most cases due to cholera (Christopher et al. 1997). In addition, poisoned food and candies were given to unsuspecting victims.

During the final months of World War II, Japan planned to use plague as a biological weapon against the United States in Operation Cherry Blossoms at Night. The plan was scheduled to launch on September 22, 1945, but Japan surrendered five weeks earlier (Baumslag 2005; Kristol 1995).

Due to pressure from numerous accounts of the bio-warfare attacks, Chiang Kai-shek sent a delegation of army and foreign medical personnel in November 1941 to document evidence and treat the afflicted. A report on the Japanese use of plague-infested fleas on Changde was made widely available the following year, but was not addressed by the Allied Powers until Franklin D. Roosevelt issued a public warning in 1943 condemning the attacks (Guillemin 2017).

Frostbite testing

Army Engineer Hisato Yoshimura conducted experiments by taking captives outside, dipping various appendages into water of varying temperatures, and allowing the limb to freeze (Tsuchiya 2007). Once frozen, Yoshimura would strike their affected limbs with a short stick, "emitting a sound resembling that which a board gives when it is struck" (Kristof 1995). The affected area was subjected to various treatments. For example, the best temperature for treating frostbite was found to be immersion in water slightly above 100 degrees but less than 122 degrees; this was found to be better than the traditional method of rubbing the affected limb (Kristof 1995).

Members of the Unit referred to Yoshimura as a “scientific devil” and a “cold blooded animal” (LaFleur et al. 2007). Naoji Uezono, a member of Unit 731, described in a 1980s interview a grisly scene where Yoshimura had “two naked men put in an area 40-50 degrees below zero and researchers filmed the whole process until [the subjects] died. The subjects suffered such agony they were digging their nails into each other’s flesh” (Emanuel et al. 2011). Yoshimura’s lack of remorse was evident in an article he wrote for the Journal Of Japanese Physiology in 1950 in which he admitted to using 20 children and a 3-day-old infant in experiments which exposed them to zero-degree-celsius ice and salt water (Yoshimura and Iida 1950). [Kristof (1995) reported about a three-day-old baby had a needle stuck into the middle finger to measure temperature; the needle prevented the hand from clenching into a fist and by keeping the finger straight it made the experiment easier.] Although this article drew criticism, Yoshimura denied any guilt when contacted by a reporter from the Japanese newpaper Mainichi Shinbun (Kei-ichi and Asano 1982).

Yoshimura developed a “resistance index of frostbite” based on the mean temperature 5 to 30 minutes after immersion in freezing water, the temperature of the first rise after immersion, and the time until the temperature first rises after immersion. In a number of separate experiments it was then determined how these parameters depend on the time of day a victim’s body part was immersed in freezing water, the surrounding temperature and humidity during immersion, how the victim had been treated before the immersion (“after keeping awake for a night,” “after hunger for 24 hours,” “after hunger for 48 hours,” “immediately after heavy meal,” “immediately after hot meal,” “immediately after muscular exercise,” “immediately after cold bath,” “immediately after hot bath”), what type of food the victim had been fed over the five days preceding the immersions with regard to dietary nutrient intake (“high protein of animal nature,” “high protein of vegetable nature,” “low protein intake,” and “standard diet”) and salt intake (45 g NaCl per day, 15 g NaCl per day, no salt) (Eckart 2006). This original data are seen in the above figure.

Vivisection

Thousands of men, women, children and infants interned at prisoner of war camps were subjected to vivisection (surgery on a living organism), often without anesthesia and usually ending with the death of the victim (Kristof 1995). Prisoners had limbs amputated in order to study blood loss. Those limbs that were removed were sometimes re-attached to the opposite sides of the body. Some prisoners had their stomachs surgically removed and the esophagus reattached to the intestines. Parts of organs, such as the brain, lungs, and liver, were removed from some prisoners (Parry 2007). Imperial Japanese Army surgeon Ken Yuasa suggests that the practice of vivisection on human subjects was widespread even outside Unit 731 (Kristof 1995), estimating that at least 1,000 Japanese personnel were involved in the practice in mainland China (Hongo 2007).

A former member of the Special Team (who insisted on anonymity) recalled in 1995 his first vivisection conducted at the Unit, involving a 30-year-old man tied to a bed naked, who was dissected without anesthetic (Kristol 1995):

He didn't struggle when they led him into the room and tied him down. But when I picked up the scalpel, that's when he began screaming. I cut him open from the chest to the stomach, and he screamed terribly, and his face was all twisted in agony. He made this unimaginable sound, he was screaming so horribly. But then finally he stopped.

Other sources suggest that it was the usual practice in the Unit for surgeons to stuff a rag (or medical gauze) into the mouth of prisoners before commencing vivisection, in order to stifle any screaming (Yang 2016).

Venereal diseases

To study the effects of untreated venereal diseases, male and female prisoners were deliberately infected with syphilis and gonorrhea , then studied. In some cases, this was done via injection, disguised as vaccinations (Medical Bag 2014).

Unit members also orchestrated forced sex acts between infected and non-infected prisoners to transmit the disease, as the testimony of a prison guard on the subject of devising a method for transmission of syphilis between patients shows (Gold and Tutani 2019):

Infection of venereal disease by injection was abandoned, and the researchers started forcing the prisoners into sexual acts with each other. Four or five unit members, dressed in white laboratory clothing completely covering the body with only eyes and mouth visible, rest covered, handled the tests. A male and female, one infected with syphilis, would be brought together in a cell and forced into sex with each other. It was made clear that anyone resisting would be shot.

After victims were infected, they were vivisected at different stages of infection, so that internal and external organs could be observed as the disease progressed.

Some children infected with syphilis grew up inside the walls of Unit 731. A Youth Corps member deployed to train at Unit 731 recalled viewing a batch of subjects that would undergo syphilis testing: "one was a Chinese woman holding an infant, one was a White Russian woman with a daughter of four or five years of age, and the last was a White Russian woman with a boy of about six or seven" (Gold and Tutani 2019). The children of these women were tested in ways similar to their parents, with specific emphasis on determining how longer infection periods affected the effectiveness of treatments.

Weapon testing

Unit 731 was involved in testing weapons on human subjects, including grenades, flamethrowers, explosives, and other weapons.

Human targets were used to test grenades positioned at various distances and in various positions. Flamethrowers were tested on people (Hickey et al. 2017). Victims were also tied to stakes and used as targets to test pathogen-releasing bombs, chemical weapons, shrapnel bombs with varying amounts of fragments, and explosive bombs as well as bayonets and knives.

To determine the best course of treatment for varying degrees of shrapnel wounds sustained on the field by Japanese soldiers, Chinese prisoners were exposed to direct bomb blasts. They were strapped, unprotected, to wooden planks that were staked into the ground at increasing distances around a bomb that was then detonated. It was surgery for most, autopsies for the rest. —Unit 731, Nightmare in Manchuria (Monchinski 2008; Neuman 2008)

Other experiments

In other tests, subjects were deprived of food and water to determine the length of time until death; placed into low-pressure chambers until their eyes popped from the sockets; experimented upon to determine the relationship between temperature, burns, and human survival; hung upside down until death; crushed with heavy objects; electrocuted; dehydrated with hot fans; placed into centrifuges and spun until death; injected with animal blood; exposed to lethal doses of x-rays ; subjected to various chemical weapons inside gas chambers; injected with sea water; and burned or buried alive (Kristof 1995; Silvester 2006).

Massive amounts of blood were drained from some prisoners in order to study the effects of blood loss according to former Unit 731 vivisectionist Okawa Fukumatsu. In one case, at least half a liter of blood was drawn at two to three-day intervals (Gold and Totani 2019). Unit 731 also performed transfusion experiments with different blood types. Unit member Naeo Ikeda wrote (Eckart 2006):

In my experience, when A type blood 100 cc was transfused to an O type subject, whose pulse was 87 per minute and temperature was 35.4 degrees C, 30 minutes later the temperature rose to 38.6 degrees with slight trepidation. Sixty minutes later the pulse was 106 per minute and the temperature was 39.4 degrees. Two hours later the temperature was 37.7 degrees, and three hours later the subject recovered. When AB type blood 120 cc was transfused to an O type subject, an hour later the subject described malaise and psychroesthesia in both legs. When AB type blood 100 cc was transfused to a B type subject, there seemed to be no side effect.

Female prisoners were forced to become pregnant for use in experiments, with the stated reason the possibility of vertical transmission (from mother to child) of diseases, particularly syphilis. Fetal survival and damage to mother's reproductive organs were objects of interest. Though "a large number of babies were born in captivity," there have been no accounts of any survivors of Unit 731, children included. It is suspected that the children of female prisoners were killed after birth or aborted (Gold and Totani 2019).

While male prisoners were often used in single studies, so that the results of the experimentation on them would not be clouded by other variables, women were sometimes used in sex experiments and as the victims of sex crimes. The testimony of a unit member that served as a guard graphically demonstrated this reality (Gold and Totani 2019):

One of the former researchers I located told me that one day he had a human experiment scheduled, but there was still time to kill. So he and another unit member took the keys to the cells and opened one that housed a Chinese woman. One of the unit members raped her; the other member took the keys and opened another cell. There was a Chinese woman in there who had been used in a frostbite experiment. She had several fingers missing and her bones were black, with gangrene set in. He was about to rape her anyway, then he saw that her sex organ was festering, with pus oozing to the surface. He gave up the idea, left and locked the door, then later went on to his experimental work.

Victims, including numbers of victims

The victims of Unit 731 included prisoners (criminals, anti-Japanese partisans, political dissidents, communist sympathizers, and those arrested for alleged suspicious activities), the homeless and mentally handicapped, and ordinary citizens. The victims included men, women, children, and infants. While the majority were Chinese, the victims also comprised Russians, Mongolians, Koreans, and other populations. There are reports that the victims also consisted of a small number of European, American, Indian, Australian and New Zealander prisoners of war (Wells 2009; Gold and Totani 2019; Harris 2002).

There have been widely varying estimates of the number of people killed due to activities of Unit 731. Sheldon Harris, an American historian, states that over 200,000 were killed in the germ warfare experiments (Harris 2002; Kristoff 1995). He also states that plague-infected animals released near the war's end killed at least 30,000 people in the Harbin area from 1946 through 1948 (Kristoff 1995). During a 2002 international symposium on crimes of bacteriological warfare held in Changde, China (site of a plague flea bombing), there was an estimate given of around 580,000 deaths caused by the germ warfare and human experiments (Barenblatt 2004). On the other hand, Keiichi Tsuneishi, a leading Japanese scholar of Unit 731, is skeptical of such high numbers (Kristoff 1995). At least 3,000 men, women, and children were subjected to experimentation conducted by Unit 731 at the camp based in Pingfang alone, which does not include victims from other medical experimentation sites, such as Unit 100 (Tsuchiya 2006). Note that in addition to Chinese casualties, 1,700 Japanese troops in Zhejiang during the Zhejiang-Jiangxi campaign were killed by their own biological weapons while attempting to unleash the biological agent (Rapoport 2014).

Known unit members

In April 2018, the National Archives of Japan disclosed a nearly complete list of 3,607 members of Unit 731 to Katsuo Nishiyama, a professor at Shiga University of Medical Science. Nishiyama reportedly intends to publish the list online to encourage further study into the unit (McCurry 2018).

Some of the previously disclosed members include:

• Lieutenant General Shirō Ishii
• Lieutenant Colonel Ryoichi Naito, founder of the pharmaceutical company Green Cross
• Professor, Major General Masaji Kitano, commander, 1942–1945 (Christopher et al. 1997; Fuller 1992).
• Kazuhisa Kanazawa, chief of the 1st Division of Branch 673 of Unit 731
• Ryoichiro Hotta, member of the Hailar Branch of Unit 731 (Fuller 1992).

There were also twelve members who were formally tried and sentenced in the Khabarovsk War Crime Trials, held in December 1949 in the Soviet Union.

Unit 731 was divided into eight divisions:

• Division 1: research on bubonic plague , cholera , anthrax, typhoid and tuberculosis using live human subjects; for this purpose, a prison was constructed to contain around three to four hundred people
• Division 2: research for biological weapons used in the field, in particular the production of devices to spread germs and parasites
• Division 3: production of shells containing biological agents; stationed in Harbin
• Division 4: bacteria mass-production and storage
• Division 5: training of personnel
• Divisions 6–8: equipment, medical and administrative units

Unit 731 had other units underneath it in the chain of command. Most or all units had branch offices, which were also often referred to as "Units." The term Unit 731 can refer to the Harbin complex itself or it can refer to the organization with its branches.

The Unit 731 complex covered 6 square kilometers (2.3 sq mi) and consisted of more than 150 buildings. The design of the facilities made them hard to destroy by bombing. The complex contained various factories. It had around 4,500 containers to be used to raise fleas , six cauldrons to produce various chemicals, and around 1,800 containers to produce biological agents. Approximately 30 kilograms (66 lb) of bubonic plague bacteria could be produced in a few days.

Unit 731 had branches in Linkou (Branch 162), Mudanjiang, Hailin (Branch 643), Sunwu (Branch 673), Toan and Hailar (Branch 543) (USSR 1950).

A medical school and research facility belonging to Unit 731 operated in the Shinjuku District of Tokyo during World War II. In 2006, Toyo Ishii — a nurse who worked at the school during the war — revealed that she had helped bury bodies and pieces of bodies on the school's grounds shortly after Japan's surrender in 1945. In response, in February 2011 the Ministry of Health began to excavate the site (AP 2011). While Tokyo courts acknowledged in 2002 that Unit 731 had been involved in biological warfare research, the Japanese government had made no official acknowledgment of the atrocities committed against test subjects, and rejected the Chinese government's requests for DNA samples to identify human remains (including skulls and bones) found near an army medical school (The Economist 2011).

Surrender and immunity

Operations and experiments continued until the end of the war. Ishii had wanted to use biological weapons in the Pacific War since May 1944, but his attempts were rejected.

Destruction of evidence and arrest

With the coming of the Red Army in August 1945, the unit had to abandon their work in haste. Ministries in Tokyo ordered the destruction of all incriminating materials, including those in Pingfang. Potential witnesses were killed — the 300 remaining prisoners were either gassed or fed poison and then were cremated; the 600 Chinese and Manchurian laborers were shot. Ishii swore every member of the group to silence and they were told to disappear (Altheide).

Skeleton crews of Ishii's Japanese troops blew up the compound in the final days of the war to destroy evidence of their activities, but many were sturdy enough to remain somewhat intact.

Ishii and various leaders of Unit 731 was arrested by United States authorities during the Occupation of Japan at the end of World War II. They were supposed to be thoroughly interrogated by Soviet authorities (BBC 1984). Instead, Ishii and his team managed to negotiate and receive immunity from prosecution in 1946 from Japanese war-crimes prosecution before the Tokyo tribunal in exchange for their full disclosure (Brody et al. 2014; Kaye 2017).

The Soviet Union did arrest and prosecute twelve top military leaders and scientists from Unit 731 and affiliated units in the Khabarovsk War Crime Trials.

American grant of immunity

Among the individuals in Japan after its 1945 surrender was Lieutenant Colonel Murray Sanders, who arrived in Yokohama via the American ship Sturgess in September 1945. Sanders was a highly regarded microbiologist and a member of America's Military Center for Biological Weapons. Sanders' duty was to investigate Japanese biological warfare activity. At the time of his arrival in Japan he had no knowledge of what Unit 731 was. Until Sanders finally threatened the Japanese with bringing the Soviets into the picture, little information about biological warfare was being shared with the Americans. The Japanese wanted to avoid prosecution under the Soviet legal system, so the next morning after he made his threat, Sanders received a manuscript describing Japan's involvement in biological warfare. Sanders took this information to General Douglas MacArthur, who was the Supreme Commander of the Allied Powers responsible for rebuilding Japan during the Allied occupations. MacArthur struck a deal with Japanese informants: He secretly granted immunity from prosecution to the physicians of Unit 731, including their leader, Ishii, in exchange for providing America, but not the other wartime allies, with their research on biological warfare and data from human experimentation (Gold 2004).

Although the Soviet authorities wished the prosecutions to take place, the United States objected after the reports of the investigating US microbiologists. Among these was Edwin Hill, the Chief of Fort Detrick, whose report stated that the information was "absolutely invaluable;" it "could never have been obtained in the United States because of scruples attached to experiments on humans" and "the information was obtained fairly cheaply" (BBC 1984). On May 6, 1947, Douglas MacArthur wrote to Washington, D.C. , that "additional data, possibly some statements from Ishii probably can be obtained by informing Japanese involved that information will be retained in intelligence channels and will not be employed as 'War Crimes' evidence" (Gold 2004). The reason for the Americans granting immunity was that they believed that the research data was valuable and did not want other nations, particularly the Soviet Union, to acquire data on biological weapons (McNaught 2002).

The Tokyo War Crimes Tribunal heard only one reference to Japanese experiments with "poisonous serums" on Chinese civilians. This took place in August 1946 and was instigated by David Sutton, assistant to the Chinese prosecutor. The Japanese defense counsel argued that the claim was vague and uncorroborated, and it was dismissed by the tribunal president, Sir William Webb, for lack of evidence. The subject was not pursued further by Sutton, who was probably unaware of Unit 731's activities. His reference to it at the trial is believed to have been accidental.

Separate Soviet trials

Although publicly silent on the issue at the Tokyo Trials, the Soviet Union pursued the case and prosecuted twelve top military leaders and scientists from Unit 731, and its affiliated biological-war prisons Unit 1644 in Nanjing and Unit 100 in Changchun, in the Khabarovsk War Crime Trials. Included among those prosecuted for war crimes, including germ warfare, was General Otozō Yamada, the commander-in-chief of the million-man Kwantung Army occupying Manchuria.

The trial of those captured Japanese perpetrators was held in December 1949 in Khabarovsk, Russia, located in southeast Russia, near the border with China. A lengthy partial transcript of the trial proceedings was published in different languages the following year by a Moscow foreign languages press, including an English-language edition (USSR 1950). The lead prosecuting attorney at the Khabarovsk trial was Lev Smirnov, who had been one of the top Soviet prosecutors at the Nuremberg Trials . The Japanese doctors and army commanders who had perpetrated the Unit 731 experiments received sentences from the Khabarovsk court ranging from two to 25 years in a Siberian gulag (labor camp). The United States refused to acknowledge the trials, branding them communist propaganda (Tsuchiya 2011). The sentences doled out to the Japanese perpetrators were unusually lenient by Soviet standards, and all but one of the defendants returned to Japan by the 1950s (with the remaining prisoner committing suicide inside his cell). In addition to the accusations of propaganda, the US also asserted that the trials were only to serve as a distraction from the Soviet treatment of several hundred thousand Japanese prisoners of war; meanwhile, the USSR asserted that the US had given the Japanese diplomatic leniency in exchange for information regarding their human experimentation. The accusations of both the US and the USSR were true, and it is believed that the Japanese had also given information to the Soviets regarding their biological experimentation for judicial leniency (Vanderbrook 2013). This was evidenced by the Soviet Union building a biological weapons facility in Sverdlovsk using documentation captured from Unit 731 in Manchuria (Alibek and Handelman 2000).

There was consensus among US researchers in the postwar period that the human experimentation data gained was of little value to the development of American biological weapons and medicine.

Japanese history textbooks usually contain references to Unit 731, but do not go into detail about allegations (Selden and Nozaki 2009; Masalski 2001). Saburō Ienaga's New History of Japan included a detailed description, based on officers' testimony. The Ministry for Education attempted to remove this passage from his textbook before it was taught in public schools, on the basis that the testimony was insufficient. The Supreme Court of Japan ruled in 1997 that the testimony was indeed sufficient and that requiring it to be removed was an illegal violation of freedom of speech (Asahi Shimbun 1997).

In August 2002, the Tokyo district court ruled for the first time that Japan had engaged in biological warfare. Presiding judge Koji Iwata ruled that Unit 731, on the orders of the Imperial Japanese Army headquarters, used bacteriological weapons on Chinese civilians between 1940 and 1942, spreading diseases including plague and typhoid in the cities of Quzhou, Ningbo, and Changde. However, he rejected the victims' claims for compensation on the grounds that they had already been settled by international peace treaties (Watts 2002).

In October 2003, a member of the House of Representatives of Japan filed an inquiry. Prime Minister Junichiro Koizumi responded that the Japanese government did not then possess any records related to Unit 731, but the government recognized the gravity of the matter and would publicize any records that were located in the future. In April 2018, the National Archives of Japan released the names of 3,607 members of Unit 731, in response to a request by Professor Katsuo Nishiyama of the Shiga University of Medical Science (Japan Times 2018; McCurry 2018).

After WWII, the U.S. Office of Special Investigations created a watchlist of suspected Axis collaborators and persecutors who were banned from entering the United States. While they have added over 60,000 names to the watchlist, they have only been able to identify under 100 Japanese participants. In a 1998 correspondence letter between the DOJ and Rabbi Abraham Cooper, Eli Rosenbaum, director of OSI, stated that this was due to two factors. (1) While most documents captured by the US in Europe were microfilmed before being returned to their respective governments, the Department of Defense decided to not microfilm its vast collection of documents before returning them to the Japanese government. (2) The Japanese government has also failed to grant the OSI meaningful access to these and related records after the war, while European countries, on the other hand, have been largely cooperative (US Dept. of Justice 1998).

• Belmont Report
• Common Rule
• Declaration of Helsinki
• Doctors' Trial
• Human subject research
• Informed consent
• Nazi human experimentation
• Nuremberg Code

References ISBN links support NWE through referral fees

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Unit 731 and the Japanese Imperial Army’s Biological Warfare Program

November 24, 2005

Volume 3 | Issue 11

Article ID 2194

https://apjjf.org/wp-content/uploads/2023/11/article-1720.pdf

By Tsuneishi Keiichi

Translated by John Junkerman

[ Japan’s Unit 731 remains central to the fiercely contested China-Japan controversy over war crimes and war memory, and to the international debate on science and ethics. With a staff of more than 10,000, including many of Japan’s top medical scientists, 731 and its affiliated units conducted human experiments, including vivisection, on Chinese and other victims in Manchukuo and throughout China between 1933 and 1945. The experiments tested, among other things, the lethality of biological weapons and sought to determine the ability of the human body to survive in the face of various pathogens and in conditions such as extreme cold.

Tsuneishi Keiichi is Japan’s leading specialist on biowarfare. His voluminous studies conducted over thirty years in Japan, China, the United States and Europe, have provided core material for all writing hitherto on the Ishii Network. In the following careful resumé essay, he concentrates on organization and function, omitting much of the horrific detail covered elsewhere. Drawing on Japanese military records, this study documents the deaths of 850 victims in the years up to 1943, the largest number infected with plague, cholera, and epidemic hemorrhagic fever. It also makes use of American records and interviews.

Unit 731 not only conducted tests but also led the way in waging biological warfare on numerous occasions throughout the war, the best documented being attacks on Ningbo and throughout Zhejiang province. As in the case of the Nanjing Massacre and the “comfort women,” casualty figures remain contested. The figure of 3,000 persons exterminated at Pingfan, the major experiment site of the Ishii Network, is widely accepted among specialists for the period ending in 1945. The post-surrender destruction by the Japanese authorities both of the research sites and the military documents, has made precise casualty estimates difficult.

As Tsuneishi documents, attacks in Zhejiang resulted in more than 10,000 Japanese military casualties including the death of 1,700 Japanese soldiers, revealing the difficulty of waging effective biowarfare. No estimate is provided here of Chinese deaths. a reminder of contemporary practice in providing only American body counts in Iraq, but also of the difficulty of establishing Chinese casualties.

Japan’s grim experiment with biowarfare pales in comparison with the estimated 10-30 million Chinese who died as a result of war and associated conditions of famine in the years 1931-45. But the findings of Ishii and his colleagues were important enough for American authorities to grant immunity from prosecution in exchange for evidence of the research findings of Unit 731. The 731 scientists, who were evacuated to Japan prior to the defeat, continued their careers as eminent figures in the postwar medical and scientific establishment. ms ]

The Ishii Network

Unit 731 was the common name of a secret unit of Japan’s Manchuria-based Kwantung Army whose official name was the Epidemic Prevention and Water Supply Department. [1] The leader of the unit was Ishii Shiro, who held the rank of lieutenant general at the end of World War II. The unit epitomized the extensive organization for the development of biological weapons within the imperial army, which was referred to, beginning in the late 1930s, as the Ishii Network.

The network itself was based at the Epidemic Prevention Research Laboratory, established in 1932 at the Japanese Army Military Medical School in Tokyo. Unit 731 was the first of several secret, detached units created as extensions of the research lab; the units served as field laboratories and test sites for developing biological weapons, culminating in the experimental use of biological weapons on Chinese cities. The trial use of these weapons on urban populations was a direct violation of the 1925 Geneva Protocol, which outlawed the use of biological and chemical weapons in war. It was also understood by those involved that the use of human subjects in laboratory and test site experiments was inhumane. This was why it was deemed necessary to establish Unit 731 and the other secret units.

The Epidemic Prevention Research Laboratory was created under the initiative of Ishii Shiro after he returned from two years of field study of American and European research facilities. It was set up, with the approval of top-level army authorities, as a facility to develop biological weapons. It is said that Ishii first became convinced of the need to develop biological weapons with the signing of the Geneva Protocol in 1925.

The biological weapons Ishii sought to develop had humans as their target, and Unit 731 was established with this goal in mind. In order to produce biological weapons as quickly as possible, Ishii considered it essential to have a human experimentation site at the disposal of his research laboratory. Japan had occupied northeastern China and in 1932 the puppet state of Manchukuo was established. Within this “safe zone,” Ishii set up what was called the Togo Unit, based in the village of Beiyinhe, about 100 kilometers south of Harbin. Human experimentation began there in the fall of 1933. The Togo Unit was a secret unit under the vice chief of staff of the Kwantung Army. It was set up to determine whether it was possible to conduct human experiments in northeastern China, and if it was possible, whether the experiments would produce useful results. The launching of this feasibility study reflects the deliberate nature of Ishii as the organizer of the research, and you could say it was marked with his character. All of those involved in this research and development were military doctors, but they all used false names. At this stage, the scale of the project involved about ten doctors, along with a staff of about one hundred.

The Inauguration of Unit 731

Unit 731 was officially established in 1936. Its establishment is reflected in a memo dated April 23, 1936, entitled “Opinion Regarding the Reinforcement of Military Forces in Manchuria,” from the chief of staff of the Kwantung Army to the vice minister of the Ministry of War (contained in the Ministry of War Journal for the army in Manchuria, Rikuman Mitsu-dainikki). Under the heading “Establishment and Expansion of the Kwantung Army Epidemic Prevention Department,” the memo states that the department will be “newly established” in 1936 and “one part of the department will be expanded in fiscal 1938.” This is the oldest official document concerning Unit 731 that has been found to date.

In addition to inaugurating Unit 731, this memo also laid the foundation for establishing two other units. It called for the establishment of an additional biological weapons development unit, independent of Ishii’s unit, which was called the Kwantung Army Military Horse Epidemic Prevention Workshop (later referred to as Manchuria Unit 100), and for preparations to set up a chemical weapons development unit called the Kwantung Army Technical Testing Department (later referred to as Manchuria Unit 516).

Several months later, the memo’s recommendations were approved by Emperor Hirohito, the two units were established, and preparations began for creating the Testing Department. The Ministry of War Journal for May 21, 1936 recorded this development under the heading. “Imperial Hearing on Military Force Improvement Consequent upon Budget Approval.” The journal noted: “Units concerned with epidemic prevention: One unit each is established for epidemic prevention among humans and horses.”

Having been officially established, Unit 731 moved its facilities from Beiyinhe to a newly established laboratory at a hospital in Harbin. This laboratory served as a front-line headquarters while the unit’s permanent facilities were being built in Pingfan, outside of the city of Harbin. These facilities were completed and capable of conducting research in the fall of 1939, after the hostilities at Nomonhan (on the border between Manchuria and Mongolia) had ended.

With the construction of the Pingfan facilities, the primary research staff changed in composition from the military doctors of the Togo Unit to private-sector medical researchers affiliated with universities and other institutions. The first group to be posted to the unit was a team of eight assistant professors and instructors from Kyoto Imperial University in the spring of 1938. The group consisted of two bacteriologists, three pathologists, two physiologists, and one researcher specializing in experiments using animals. Within a year, a second group had arrived at the facility, and the research staff had expanded considerably. The prominence of researchers in pathology and physiology in the development of biological weapons reflected the need for specialized judgment in assessing the results of human experimentation.

With the expansion of the war front throughout China after 1937, sister units affiliated with Unit 731 were established in major Chinese cities. These units were also called Epidemic Prevention and Water Supply Departments. (Unit 1855 was established in Beijing on February 9, 1938; Unit 1644 in Nanjing on April 18, 1939; and Unit 8604 in Guangzhou on April 8, 1939). Later, after Japan occupied Singapore a similar unit (Unit 9420) was established there on March 26, 1942. These affiliates comprised the scope of the Ishii network through the end of the war. As of the end of 1939 (that is, before the establishment of the Singapore unit), the network had a total staff of 10,045, of which 4,898 were assigned to the core units in Tokyo and Pingfan.

Human Experimentation

Human experimentation took place at all of the units of the Ishii network, but it was conducted systematically by Unit 731 and Unit 1644. Of these two, there are extant reports from a US Army survey of human experimentation by Unit 731, so the general outline of its program is known.

The following table was compiled from two sources: a report to US occupation authorities dated December 12, 1947 by Edwin Hill and Joseph Victor, concerning human experimentation by Unit 731 and related facilities; and a list of specimens brought back to Japan by a Unit 731 pathologist in July 1943. Aside from Ishii and another unit leader, Kitano Masaji, the names of individual researchers do not appear; they are identified as military personnel (M, primarily military doctors), (C) civilian technicians conducting research within the military, and (PT) part-time researchers working outside of the military.

The number of specimens reflects the number of subjects who died as a result of human experimentation as of July 1943. Consequently, the total number of victims of human experimentation at the time of Japan’s surrender two years later would be higher than these figures. The figures also do not include victims of germ bomb tests at the Anda field test site or from other experiments.

Subject Researcher Total Specimens Medically Usable Specimens anthrax M 36 31 botulinus Ishii 2 0 brucellosis Ishii, M, C, M 3 1 CO poisoning 1 0 cholera C, C 135 50 dysentery M, M, PT, PT, M 21 12 glanders Ishii, C 22 20 meningitis Ishii, C 5 1 mustard gas 16 16 plague Ishii, C, M, C 180 42 plague (from the Shinkyo [Changchun] epidemic) 66 64 poison 2 0 salmonella M, C 14 11 Songo (epidemic hemorrhagic fever) C, Kitano, C 101 52 smallpox Ishii, C 4 2 streptococcus 3 1 suicide 30 11 tetanus Ishii, PT, C 32 14 tick encephalitis C, Kitano 2 1 tsutsugamushi (scrub typhus) C 2 0 tuberculosis C, Ishii 82 41 typhoid C, C 63 22 typhus C, M, C, Kitano, C 26 9 vaccine 2 2 Total 850 403

Technicians who were civilian employees of the army were treated as officers. The status of civilian employees ranged from infantry-class to general-class, but technicians were treated as lieutenants and above. Ranking below the technicians were operators, clerks, and staff. For the most part, the Ishii network took on university researchers as technicians. The part-time researchers were part-time employees of the Military Medical School Epidemic Prevention Research Laboratory; they were professors at Tokyo and Kyoto imperial universities who were contracted to perform research in their own laboratories. In short, a large number of civilian researchers were mobilized.

Biological Warfare Trials

For the most part, the use of the biological weapons developed by the Ishii network amounted to field trials.

The first of these trials took place during the Nomonhan Incident in 1939. In August, toward the end of the hostilities, pathogens that cause gastrointestinal disease were placed in the Holsten River, a tributary of the Halha River that the Soviet Army used as its source of water. It is not clear how many Soviet soldiers suffered from this attack, but it is thought that casualties were not widespread. This was because the typhoid bacillus and the other pathogens that were used lose their infectivity when placed in water. This fact was known to Ishii’s group. It is thought that they nonetheless carried out the attack because they wanted to conduct a field test of biological weapons in combat. While there were likely few Soviet casualties, at least one Japanese soldier became infected when he spilled liquid from a drum filled with contaminated water while dumping it into the river. He died of typhoid fever at an army hospital in Hailar.

During the following year, 1940, larger scale field trials were conducted in central China, using biological weapons dropped from airplanes. The pathogens were cultivated by Unit 731 and shipped to Unit 1644 in Nanjing, which served as the forward base for the attacks, which continued until 1942. During the first two years, these attacks were carried out in cities along the Chang River. Of these, the large-scale attack on the city of Ningbo on October 27, 1940 is well documented and has also been thoroughly investigated by the Chinese.

The attack took place at 7 a.m. from heavy bombers flying a low-altitude run at 200 meters. The bombers dropped fleas, grain, and strips of cotton on the streets in the center of the city. The fleas were infected with the plague. They had ingested blood from plague-infected rats and were called “plague fleas.” The plague bacteria were not dissipated directly, as it was considered more effective to infect the carrier fleas and release them, in order to target a specific area with a focused attack. It was also expected that the bacteria would live longer in the bodies of the fleas. The fleas were dropped with grain and cotton to ensure that they reached the target area, and it was also thought that the cotton would absorb some of the shock of impact on the ground.

The first death was recorded on the fourth day, October 30, and casualties increased rapidly in the days that followed. By November 2, it was clear that the disease was an epidemic, and the area was sealed off as disease-contaminated. The next day, it was determined that the disease was the plague. By then 37 deaths had been reported. The quarantine imposed on the area slowed the spread of the epidemic.

The plague epidemic ended on December 2 with the death of the last two victims. Deaths totaled 106 people. These figures were reported in a survey, conducted by two Ningbo researchers and published in March 1994 by Dongnan University Press. This historical account of the epidemic tracked down all of the victims and listed them by name, and it is thus a very valuable document.

This attack, killing more than one hundred people, was the most lethal in this series of attacks on Chinese cities. However, when one considers that the attack was carried out by heavy bombers on a risky low-altitude run, these results have to be considered a military failure.

There were two primary reasons for this failure. First, the bacteria used was so infectious that it immediately set off alarms among its victims. Second, the effort suffered from exaggerated expectations of the ability to artificially spark an epidemic. In February 1941 Ishii reported to his superior officer, Lt. Gen. Kajitsuka Ryuji, chief of the medical department of the Kwantung Army: “It is not as easy as some people think, and as I once thought, to deliberately spread infectious disease. While infectious disease spreads readily in natural circumstances, numerous obstacles are encountered when artificially spreading infection, and sometimes great pains must be taken to overcome these.” [2] It was expected that pathogens dropped in a densely populated area like Ningbo would quickly spread person to person, but these expectations were betrayed.

Great Failures

In November 1940, the month after the attack on Ningbo, the Chinese began to take countermeasures in response to biological warfare attacks on urban populations. On November 28, the central Chinese city of Jinhua suffered an attack. The result was a failure. According to a Chinese Ministry of Health document, “At the time that the plague epidemics were continuing in Ningbo and its vicinity, three Japanese airplanes flew over Jinhua and dropped a large number of small granules the size of small shrimp eggs. These strange objects were gathered and examined at a local hospital. . . . They showed the physical characteristics of the bacteria that cause the plague. In any case, the plague did not break out in Jinhua and as far as this town was concerned the Japanese experiment in germ warfare ended in failure.”

No effort was made to collect the material dropped from the airplanes on Ningbo, but one month later the objects dropped on Junhua were gathered and analyzed. There had been rapid progress in securing evidence in response to the attacks. It is also likely that townspeople were warned to stay inside their houses. As a result, the Japanese experiment was deemed a failure.

Biological weapons are not only useful as potent means of war; their use can also be accompanied by an important element of strategic disinformation, if it is claimed that the enemy itself used them, or if it is implied that they were used in retaliation. In this sense, when biological weapons are used, one tactic is to cause confusion as to whether they were used or not, but if the enemy deems the trial uses a failure, the tactic itself fails decisively.

Nonetheless, the trial use of biological weapons on central Chinese cities continued in the fall of 1941. One of the targets was the city of Changde, about 1000 kilometers east of Shanghai in the Chinese interior. The Chinese applied the lessons they learned the previous year and were able to keep casualties in the single digits. Thus the results of the trials through the end of 1941 indicated that dropping plague fleas from airplanes as a means of attacking urban areas was quite ineffective.

Beginning in 1942, Japan began dropping pathogens from airplanes into battlefield zones, on a scale that amounted to a combat operation. In April, Japan launched the Zhejiang campaign. In this campaign, Ishii and company carried out massive biological weapons attacks. Cholera bacteria was the main pathogen employed, and the attacks resulted in more than 10,000 casualties. It has also been reported that some victims contracted dysentery and the plague. More than 1700 soldiers died, mostly from cholera. This would have been considered a great success for the Ishii group, but for the fact that all of the victims were Japanese soldiers.

A Japanese medic captured by American forces at the end of 1944 described the casualties among the Japanese army during his interrogation: “When Japanese troops overran an area in which a [biological weapons] attack had been made during the Chekiang [Zhejiang] campaign in 1942, casualties upward from 10,000 resulted within a very brief period of time. Diseases were particularly cholera, but also dysentery and pest [bubonic plague]. Victims were usually rushed to hospitals in rear. … Statistics which POW saw at Water Supply and Purification Dept Hq at Nanking showed more than 1,700 dead, chiefly from cholera; POW believes that actual deaths were considerably higher, ‘it being a common practice to pare down unpleasant figures.’” [3]

A New Type of Bomb

After the 1942 failure, the Japanese army general staff lost all confidence in the efficacy of biological weapons. The pressure was on to find a new approach that would ensure the safety of friendly troops and deliver a more reliable, more devastating blow to the enemy.

The new approach developed was to pack the pathogens in bombs or shells, which would be dropped from airplanes or delivered by artillery. This would satisfy both of the requirements, to deliver massive carnage while maintaining the safety of the attacking troops. At the same time, the only way to prevent disasters like that of the Zhejiang campaign was to improve communication among the troops.

Two hurdles confronted the effort to load bombs with pathogens. The first was the need to keep the pathogens alive for long periods of time. The second was the need to develop a bomb made of materials that would break apart upon impact using little or no explosives; this would prevent the pathogen from being destroyed by heat. Alternatively, if a bombshell could not be made of fragile material, a pathogen that could withstand the heat of an explosion would have to be selected. When a bomb or a shell lands, people do not immediately gather at the point of impact, so it was necessary to convey the pathogen from that spot to wherever people were. Again a live host like a plague flea that would physically carry the pathogen and infect people was considered the best solution to this problem.

A bacteria bomb using the plague bacteria was developed to satisfy most of these requirements. The bomb used plague fleas packed in a shell casing of unglazed pottery made from diatomaceous earth (a soft, sedimentary rock containing the shells of microscopic algae). This same material was used in a water filter that Ishii had developed and patented. As this bomb would break apart using minimal explosive, it was expected that the plague fleas inside would survive the heat and scatter in all directions, to bite people and spread the disease. This bomb, called the Ishii bacterial bomb, was perfected by the end of 1944. In the beginning of 1945, the collection of rats went into high gear, and Unit 731 went to work cultivating fleas to be infected with the plague.

Japan’s Defeat

The main force of Unit 731 left the unit headquarters by train soon after the Japanese surrender and returned to Japan between the end of August and early September 1945. Some members of the unit and officers of the Kwantung Army were captured by the Soviet military. Twelve of these POWs were tried by the Soviet Union at a war crimes trial in Khabarovsk in December 1949. In addition to members of Unit 731, officers of the Kwantung Army and the army’s chief medical officer were also charged as responsible parties. All of those charged were given prison sentences ranging from two to twenty-five years, but aside from one man who committed suicide just before returning to Japan, all had been repatriated by 1956. The record of the Khabarovsk trial was published in 1950 as Materials on the Trial of Former Servicemen of the Japanese Army Charged with Manufacturing and Employing Bacteriological Weapons (Foreign Languages Publishing House, Moscow).

On the other hand, not one of the members of Unit 731 who returned to Japan was tried as a war criminal. Instead, the American military began investigating the unit in September 1945, and unit officers were asked to provide information about their wartime research, not as evidence of war crimes, but for the purpose of scientific data gathering. In other words, they were granted immunity from prosecution in exchange for supplying their research data. The American investigation continued through the end of 1947 and resulted in four separate reports. The investigation took place in two phases.

The first phase resulted in the Sanders Report (dated November 1, 1945) and the Thompson Report (dated May 31, 1946). These two reports contained information on the unit’s bacteria bombs, but did not address the subject of human experimentation or the trial use of biological weapons. Kitano Masaji, who was in Shanghai at the time of Japan’s surrender, was interrogated in January 1946, but he was instructed by Lt. Gen. Arisue Seizo, the Japanese chief of intelligence, that he should not talk about “human experimentation and biological weapons trials,” Kitano later told this writer. In other words, until that time, these two subjects had been effectively concealed.

4. Body disposal at Unit 731

However, at the end of 1946, American authorities received notice from the Soviets that they intended to try cases involving human experimentation and biological warfare. Ishii and others were interrogated again, and they confirmed the general content of the Soviet claims. The American investigation began anew, headed by new investigators. Two additional reports were produced: the Fell Report (dated June 20, 1947) and the Hill and Victor Report (dated December 12, 1947). These documents described the human experiments conducted by Unit 731 and its related units, based primarily on the interrogation of researchers involved in the experiments.

The Hill and Victor Report concludes with the following evaluation: “Evidence gathered in this investigation has greatly supplemented and amplified previous aspects of this field. It represents data which have been obtained by Japanese scientists at the expenditure of many millions of dollars and years of work. Information had accrued with respect to human susceptibility to those diseases as indicated by specific infectious doses of bacteria. Such information could not be obtained in our own laboratories because of scruples attached to human experimentation.”

The above account makes clear the nature of the crimes committed by the Ishii Unit. At the same, it is necessary to question the responsibility of the American forces who provided immunity from prosecution in exchange for the product of these crimes.

This essay was written by Tsuneishi Keiichi for publication in Sekai senso hanzai jiten (Encyclopedia of world war crimes) (Bungei Shunju, 2002), edited by Hata Ikuhiko, Sase Masamori, and Tsuneishi.

Tsuneishi Keiichi is a Kanagawa University professor specializing in the history of science, and Japan’s leading specialist on biological warfare and Unit 731.

Translated by John Junkerman, a documentary filmmaker living in Tokyo. His most recent film, “Japan’s Peace Constitution,” will be distributed in North America by First Run Icarus Films. He is a Japan Focus Associate. Posted at Japan Focus November 20, 2005.

Tsuneishi Keiichi, 731 Butai: Seibutsu heiki hanzai no shinjitsu (Unit 731: The true story behind the biological weapons crimes) (Kodansha, 1995). Tsuneishi Keiichi, Igakushatachi no soshiki hanzai (The organized crime of medical practitioners) (Asahi Shimbun, 1994; reprinted 1999). Kobayashi Hideo and Kojima Toshiro, eds., 731 saikinsen butai: Chugoku shin shiryo (The bacteriological war unit 731: New Chinese documents) (Fuji Shuppan, 1995). Tanaka Akira and Matsumura Takao, eds., 731 Butai sakusei shiryo (Documents produced by Unit 731) (Fuji Shuppan, 1991). Tsuneishi Keiichi, Mokuteki: Ishii (Target: Ishii) (Otsuki Shoten, 1984).

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A Scientific Method to the Madness of Unit 731’s Human Experimentation and Biological Warfare Program

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Kishor Johnson, A Scientific Method to the Madness of Unit 731’s Human Experimentation and Biological Warfare Program, Journal of the History of Medicine and Allied Sciences , Volume 77, Issue 1, January 2022, Pages 24–47, https://doi.org/10.1093/jhmas/jrab044

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The Japanese Imperial Army Unit 731’s Biological Warfare (BW) research program committed atrocious crimes against humanity in their pursuit of biological weapons development during the Second World War. Due to an American cover-up, the details behind Unit 731’s human experimentation were slow to be revealed. The recent literature discloses the gruesome details of the experiments but characterizes the human trials as crude in nature. Further, there is a lack of clarity as to how human trial results were extrapolated for use in real world missions.

Through an examination of testimony from the Soviet Union’s Khabarovsk War Crime Trials, this paper argues that Unit 731’s inoculation and airborne warfare experiments on prisoners of war were scientifically rigorous. The scientific method is used as the basis against which the scientific rigor of the experiments is tested. The paper reveals that the successes and failures of the human trials were extrapolated to BW missions during the Sino-Japanese war. American researchers’ expectations of BW data were fulfilled, thus paving the way for an immunity deal. Ethical standards in medicine before WWII were not well established, but wartime medical practices and experimentation reveal the context in which the pursuit of scientific knowledge has no boundaries.

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Watch CBS News

Mysterious skulls and skeletons unearthed 35 years ago could be linked to notorious war crimes, Japanese activists say

Updated on: July 26, 2024 / 8:10 AM EDT / CBS/AP

Depending on who you ask, the bones that have been sitting in a Tokyo repository for decades could be either leftovers from early 20th century anatomy classes, or the unburied and unidentified victims of one of the country's most notorious war crimes .

A group of activists, historians and other experts who want the government to investigate links to wartime human germ warfare experiments met over the weekend to mark the 35th anniversary of their discovery and renew a call for an independent panel to examine the evidence.

Japan's government has long avoided discussing wartime atrocities, including the sexual abuse of Asian women known as "comfort women" and Korean forced laborers at Japanese mines and factories, often on grounds of lack of documentary proof. Japan has apologized for its aggression in Asia, but since the 2010s it has been repeatedly criticized in South Korea and China for backpedaling.

Around a dozen skulls, many with cuts, and parts of other skeletons were unearthed on July 22, 1989, during construction of a Health Ministry research institute at the site of the wartime Army Medical School. The school's close ties to a germ and biological warfare unit led many to suspect that they could be the remains of a dark history that the Japanese government has never officially acknowledged.

Headquartered in then-Japanese-controlled northeast China, Unit 731 and several related units injected prisoners of war with typhus, cholera and other diseases, according to historians and former unit members. They also say the unit performed unnecessary amputations and organ removals on living people to practice surgery and froze prisoners to death in endurance tests. Japan's government has acknowledged only that Unit 731 existed.

Led by Gen. Shiro Ishii, Unit 731 researchers "used men and women as involuntary test subjects, causing them unspeakable pain and suffering as they were injected with germs, fed infected foods, and bitten by rodents and fleas," according to the U.S. Naval Institute .

The institute said Unit 731 also produced devices to poison individuals with fountain pens and pointed walking sticks, as well as "techniques for clandestinely poisoning drinking wells." The unit also developed a bomb "that could destroy vegetation in an area of 20 square miles" and experimented with artillery shells carrying gas and biological agents, the institute said.

Top Unit 731 officials were not tried in postwar tribunals as the U.S. sought to get ahold of chemical warfare data, historians say.

"Perhaps the most notorious was Gen. Ishii of Unit 731, who escaped postwar prosecution in exchange, apparently, for supplying the U.S. government with details of his gruesome human experiments," historian Edward Drea wrote in an essay published by the U.S. Archives .

Lower-ranked officials were tried by Soviet tribunals. Some of the unit's leaders became medical professors and pharmaceutical executives after the war.

"We just want to find the truth"  

A previous Health Ministry investigation said the bones couldn't be linked to the unit, and concluded that the remains were most likely from bodies used in medical education or brought back from war zones for analysis, in a 2001 report based on questioning 290 people associated with the school.

It acknowledged that some interviewees drew connections to Unit 731. One said he saw a head in a barrel shipped from Manchuria, northern China, where the unit was based. Two others noted hearing about specimens from the unit being stored in a school building, but had not actually seen them. Others denied the link, saying the specimens could include those from the prewar era.

A 1992 anthropological analysis found that the bones came from at least 62 and possibly more than 100 different bodies, mostly adults from parts of Asia outside Japan. The holes and cuts found on some skulls were made after death, it said, but did not find evidence linking the bones to Unit 731.

But activists say that the government could do more to uncover the truth, including publishing full accounts of its interviews and conducting DNA testing.

Kazuyuki Kawamura, a former Shinjuku district assembly member who has devoted most of his career to resolving the bone mystery, recently obtained 400 pages of research materials from the 2001 report using freedom of information requests, and says it shows that the government "tactfully excluded" key information from witness accounts.

The newly published material doesn't contain a smoking gun, but it includes vivid descriptions - the man who described seeing a head in a barrel also described helping to handle it and then running off to vomit - and comments from several witnesses who suggested that more forensic investigation might show a link to Unit 731.

"Our goal is to identify the bones and send them back to their families," said Kawamura. The bones are virtually the only proof of what happened, he says. "We just want to find the truth."

Health Ministry official Atsushi Akiyama said that witness accounts had already been analyzed and factored into the 2001 report, and the government's position remains unchanged. A key missing link is a documentary evidence, such as a label on a specimen container or official records, he said.

Documents, especially those involving Japan's wartime atrocities, were carefully destroyed in the war's closing days and finding new evidence for a proof would be difficult.

Akiyama added that a lack of information about the bones would make DNA analysis difficult.

Hideo Shimizu, who was sent to Unit 731 in April 1945 at age 14 as lab technician and joined the meeting online from his home in Nagano, said he remembers seeing heads and body parts in formalin jars stored in a specimen room in the unit's main building. One that struck him most was a dissected belly with a fetus inside. He was told they were "maruta" - logs - a term used for prisoners chosen for experiments.

Days before Japan's Aug. 15, 1945 surrender, Shimizu was ordered to collect bones of prisoners' bodies burned in a pit. He was then given a pistol and a packet of cyanide to kill himself if he was caught on his journey back to Japan.

He was ordered never to tell anyone about his Unit 731 experience, never contact his colleagues, and never seek a government or medical job.

Shimizu said he cannot tell if any specimen he saw at the 731 could be among the Shinjuku bones by looking at their photos, but that what he saw in Harbin should never be repeated. When he sees his great-grandchildren, he said, they remind him of that fetus he saw and the lives lost.

"I want younger people to understand the tragedy of war," he said.

• World War II

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Japan's Biological Warfare Project

• Experiments
• Harbin museum
• Yoshio Shinozuka
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Most of us heard about the horrible experiments on humans of the Nazis done by doctor Mengele. But the Nazis weren’t alone in conducting cruel experiments on humans.

One of the lesser known atrocities of the 20th century was committed by the Imperial Japanese Army’s Unit 731. Some of the details of this unit’s activities are still uncovered.

This webpage was set up to collect and organize the information known to date about Unit 731 and present it to anyone interested.

For 40 years, the horrific activities of “Unit 731” remained one the most closely guarded secrets of World War II. It was not until 1984 that Japan acknowledged what it had long denied – vile experiments on humans conducted by the unit in preparation for germ warfare.

Deliberately infected with plague, anthrax, cholera and other pathogens, an estimated 3,000 of enemy soldiers and civilians were used as guinea pigs. Some of the more horrific experiments included vivisection without anesthesia and pressure chambers to see how much a human could take before his eyes popped out.

Unit 731 was set up in 1938 in Japanese-occupied China with the aim of developing biological weapons. It also operated a secret research and experimental school in Shinjuku, central Tokyo. Its head was Lieutenant Shiro Ishii.

The unit was supported by Japanese universities and medical schools which supplied doctors and research staff. The picture now emerging about its activities is horrifying.

According to reports never officially admitted by the Japanese authorities, the unit used thousands of Chinese and other Asian civilians and wartime prisoners as human guinea pigs to breed and develop killer diseases.

Many of the prisoners, who were murdered in the name of research, were used in hideous vivisection and other medical experiments, including barbaric trials to determine the effect of frostbite on the human body.

To ease the conscience of those involved, the prisoners were referred to not as people or patients but as “Maruta”, or wooden logs. Before Japan’s surrender, the site of the experiments was completely destroyed, so that no evidence is left.

Then, the remaining 400 prisoners were shot and employees of the unit had to swear secrecy. The mice kept in the laboratory were then released, which could have cost the lives of 30,000 people, since the mice were infected with the bubonic plague, and they spread the disease.

Few of those involved with Unit 731 have admitted their guilt.

Some caught in China at the end of the war were arrested and detained, but only a handful of them were prosecuted for war crimes.

In Japan, not one was brought to justice. In a secret deal, the post-war American administration gave them immunity for prosecution in return for details of their experiments.

Some of the worst criminals, including Hisato Yoshimura, who was in charge of the frostbite experiments, went on to occupy key medical and other posts in public and private sectors.

Unit 731: The Bunker Of Horrific Terror

The place where the worst human experiments in modern history have taken place.

by Andrei Tapalaga | Jun 8, 2023 | War

The Origins of Unit 731

Unit 731 was established in the early 1930s by the Imperial Japanese Army. Operating under utmost secrecy, it was based in the Pingfang district of Harbin, located in northeastern China. Led by Lieutenant General Shiro Ishii, the unit was primarily tasked with conducting biological and chemical warfare research.

Initially focusing on studying infectious diseases and developing countermeasures, Unit 731’s activities soon escalated to human experimentation on an unprecedented scale. The unit conducted brutal experiments on thousands of prisoners, primarily Chinese and Korean civilians, as well as captured soldiers from various countries.

Unit 731 was not an isolated entity. It collaborated with other units within the Japanese military, such as Unit 100 and Unit 1644, which also engaged in similar heinous activities. These units collectively carried out experiments involving vivisection, frostbite, biological weapon testing, and other forms of torture.

The Horrific Experiments

One of the most chilling aspects of Unit 731’s activities was vivisection, the practice of dissecting live subjects without anesthesia. Prisoners were subjected to excruciating surgeries, often without any medical necessity, as the aim was to study the effects of diseases, wounds, and organ removal on living organisms.

Unit 731 also focused on the development and testing of biological weapons. Prisoners were exposed to lethal pathogens, such as plague, anthrax, and cholera, to study the effects of these diseases and to find ways to weaponize them. These experiments aimed to create bioweapons that could be used against enemy forces.

In addition to vivisection and biological warfare research, Unit 731 subjected prisoners to other forms of inhumane experimentation. These included forced exposure to extreme temperatures to study frostbite, testing the effects of pressure chambers, and conducting experiments on the transmission of diseases through various means.

The Aftermath and Lessons Learned

As World War II came to an end, the atrocities committed by Unit 731 came to light. However, rather than face justice, many of the key personnel involved in the unit’s activities were granted immunity in exchange for sharing their research findings with the United States. This was part of a larger geopolitical strategy, as both the United States and the Soviet Union sought to gain knowledge about biological warfare.

For decades, the atrocities of Unit 731 remained largely concealed. The Japanese government maintained a stance of denial, avoiding acknowledgement or apology for the unit’s actions. It was not until the 1980s that the Japanese government faced pressure from survivors, victims’ families, and international communities to address and take responsibility for the crimes committed.

The existence of Unit 731 raises profound ethical questions about the limits of scientific research and the responsibility of individuals and nations in times of war. The revelations from Unit 731 serve as a reminder of the importance of upholding human rights , respecting the dignity of all individuals, and learning from the mistakes of the past to ensure a more just and humane future.

Unit 731 stands as a horrifying testament to the depths of human cruelty and the unspeakable horrors that can arise during times of conflict. The actions of this secretive unit serve as a haunting reminder of the consequences of unchecked scientific pursuits and the imperative of safeguarding human rights. Remembering the victims and shedding light on the atrocities committed by Unit 731 is crucial in preventing such horrors from being repeated and fostering a more compassionate world.

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Unmasking Horror -- A special report.; Japan Confronting Gruesome War Atrocity

By Nicholas D. Kristof

• March 17, 1995

He is a cheerful old farmer who jokes as he serves rice cakes made by his wife, and then he switches easily to explaining what it is like to cut open a 30-year-old man who is tied naked to a bed and dissect him alive, without anesthetic.

"The fellow knew that it was over for him, and so he didn't struggle when they led him into the room and tied him down," recalled the 72-year-old farmer, then a medical assistant in a Japanese Army unit in China in World War II. "But when I picked up the scalpel, that's when he began screaming.

"I cut him open from the chest to the stomach, and he screamed terribly, and his face was all twisted in agony. He made this unimaginable sound, he was screaming so horribly. But then finally he stopped. This was all in a day's work for the surgeons, but it really left an impression on me because it was my first time."

Finally the old man, who insisted on anonymity, explained the reason for the vivisection. The Chinese prisoner had been deliberately infected with the plague as part of a research project -- the full horror of which is only now emerging -- to develop plague bombs for use in World War II. After infecting him, the researchers decided to cut him open to see what the disease does to a man's inside. No anesthetic was used, he said, out of concern that it might have an effect on the results.

That research program was one of the great secrets of Japan during and after World War II: a vast project to develop weapons of biological warfare, including plague, anthrax, cholera and a dozen other pathogens. Unit 731 of the Japanese Imperial Army conducted research by experimenting on humans and by "field testing" plague bombs by dropping them on Chinese cities to see whether they could start plague outbreaks. They could.

A trickle of information about the program has turned into a stream and now a torrent. Half a century after the end of the war, a rush of books, documentaries and exhibitions are unlocking the past and helping arouse interest in Japan in the atrocities committed by some of Japan's most distinguished doctors.

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The Twisted Story Of Shiro Ishii, The Josef Mengele Of World War 2 Japan

Shiro ishii ran unit 731 and performed cruel experiments on prisoners until he was apprehended by the u.s. government — and granted full immunity..

A few years after World War I, the Geneva Protocol prohibited the use of chemical and biological weapons during wartime in 1925. But that didn’t stop a Japanese army medical officer named Shiro Ishii.

A graduate of Kyoto Imperial University and a member of the Army Medical Corps, Ishii was reading about the recent bans when he got an idea: If biological weapons were so dangerous that they were off-limits, then they had to be the best kind.

Wikimedia Commons Shiro Ishii is often compared to the infamous Nazi doctor Josef Mengele, but he arguably had even more power over his human experiments — and did far more monstrous scientific research.

From that point on, Ishii dedicated his life to the deadliest kinds of science. His germ warfare and inhumane experiments aimed to place the Empire of Japan on a pedestal above the world. This is the story of General Shiro Ishii, Japan’s answer to Josef Mengele and the evil “genius” behind Unit 731.

Shiro Ishii: A Dangerous Youth

Born in 1892 in Japan, Shiro Ishii was the fourth son of a wealthy landowner and sake maker. Rumored to have a photographic memory, Ishii excelled in school to the point that he was labeled a potential genius.

Ishii’s daughter Harumi would later muse that her father’s intelligence might have led him to be a successful politician if he had chosen to go down that path. But Ishii chose to join the military at an early age, showing boundless love for Japan and its emperor all along the way.

Wikimedia Commons From an early age, Shiro Ishii was believed to be a genius.

An atypical recruit, Ishii did well in the military. Standing six feet tall — well above the height of the average Japanese man — he boasted a commanding appearance early on. He was known for his spotlessly clean uniforms, his meticulously groomed facial hair, and his deep, powerful voice.

During his service, Ishii discovered his real passion — science. Specifically interested in military medicine, he worked tirelessly toward the goal of becoming a doctor in the Imperial Japanese Army.

In 1916, Ishii was admitted to the Medical Department of Kyoto Imperial University. In addition to learning both the best medical practices of the time and proper laboratory procedures, he also developed some strange habits.

He was known for keeping bacteria in petri dishes as “pets.” And he also had a reputation for sabotaging other students. Ishii would work in the lab at night after the other students had already cleaned up — and use their equipment. He would purposely leave the equipment dirty so the professors would discipline other students, which led them to resent Ishii.

But while the students knew what Ishii had done, he was apparently never punished for his actions. And if the professors somehow knew what he was doing, it almost seemed as if they were rewarding him for it.

It’s perhaps a sign of his growing ego that shortly after reading about biological weapons in 1927, he decided that he would become the best in the world at making them.

Shiro Ishii’s Immodest Proposal

Wikimedia Commons Special Naval landing forces of the Imperial Japanese Navy prepare to advance during the Battle of Shanghai in August 1937 — with gas masks firmly in place.

Shortly after reading the initial journal article that inspired him, Shiro Ishii began to push for a military arm in Japan that focused on biological weapons. He even directly pleaded with top commanders.

To truly grasp the scale of his confidence, consider this: Not only was he a lower-ranking officer suggesting military strategy, but he was also proposing the direct violation of relatively new international laws of war.

At the crux of Ishii’s argument was the fact that Japan had signed the Geneva agreements, but had not ratified them. Since Japan’s stance on the Geneva agreements was technically still in limbo, there was perhaps some wiggle room that would allow for them to develop bioweapons.

But whether Ishii’s commanders lacked his vision or nebulous grasp of ethics, they were skeptical of his proposal at first. Never one to take no for an answer, Ishii asked for — and ultimately received — permission to take a two-year research tour of the world to see what other countries were doing in terms of biological warfare in 1928.

Whether this signaled legitimate interest on the part of the Japanese military or simply an effort to keep Ishii happy is unclear. But either way, after his visits to various facilities across Europe and the United States, Ishii returned to Japan with his findings and a revised plan.

A Receptive Audience

Wikimedia Commons The Japanese soldiers bombed Chongqing, China from 1938 to 1943.

Despite the Geneva Protocol, other countries were still researching biological warfare. But, out of either ethical concerns or fear of discovery, no one had yet made it a priority.

So in the years preceding World War II, Japanese troops began to seriously consider investing their resources in this controversial weaponry — with the goal that their battle techniques would surpass all other countries on Earth.

By the time Ishii returned to Japan in 1930, a few things had changed. Not only was his country on track to wage war against China, nationalism as a whole in Japan burned a little brighter. The old country slogan of “a wealthy country, a strong army” was echoing louder than it had in decades.

Ishii’s reputation had also grown. He was appointed professor of immunology at the Tokyo Army Medical School and given the rank of major. He also found a powerful supporter in Colonel Chikahiko Koizumi, who was then a scientist at the Tokyo Army Medical College.

Wikimedia Commons Japanese army surgeon Chikahiko Koizumi. After World War II, he came under suspicion for being a war criminal, but he committed suicide before he could be properly investigated.

A veteran of World War I, Koizumi oversaw research into chemical warfare beginning in 1918. But around this time, he almost died in a lab accident after being exposed to a chlorine gas cloud without a gas mask. After his full recovery, he continued his research — but his superiors placed a low priority on his work at the time.

So it’s no surprise that Koizumi saw himself reflected in Shiro Ishii. At the very least, Koizumi saw someone similar enough to him who shared his vision for Japan. As Koizumi’s star continued to rise — first to Dean of the Tokyo Army Medical College, then to Army Surgeon General, then to Japan’s Minister of Health — he made sure that Ishii moved up along with him.

For Ishii’s part, he certainly enjoyed the praise and promotions, but nothing seems to have been more important to him than his own self-aggrandizement.

Ishii’s public work consisted of researching microbiology, pathology, and vaccine research. But as all those in the know understood, this was only a small part of his actual mission.

Unlike his student years, Ishii was rather popular as a professor. The same personal charisma and magnetism that had won over his teachers and commanders also worked on his students. Ishii often spent his nights out drinking and visiting geisha houses. But even while inebriated, Ishii was more likely to go back to his studies than to go to bed.

This behavior is telling on two counts: It shows the kind of obsessive man Ishii was, and it explains how he was able to persuade others to help him with his deranged experiments after he began working in China.

A Secret, Sinister Facility

Xinhua via Getty Images Unit 731 personnel conduct a bacteriological trial upon a test subject in Nongan County of northeast China’s Jilin Province. November 1940.

Following the invasion of Manchuria in 1931 and the establishment of the puppet client state Manchukuo shortly thereafter, Japan utilized the region’s resources to fuel its industrialization efforts.

Like the attitudes of Americans during the “Manifest Destiny” period of expansion, many Japanese soldiers saw the people living in the area as obstacles. But to Shiro Ishii, these residents were all potential test subjects.

According to Ishii’s theories, his biological research would require different types of facilities . For instance, he established a biological weapons facility in Harbin, China, but quickly realized that he wouldn’t be able to freely conduct involuntary human research in that city.

So he simply began to put together another secret facility that was about 100 kilometers south of Harbin. The 300-home village of Beiyinhe was razed to the ground to make way for the site, and local Chinese laborers were drafted to construct the buildings.

Here, Shiro Ishii developed some of his barbaric techniques, foreshadowing what would come in the notorious Unit 731.

Wikimedia Commons Unit 731’s Harbin facility was built on Manchurian land conquered by Japan.

The sparse records from the Beiyinhe facility offer a sketch of Ishii’s work there. With up to 1,000 prisoners crammed into the facility, the test subjects were a mixed group of underground anti-Japanese workers, guerrilla bands who harassed the Japanese, and innocent people who unfortunately got caught in a roundup of “suspicious persons.”

A common early experiment was drawing blood from prisoners every three to five days until they were too weak to go on, and then killing them with poison when they were no longer considered valuable to research. Most of these subjects were killed within a month after their arrival, but the number of total victims in the facility remains unknown.

In 1934, a prisoner rebellion broke out as the soldiers celebrated the Mid-Autumn Festival. Taking advantage of the guards’ drunkenness and the relatively lax security, some 16 prisoners were able to successfully escape. This is the main reason why we know what we do about that facility.

Despite the extreme risk to the security and secrecy of the operation, it’s possible that experiments continued at that site as late as 1936, before it was officially shut down in 1937.

Ishii, for his part, did not seem to mind the closure. He was already getting started with another facility — which was far more sinister.

The Josef Mengele Of Japan

Xinhua via Getty Images Unit 731 researchers conduct bacteriological experiments on captive child subjects in Nongan County of northeast China’s Jilin Province. November 1940.

Shiro Ishii is often compared to Josef Mengele, the German doctor known as the “Angel of Death,” who conducted sinister experiments in Nazi-occupied Poland.

The infamous Auschwitz-Birkenau concentration camp was a complex that killed its prisoners as part of its design. While many victims were executed in gas chambers, others were reserved for Mengele and his twisted medical experiments.

As an SS officer and member of the Nazi elite, Mengele had the authority to determine the fitness of prisoners, recruit imprisoned medical professionals as assistants, and force inmates into becoming his test subjects.

But unlike Ishii, Mengele was more limited in his power over the camp and in the effectiveness of his research. Auschwitz had been built to produce rubber and oil, and Mengele used the environment to conduct pseudoscience. His work fell under the guise of genetics , but it was often little more than pointless and cruel acts of sadism.

In many ways, Ishii had more control over his human subjects. His research was also more scientific — and monstrous. Just about all the horrors that occurred in the facilities had been thought up by Ishii — with the intention of turning human beings into data.

Expanding and building upon his earlier efforts, Ishii designed Unit 731 to be a self-sufficient facility, with a prison for his human subjects, an arsenal for making germ bombs, an airfield with its own air force, and a crematorium to dispose of human remains.

In another part of the facility were the dormitories for Japanese residents, which included a bar, library, athletic fields, and even a brothel.

But nothing at the complex could compare to Ishii’s house in Harbin, where he lived with his wife and children. A mansion left over from the period of Russian control over Manchuria, it was a grand structure that was remembered fondly by Ishii’s daughter Harumi. She even likened it to the home in the classic film Gone With The Wind .

Shiro Ishii And The Experiments At Unit 731

Xinhua via Getty Images The frostbitten hands of a Chinese person who was taken outside in winter by Unit 731 personnel for an experiment on how to best treat frostbite. Date unspecified.

If you know the name Unit 731, then you probably have some idea of the horrors that unfolded at Ishii’s facility — believed to be set up around 1935 in Pingfang. Despite decades of cover-up, stories of the cruel experiments that took place there have spread like wildfire in the age of the internet.

However, for all the discussion of freezing limbs, vivisections, and high-pressure chambers, the horror that tends be ignored is Ishii’s inhumane reasoning behind these tests.

As an army doctor, one of Ishii’s primary goals was the development of battlefield treatment techniques that he could use on Japanese troops — after learning just how much the human body could handle. For example, in the bleeding experiments, he learned how much blood the average person could lose without dying.

But at Unit 731, these experiments kicked into high gear. Some experiments involved simulating real-world conditions.

For example, some prisoners were placed in pressure chambers until their eyes popped out so that they could demonstrate how much pressure the human body could withstand. And some prisoners were injected with seawater to see if it could work as a replacement for a saline solution.

The most horrifying example touted around the internet – the frostbite experiment — was actually pioneered by Yoshimura Hisato, a physiologist assigned to Unit 731. But even this test had a practical battlefield application.

Unit 731 researchers were able to prove that the best treatment for frostbite was not rubbing the limb — the traditional method up until that point — but instead immersion in water a bit warmer than 100 degrees Fahrenheit (but never hotter than 122 degrees Fahrenheit). But the way they came to this conclusion was horrific.

Unit 731 researchers would lead prisoners outside in freezing weather and leave them with exposed arms that were periodically drenched with water — until a guard decided that frostbite had set in.

Testimony from a Japanese officer revealed that this was determined after the “frozen arms, when struck with a short stick, emitted a sound resembling that which a board gives when it is struck.”

When the limb was struck , this sound would apparently let the researchers know that it was sufficiently frozen. The frostbite-affected limb was then amputated and taken to the lab for study. More often than not, the researchers would then move on to the prisoners’ other limbs.

When prisoners were reduced to heads and torsos, they were then handed over for plague and pathogen experiments. Brutal as it was, this process bore fruit for Japanese researchers. They developed an effective frostbite treatment several years ahead of other researchers.

As with Mengele, Ishii and the other Unit 731 doctors wanted a wide sample of subjects to study. According to official accounts, the youngest victim of a temperature-changing experiment was a three-month-old baby .

The Brutality Of Weapons Testing

Xinhua via Getty Images A Unit 731 doctor operates on a patient that is part of a bacteriological experiment. Date unspecified.

Weapons testing at Unit 731 took several distinct forms. As with medical research, there were “defensive” tests of new equipment, such as gas masks.

Researchers would force their prisoners to test out the effectiveness of certain gas masks in order to find the best kind among the pack. Although unconfirmed, it is believed that similar testing led to an early version of the bio-hazard protection suit.

In terms of offensive weapons tests, these tended to fall under two different categories. The first was the deliberate infection of prisoners to study disease effects and to select suitable candidates for weaponization.

In order to better understand the impacts of each disease, researchers did not provide prisoners with treatment and instead dissected or vivisected them so that they could study the impact of the diseases on the internal organs. Sometimes, they were still alive while they were being cut open.

In a 1995 interview, one anonymous former medical assistant in a Japanese Army unit in China revealed what it was like to cut open a 30-year-old man and dissect him alive — without any anesthetic.

“The fellow knew that it was over for him, and so he didn’t struggle when they led him into the room and tied him down,” he said. “But when I picked up the scalpel, that’s when he began screaming.”

He continued, “I cut him open from the chest to the stomach, and he screamed terribly, and his face was all twisted in agony. He made this unimaginable sound, he was screaming so horribly. But then finally he stopped. This was all in a day’s work for the surgeons, but it really left an impression on me because it was my first time.”

The second type of offensive weapons testing involved the actual field testing of various systems that dispersed diseases. These were used against prisoners within the camp — and against civilians outside of it.

Ishii was diverse in his exploration of disease dispersal methods. Inside the camp, prisoners infected with syphilis would be forced to have sex with other prisoners who weren’t infected. This would help Ishii observe the onset of the disease. Outside the camp, Ishii gave other prisoners dumplings that were injected with typhoid and then released them so they could spread the disease.

He also passed out chocolates filled with anthrax bacteria to local children. Since many of these people were starving, they often didn’t question why they were receiving this food and unfortunately assumed it was just an act of kindness.

Sometimes, Ishii’s men would use air raids to drop innocuous items like wheat and rice balls and strips of colored paper above nearby cities. It was later discovered that these items were infected with deadly diseases.

But as horrific as these attacks were , it was Ishii’s bombs that truly placed him at the top of all other biological weapons researchers.

A “Gift” To Mankind

Xinhua via Getty Images Japanese personnel in protective suits carry a stretcher through Yiwu, China during Unit 731’s germ warfare tests. June 1942.

Ishii’s plague bombs carried an unusual payload. Instead of the usual metal containers, they would use containers made of ceramic or clay so that they would be less explosive. That way, they would be able to properly release plague-infected fleas on countless people.

Unable to improve off of the traditional means of spreading the “Black Death,” Ishii decided to skip the rat middleman. When his bombs exploded, the surviving fleas would quickly escape, seeking out hosts to feed on and spread the disease.

And that’s exactly what happened in China during World War II. Japan dropped these bombs on both combatants and innocent civilians in multiple towns and villages.

But Ishii’s master plan, “Operation Cherry Blossoms at Night,” intended to use these weapons against the United States .

If this plan would’ve succeeded, about 20 of the 500 new troops who arrived in Harbin would’ve been taken toward southern California in a submarine. They would’ve then manned an onboard plane and flown it to San Diego. And plague bombs would’ve then been dropped there in September 1945.

Thousands of disease-riddled fleas would’ve been deployed, as the troops took their own lives by crashing somewhere onto American soil.

However, America’s atomic bombings happened before this plan came to fruition. And the war ended before the operation was even fully mapped out. But ironically enough, it was America’s interest in Ishii’s research that ultimately saved his life.

In August 1945, shortly after the atomic bombings of Hiroshima and Nagasaki, the order came to destroy all evidence of the activities at Unit 731. Shiro Ishii sent his family ahead by railroad, remaining behind until his infamous facilities were destroyed.

The exact number of people killed by Unit 731 and its related programs remains unknown, but estimates usually range from about 200,000 to 300,000 (including the biological warfare operations). As for deaths due to human experimentation, that estimate typically ranges around 3,000. By the end of the war, any remaining prisoners were speedily killed off.

Although Ishii was also ordered to destroy all documentation, he carried some of his lab notes out of the facility with him before going into hiding in Tokyo. Then, the American occupation authorities paid him a visit.

Throughout the war, vague reports from China about unusual outbreaks and “plague bombs” had not been taken very seriously until the Soviets took Manchuria from the Japanese. By that point, the Soviets knew enough to have a vested interest in finding and securing General Ishii to “interview” him about his infamous research.

For better or for worse, the Americans got to him first. According to Ishii’s daughter Harumi, the American officers used her as a transcriber as they interrogated her father about his work.

At first, he played coy, pretending not to know what they were talking about. But after he secured immunity, protection from the Soviets, and 250,000 yen as payment, he began to talk.

All told, he’d revealed 80 percent of his data to the United States by the time of his death. Apparently, he took the other 20 percent to his grave.

A Deal With The Devil

Wikimedia Commons Unit 731 bombs on display at a museum on the site of where the Harbin bioweapon facility used to be.

In order to protect Ishii and maintain a monopoly on his research, the United States kept its word. The crimes of Unit 731 and other similar organizations were suppressed, and at one point they were even labeled “Soviet Propaganda” by American authorities.

And yet, a “top secret” cable from Tokyo to Washington in 1947 revealed: “Experiments on humans were … described by three Japanese and confirmed tacitly by Ishii. Ishii states that if guaranteed immunity from ‘war crimes’ in documentary form for himself, superiors, and subordinates, he can describe program in detail.”

To put it plainly, American authorities were eager to learn the results of experiments that they weren’t willing to perform themselves. That’s why they granted him immunity.

Although some of the research from Ishii was valuable, American authorities didn’t learn nearly as much as they thought they would. And yet they kept their end of the bargain. Shiro Ishii lived out the rest of his days in peace until he died of throat cancer at the age of 67.

Years after the agreement, North Korea made a startling allegation that the United States had dropped plague bombs on them during the Korean War.

And so a group of scientists from France, Italy, Sweden, the Soviet Union, and Brazil — led by a British embryologist — toured the affected areas to collect samples and issue a verdict in the 1950s.

Wikimedia Commons A page from the International Scientific Commission for the Facts Concerning Bacterial Warfare in China and Korea. Allegations that America used biological warfare during the Korean War remain controversial to this day.

Their conclusion was that germ warfare had indeed been used as North Korea claimed. Officially, this is also “Soviet Propaganda,” according to the United States. Or is it?

With a clear answer still missing, we are left with uncomfortable questions. Consider the following: In 1951, a now-declassified document showed that the U.S. Joint Chiefs of Staff issued orders to begin “large scale field tests… to determine the effectiveness of specific BW [bacteriological warfare] agents under operational conditions.” And in 1954, Operation “Big Itch” dropped flea bombs at the Dugway Proving Ground in Utah.

With that in mind, what is more likely? Are these actions coincidental to the Chinese and Soviets using part of the truth that they knew in an attempt to embarrass the Americans? Or, did someone secretly give the order to bring Shiro Ishii and his men out of retirement?

In any case, one thing is clear. Shiro Ishii never faced justice and died a free man in 1959 — all thanks to the United States deal with the Devil.

After reading about Shiro Ishii, the unhinged mind behind Unit 731, learn the full story of Operation “Cherry Blossoms at Night.” For a glimpse of what the operation may have looked like, check out the mysterious “Battle of Los Angeles” that may have been started by a Japanese balloon bomb.

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The True Story Behind Japan’s WWII Human Experiment Division

The 20th Century is full of examples of man’s inhumanity to man. The horrors of the first World War early in the century set the stage for what was to become one of the darkest periods in human history. And no event serves as a more terrible reminder of how evil people can be than the atrocities that followed in the second World War.

The crimes of Nazi Germany in occupied territories and the industrial slaughter of the Holocaust resulted in the deaths of millions of people. But the second World War was truly a global conflict and evil was found everywhere it was fought.

Though they often get less popular attention than those of the Germans, the Japanese military’s crimes were certainly horrific. The occupation of Nanking by the Japanese Army led to a maelstrom of violence that lead to tens or possibly even hundreds of thousands of deaths among the residents of the city.

Like the Germans, the Japanese often treated the citizens in occupied territories with almost casual cruelty. Also like the Germans, the Japanese even exploited these people for horrific human experimentation . They even had a specialized unit they created to conduct these experiments: Unit 731.

The story of Unit 731 really began before the Second World War with the person who would eventually lead the unit’s activities, Shiro Ishii . Ishii was a medical officer in the Japanese military who specialized in studying infectious diseases. This kind of research was a popular subject for Japanese Army researchers like Ishii, who realized the importance of keeping troops healthy in the field. But Ishii also realized that infectious diseases could be turned against an enemy’s troops and began to advocate that the military look into developing biological weapons.

In 1930, Ishii petitioned the government for funding to form a research team that would study the effects of pandemic diseases. The government agreed and Ishii began work at the “Epidemic Prevention Research Laboratory,” where he claimed publicly to be working on ways to protect Japanese troops from diseases. This was actually true in one sense. Much of Ishii’s work was dedicated to researching effective ways to treat and prevent infectious diseases. However, Ishii’s actual intentions were always far darker. He wanted to learn which diseases would be the best candidate for weaponization.

With the permission of his direct superiors in the military, Ishii began to look for ways to turn his knowledge of preventing diseases towards finding ways to spread them. Ishii began testing various diseases on animals to see which spread quickly and killed efficiently in the hopes of finding the perfect biological weapon . However, Ishii felt that what he really needed to achieve his goal were human subjects. Because his research unit operated in Tokyo, ethical concerns and fears of containing the diseases he was testing prevented him from acquiring these subjects. However, events would soon provide him with the opportunity he needed.

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In 1931, a Japanese military officer placed dynamite near the tracks of a Japanese-owned railway line in the region of Manchuria in North-East China. The resulting explosion did little actual damage, but officers in the Japanese Army seized the opportunity and blamed Chinese saboteurs for the attack that they themselves had engineered. Using the event as a pretext, they launched an invasion, quickly taking control of the region from the Chinese. The Chinese government, which didn’t want a war with Japan, offered little resistance and Japan set up a puppet government under the last Qing Emperor of China, Puyi .

Shiro Ishii recognized the opportunity to collect subjects from the civilian population of Manchuria and moved to Zhongma Fortress near the city of Harbin in Manchuria. There, Ishii organized a secret research group called the “Togo Unit” and began his research in earnest. During the occupation, the Japanese Army and secret police frequently arrested Chinese civilians and resistance fighters, as well as common criminals. Many of these prisoners ended up in Zhongma fortress, where they fell under the control of Ishii and the Togo Unit.

Ishii began to test the effects of various diseases on his human subjects. Under the guise of giving them vaccines, prisoners were injected with different bacteria or viruses to see how long it took for them to become infected. After the infection set in, the prisoners were monitored to see how the disease developed compared to other prisoners. In many cases, prisoners were then cut open while still alive to study the effects of the disease on their internal organs. Those who didn’t die from these tests were executed.

In 1934, a prisoner at Zhongma managed to overpower a guard and take his keys. He then freed forty of his fellow prisoners and scaled the walls of the fortress. Many of the prisoners attempting to escape were shot or recaptured, but a few managed to get away and spread the word of what was going on inside the prison. This escape and loss of secrecy lead Ishii and his superiors to close down their research at Zhongma and move to a new facility. There, the unit acquired the name by which it is most well-known: Unit 731. And there, they continued their horrific experiments.

Unit 731 was able to continue getting its supply of fresh subjects through the Japanese secret police, the Kempeitai. The Kempeitai arrested Chinese civilians on trumped-up charges of “suspicious activities” at the behest of Unit 731, which gave them instructions on whom to arrest. Ishii wanted to make sure that his subjects reflected the general population, so pregnant women, children, and the elderly were all arrested on these sorts of charges and brought to Ishii’s facility for tests on the effects of different diseases. And because Ishii wanted to test the effects of disease on different races of people, the large Russian community in Harbin was frequently targeted by the Kempeitei. In Ishii’s eyes, everyone was a potential subject for his twisted experiments.

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Ishii’s goal was always to find an effective biological weapon, so he investigated some of the most virulent diseases in human history. Many of his tests focused on the bubonic plague , which killed millions during the Middle Ages. He wanted to find ways to spread the plague quickly, which meant testing the best way to infect large numbers of people with the disease. Ishii ordered plague-infected fleas to be dropped from airplanes onto cities in China, leading to minor epidemics that killed thousands. In addition to fleas, Unit 731 dropped clothing or food infected with cholera and anthrax, leading to more epidemics and thousands of deaths.

But Unit 731 didn’t limit its research to just weaponizing disease, they also tested the effects of different injuries to the human body. Prisoners were often subjected to freezing temperatures to study the effects of frostbite, as guards beat them to determine how much feeling was left in their frozen limbs. The injuries were then left untreated to study the effects of gangrene, as the prisoner’s fingers or limbs began to rot and fall off. Other prisoners were subjected to experiments testing the effects of grenades from different ranges, and even flamethrowers. Obviously, few survived these types of tests.

Unit 731 was also very interested in venereal diseases, like syphilis or gonorrhea. Often, prisoners were infected with these diseases to test the effects and treatments. But these prisoners were also forced under threat of death to have sex with uninfected prisoners so that researchers could study how the diseases were transmitted from one person to another. They also wanted to study whether or not pregnant women could transmit a venereal disease to their fetus; thus women were sometimes forcibly impregnated for these tests.

Prisoners were also subjected to stranger experiments that reflect the callous disregard for human life shown by Unit 731. It was as though they simply wanted to satisfy their morbid curiosity. Prisoners were strapped into centrifuges that spun them at high speeds until they died. Others were injected with animal blood or seawater, simply to see how their body might respond. Still, others were bombarded with X-rays to study the effects of radiation. Some were simply buried alive or burnt to death. And others were denied food or water to see how long it took them to die.

Ultimately, Ishii’s experiments accomplished little. The Japanese never managed to develop a biological weapon that could turn the tide of the war. And Ishii’s attempts to pressure the Japanese military to use biological weapons in the Pacific were rebuffed several times. The only serious attack ever planned was to target the city of San Diego. However, this last desperate plan was aborted due to Japan’s surrender in 1945. After the surrender, Ishii was granted immunity by the American occupation forces in exchange for handing over his research. Ishii never stood trial for his crimes and lived out the rest of his days in Japan before dying of throat cancer years later. The fact that Ishii and other members of Unit 731 escaped prosecution truly rank among the worst failures of justice in history.

Inside Unit 731 and Japan’s Human Experiments in WW2

From 1939 to 1945, the world witnessed the deadliest war in history, as over 30 countries wound together in acrimony, strife, and bloodshed, leading to a war that claimed the lives of more than 100 million people all over the world. History reveals that the war was replete with different subplots, each significantly ravaging our shared humanity.

But of all these battlefronts, the Pacific Theatre, hosting the most extended series of battles during WW2, stands tall as the epicenter of the action.

Historians recorded that Japan started the war when it launched an attack on Manchuria in 1931 and invaded China in 1937. This invasion was instantly followed by disturbances and upheavals that shook China’s very foundations, culminating in a civil war and famine that claimed the lives of over 63 million persons, lasting until China’s liberation in 1945.

Imperial Japan did unleash unspeakable terror on China during its occupation. Still, all these are nothing compared to the atrocities perpetrated in Unit 731 – the very center-point of Japanese biological warfare units that plunged the already genocidal war into newer depths of horror.

What started as a research and public health agency with a noble, innocent beginning descended into an abyss of terror when Unit 731 grew an assemblage for weaponized diseases that could have killed every living thing on earth multiple times over if deployed to its maximum strength.

This rather sordid shift in purpose was designed for the eternal suffering of captives as disease incubators and test subjects which very well served its purpose until 1945 when Unit 731 shut down operations.

But before then, Unit 731 had committed some of the most degrading and torturous human experiments in human history.

Frostbite Tests

Perhaps, assigning Yoshimura Hisato to Unit 731 marked the beginning of doomsday for the Chinese captives. Here was a physiologist with an uncanny obsession for hypothermia, whose curiosity had no limits and who had almost no regard for human life.

Attempting to improve on Maruta’s research on limb injuries, Hisato submerged the limbs of Chinese captives in water and ice and held them until the limb – arm or leg – had frozen with visible ice coatings on the skin. Eye witness accounts say the limbs sounded like wood when hit with a plank. But for Hisato, this was only the beginning. 

He attempted different methods to rewarm the frozen limbs as rapidly as possible. In some cases, he would douse the limb with hot water; other times, he would hold the limbs close to an open fire. And sometimes, he would leave the subject untreated overnight to examine how long it would take for the subject’s blood to break off the frost.

Maruta and the Throes of Vivisection

Established as a research unit, Unit 731 was preoccupied with investigating how disease and injury affect the fighting ability of armed forces. However, “Maruta,” an arm of the Unit, went rogue when it took up the research by a notch, breaking the defined bounds of medical ethics, though, at that point, it only observed injuries and disease courses on patients.

The project began with volunteers from the Army, but as the experiments scaled new highs and the supply of volunteers ran out, the Unit soon turned its attention to Chinese prisoners of war and captives. Consent became a thing of the past, and there was no limit to what researchers could do.

At this point, Unit 731 referred to their confined research subjects as “Murata” or “logs.” Needless to say, the study methods deployed for these experiments were highly dehumanizing.

Vivisection, one of the most common practices in those days, deserves special mention here. This was a process whereby human bodies were mutilated without anesthesia to conduct studies and experiments in living systems.

In those days, thousands of persons, primarily Chinese captives, elderly farmers, and children, who suffered diseases such as the plague and cholera, had their organs removed and examined.

This was mainly to study the possible effects of their various diseases before their body decomposes after death. In some instances, subjects had their limbs detached and reattached to another half of their body, while some had their limbs frozen, crushed, or cut off to study the spread of gangrene in the body.

When a subject’s body had exhausted its use, they would drive lethal injections into their body or shoot them even while some were buried alive. None of these Unit 731 subject captives survived this dehumanizing confinement, whether Chinese, Korean, Russian, or Mongolian.

Atrocious Weapons Tests

In every war, weapons superiority is a central talking point for superpowers. The Japanese knew this, only that they took it too seriously.

As the war raged, the effectiveness of weapons manufactured became a significant question and an area of interest to the Army. As part of efforts to determine the potency of their weapons, Unit 731 huddled captives together within a firing range.

It blasted shots at them from different ranges using Japanese weapons such as bolt-action rifles, Nambu 8mm, machine guns, grenades, and pistols. In assessing the varying levels of effectiveness, researchers compared wound patterns and depths of penetration to dying inmates and actual deaths.

Traditional weapons like knives, swords, and bayonets were equally studied, except in this case, the victims were usually bound. Unit 731 also tested flamethrowers on covered and open skin, while gas chambers were built at strategic unit facilities to expose test subjects to blister agents and nerve gas.

Victims were bound in one place as heavy objects dropped on them to study crush injuries, while test subjects were wound up and deprived of food and water to learn how long the average human can survive without water.

In most cases, these victims drank only seawater or were impaled with injections of mismatched animal or human blood to analyze the process of transfusion and clotting.

Prolonged exposure to x-ray sterilized and maimed thousands of research subjects while inflicting severe burns in cases where the emitting plates are miscalibrated or placed too close to the participants’ genitals, faces, or nipples.

Unit 731 also studied the effects of high G-forces on pilots and falling paratroopers. They loaded human beings into large centrifuges, spinning them at extremely high speeds until they lost consciousness or died, typically at 10 to 15 G’s. They found that young children were more tolerant of acceleration forces.

Syphilis Studies on War Captives

History has shown that venereal diseases have inflicted major disruptions on organized armies since ancient Egypt. In attempting to prevent similar occurrences, the Japanese military took an interest in studying the symptoms and treatments of syphilis.

For a start, doctors at Unit 731 infested test subjects with syphilis, withheld treatments, and observed the progress of the illness.

However, Salvarsan, a primitive chemotherapy agent and contemporary treatment in those days, was administered within a specified period to assess the side effects of the disease.

Male subject carriers of syphilis were asked to rape male and female captives to ensure the disease was effectively transmitted.

The infected prisoners were closely monitored to observe the onset and spread of the illness. Where the first exposure resulted in zero infection, more subjects were raped until the infection was established.

Rape and Systematic Pregnancy

You may consider the syphilis experiment far too outrageous, but it probably pales compared to the spate of rape and forced pregnancy that characterized Unit 731’s operations.

The most common instance includes female captives being raped and systematically impregnated so that trauma and weapon experiments could be carried out on them.

These women were advertently infected with life-threatening diseases, doomed to crush injuries, chemical weapons exposure, shrapnel injuries, and bullet wounds.

After this, Unit 731 doctors opened up the pregnant subjects and studied the effects of these injuries on the fetuses.

It appears the ultimate objective was to transpose the findings into contemporary medicine, but even if Unit 731 researchers had published these findings, the papers might not have survived the war.

Fleas and Plagues on Chinese Civilians

As time passed, it became clearer that Japan’s Unit 731 was driven by an ultimate mission to develop weapons of mass destruction by 1939, to ravage the Chinese people, and destroy Allied forces, if time permitted.

The Unit rounded up tens of thousands of captives caged across different facilities in Manchuria, which imperial forces had occupied for decades.

The Japanese infected these inmates with the most lethal virus and pathogens science has ever known. Prominent examples of such deadly pathogens include yersinia pestis, which causes the pneumonic and bubonic plague , and typhus, which the researchers systematically spread from one inmate to another to depopulate notable areas.

The doctors bred the most dangerous strains and monitored patients as they advanced through various stages, from symptoms to spread. When victims survived, they were shot, and the sickest were left to bleed on the mortuary table if they fell ill.

The doctors would take their blood would infect other captives, and the sickest from this group would be bled to transfect the deadliest strain to another group of prisoners.

Once, a member of Unit 731 pitched the idea that the sickest captives should be spread out on a slab with a line inserted into their carotid artery.

That’s not all – when the blood has been sucked out of their heart which would be too weak to pump more blood, a military officer will jump on the victim’s chest with his leather boots. The officer did this with so much force and vigor that it crushed the captive’s ribcage, and blood would spurt into a designated container.

One of the significant plagues bred by the Unit – plague bacillus – was built into a vastly lethal pathogen. The last set of subjects was exposed to an overwhelming huddle of fleas.

These fleas were packaged and sealed with clay bomb casings. On 4th October 1940, Japanese bombers released these casings, each containing 30,000 blood-sucking fleas that were initially exposed to the prisoners in a Chinese village called Quzhou.

According to eyewitnesses, the bombing was accompanied by fine crimson dust settling on different surfaces of the town and a succession of terrible flea bites that ravaged everyone present.

A series of eyewitness accounts agreed that at least 2,000 Chinese civilians died of the plagues foisted by these fleas, with 1,000 more deaths in a nearby village called Yiwu after sick railway staff carried the pathogen to this location. Unit 731 also employed anthrax to launch this attack, killing at least 6,000 people.

As the war tailed to an end, Japan tried to bomb America with the same fleas, but to no avail. But this was perhaps the beginning of the end for Unit 731 because by August 1945, Hiroshima and Nagasaki had been bombed, and the Soviet Army invaded Manchuria and annihilated the Japanese Army. The emperor then read his surrender memo over the radio and disbanded Unit 731.

The research records and reports were burnt, and all the data and information generated by the Unit in 13 years were equally destroyed.

Some researchers returned to everyday civilian life in Japan as if nothing had happened, with some venturing into academics and medicine.

Some quarters believe that vestiges of the experiment may have found their way into academia and may have played significant roles in building war and medical technologies today.

However, these ideas are mere conjectures that thrive on the possibility that bits of information from inside Unit 731 may have escaped the 1945 purge.

But here’s what we know for sure: World War 2 is such a deadly detour in human history, and at the very center of the Pacific Theatre in Manchuria, humanity was bent backward – a thousand times and over, and for 13 solid years.

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The New York Times

Sinosphere | a new look at japan’s wartime atrocities and a u.s. cover-up, a new look at japan’s wartime atrocities and a u.s. cover-up.

Joy Chen is sitting on a bench outside a new museum about the medical atrocities committed by Japan’s Unit 731 in Manchuria during World War II, trying to absorb what she learned inside: After the war, the United States covered up Japan’s biological warfare research on humans, allowing the perpetrators to escape punishment and to prosper.

That is detailed prominently in exhibition notes and an audio guide in the black marble building that lies like a split box here in Pingfang, on the edge of Harbin in northeast China: “Out of considerations of its national security, the U.S. decided not to prosecute the leader of Unit 731 and the criminals under him. They all escaped trial for war crimes.”

Led by Dr. Shiro Ishii , Unit 731 bred plague microbes, then deliberately infected thousands of men, women and children. It conducted vivisection and frostbite and air pressure experiments, transfused prisoners with horse blood and studied the effect of weapons on the body, among many things.

Ms. Chen had had her fill of horrors and left her two companions inside.

“I’m shocked,” said Ms. Chen, 24, who studies English at the Harbin Institute of Foreign Languages . “I couldn’t take more. As a Chinese person I just felt it was so incredibly cruel.”

“And I found out for the first time about the Americans. Why didn’t they prosecute them? I felt that was really hard to accept. Definitely, Chinese people will feel that way,” she said.

“It is shocking, isn’t it,” said Mark Selden , a historian at Cornell University, in a telephone interview.

“It is precisely correct, as far as we know. No one was prosecuted. A deal was cut for the rehabilitation of everyone,” Mr. Selden said.

That enabled the United States to gather information that was of great use for its own biological warfare program, early in the Cold War, he said.

In contrast, many Nazi doctors in Europe who did similar things were prosecuted by the Nuremberg war crimes tribunal.

The American action in Japan “was in some ways similar to how Wernher von Braun and other scientists were taken to the U.S.,” said Mr. Selden, referring to the German rocket scientist. “The U.S. made very good use of them.”

“In Japan, they did want the biological warfare research and they did take it. You and I may wonder if it was a wise thing to do, but the reality is that there was no significant pushback,” he said.

The Museum of War Crime Evidence by Japanese Army Unit 731 , which opened on Aug. 15, is bolder in intent than the older, adjacent museum that it incorporates and replaces and, according to museum officials, has attracted large crowds of visitors.

Judging by Ms. Chen’s reaction, its blunt declaration of the cover-up is having some impact and could one day raise a difficult question: Should the United States apologize to China?

Those calls, for now mostly on the nationalist fringe, could grow if the relationship between the two nations worsens.

There are also serious historians and bioethicists who believe what happened is morally too significant and damaging to humanity to be excused. Jing-Bao Nie at the University of Otago in New Zealand is one.

“Morally, the cover-up trampled justice in the ruthless pursuit of national interest and national security,” Mr. Nie wrote in an email.

“Legally, the cover-up constitutes complicity after fact,” he said. “And pragmatically, a formal apology will serve the long-term interest of the United States because it can contribute positively to the relationship between the U.S. and China.”

That last may be needed one day, Mr. Selden said: “We are at a period in which there are a lot of tensions in the relationship.”

Yet for now, anger in China is directed almost entirely toward Japan, he said.

“I’ve often been struck by the unrestrained anger toward the Japanese, far beyond anything toward the U.S. Even if we are in a period of many frictions,” he said.

Follow Didi Kirsten Tatlow on Twitter @dktatlow .

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