Pathogen and freezing experiments were the kindest experiments practiced by Unit 731. Its Nazi counterpart was almost humane compared to it. The Nazis engaged in mainly high altitude/low pressure testing, freezing, and some biowar tests. The Japanese Unit 731 committed far worse atrocities, not excluding the areas that the Nazis researched in, but they also dissected and vivisected patients while they were still alive, without anesthetic for "research" purposes. They performed this not only on Chinese peasants but also American and Russian POW's.

These experiments were very well-documented, and yet the Americans exchanged the information for the freedom of the doctors, who practiced their grisly "art" with pleasure. They infected prisoners with various diseases then proceeded to carve them open while still alive to see the results. There are even photographs of them doing this. Over 3000 people were killed by Unit 731 alone in medical experiments.

In addition to this, Unit 731 also performed field tests of both biological and conventional weapons. They tested their weapons on live prisoners after letting them loose in a field. They also used planes to drop plague and other diseases all over China, in areas that have already been conquered by the Japanese. Historians estimate that around 200,000 Chinese died in these experiments.

And that's not all. Rookie doctors practiced surgery on live patients, then killed them afterwards. A favorite of these "doctors" was raping Chinese girls then dissecting them alive later to see the development of the fetus. They even photographed themselves doing this and kept it in their wallets. Unit 731 attempted a final scheme, codenamed "Cherry Blossoms at Night", in 1945 to launch plague at California. The plan was abandoned when Japan surrendered. They then used dynamite to blow up all the evidence.

Here is the explanation given by an anonymous farmer in Japan who participated in Unit 731: "Vivisection should be done under normal circumstances. If we'd used anesthesia, that might have affected the body organs and blood vessels that we were examining. So we couldn't have used anesthetic."

Oh yeah, they experimented on children too, but the doctors claimed that "their fathers were probably spies". Just thinking about the fact that the Americans let these butchers go unpunished makes me sick.

Lasciate ogni speranza, o voi ch’entrate
—Dante Alighieri, inscription above the Gate of Hell

From a century with world war, massacres, and genocides, it is sometimes easy to become almost numbed by horror and atrocity. Man's inhumanity to man has a long black history, the only "progress" seems to be his ability to come up with more efficient, more technological, more "clever" ways to conduct it.

Sometimes it isn't so much the horrors one knows, but the one's that have largely remained hidden (at least in the West). Everyone knows what is referred to when the name Auschwitz is uttered. Precious few know what hides behind the seemingly innocuous name of "Unit 731." If such things are not given exposure, then the cry of the holocaust, "never again," will fail and the horror continue to be repeated throughout the rest of history.

Essentially, Unit 731 was a Japanese group located in occupied China during the Second World War that experimented with biological weapons (there were others,—most notably Unit 100 and another located in Nanking/Nanjing—Unit 731 was the largest and main facility). But it went much further than that. The experiments were performed on Chinese civilians and prisoners of war from Russia, Korea, and the allies (including the United States). And the experiments were more than just testing killing potential, they included vivisection, dissection, frostbite experiments, poison gas, testing of conventional weapons on the victims, and other things. Though exact numbers are not known, at least 3000 died just between 1940 and the end of the war (it opened in 1936)—possibly as high as 9000.

Perhaps the worst part was not the experiments themselves but that few were held accountable for it and many of those responsible went on to "good" lives and well-paying successful careers following the war. Facilitated by the United States (a more in depth write-up on that aspect is pending).


Chemical/biological warfare has a history going back earlier than the twentieth century. Even before the germ theory of disease was worked out, infected bodies (or parts) of plague victims were used against foes in sieges. While it did not begin as intentional, the Europeans in the New World infected the indigenous peoples in huge numbers. They became quickly aware that proximity to sick westerners made the Indians sick and far worse than it affected those from Europe—this was knowingly used to their advantage in Latin America.

There is also the notorious Lord Jeffrey Amherst incident where Indians were intentionally given small pox infected blankets. Despite having no knowledge of the concept of viral infection, evidence shows that people were aware that those who spent time with those infected or in buildings or among personal effects could certainly catch it.

Conventions against biological weapons
International prohibitions against chemical-biological warfare date at least as far back as the Convention with Respect to the Laws and Customs of War on Land (Hague, II; entered into force in 1900), in which it states that it is "especially prohibited" to (among other things) "employ poison or poisoned arms" or to "employ arms, projectiles, or material of a nature to cause superfluous injury" (article 23). It also includes sections on treatment of civilians, prisoners of war, and the surrendered and wounded. It was reiterated in the Hague Convention (IV; 1907, entered in force 1910) using almost identical wording (it was then "especially forbidden").

The use of poison gas during World War I, gave even more cause to outlaw the use of such substances and techniques. That led to the Geneva Protocol to the Hague Convention in 1925 (entered in force in 1928). Titled the Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare, it states that "the use in war of asphyxiating, poisonous or other gases, and of all analogous liquids, materials or devices, has been justly condemned by the general opinion of the civilised world" with the desire that "this prohibition shall be universally accepted as a part of International Law, binding alike the conscience and the practice of nations." It also extends the "prohibition to the use of bacteriological methods of warfare."1

This, of course, did not stop some countries from working on the weapons (then or years later up to the present).

Ishii Shiro
Throughout the twenties, Japan had been interested in the potential of biological weapons of war (it first began to study the subject as early as 1918). In 1928, Ishii Shiro, who had both medical and Ph.D. degrees from Kyoto Imperial University (and a rising career in the Army Medical Corps), took a trip to Europe. While there as a "military attache," he was able to gather information on other countries' biological programs or potential. He was convinced that this use of science and technology would be the way to win in future wars. On his return, he championed the cause to his superiors. He went on to head the unit.

There is evidence that suggests Shiro was conducting human experiments even before the unit was established, as construction near the site of the Medical Military College in Tokyo unearthed human remains. Forensics experts believe the bones were "Mongoloid," though not Japanese. There was no further investigation.

With the "September 18, Incident" (Mukden Incident2) in 1931, Japan forcefully occupied Manchuria. The following year they set up a puppet government called Manchukuo. Now Japan had a location for its biological warfare unit—it had been established in 1932 as the Epidemic Research Laboratory in Japan with Shiro in charge. In 1932, they chose a location about 20 km (12.42 miles) south of Harbin, China—the location called Pingfan. The first germ weapons research facility, named the Kamu Unit (later Togo) was set up in 1933.

Under imperial decree, two facilities were set up in the area in 1936. Unit 731 (which was also sometimes called Manchukuo Unit 731) began life as the Epidemic Prevention Department of the Kwantung Army (later adding "Water Purification" to the title). Unit 100 was first the Wakamatsu Unit, named for its commander, then Department of Veterinary Disease Prevention of the Kwantung Army.3

Unit 100 was largely involved with crop and livestock diseases—one plan was release diseased cattle in with area livestock so that when the Russians invaded, as was expected, they might eat the cattle or contact would cause epidemics among the soldiers and the locals. It also manufactured large quantities of diseases, only the lack of adequate equipment and supplies keeping them from the projected totals of 1000 kg (2,204 lb.) of anthrax per year, among others. Human experimentation took place but on a much smaller scale. In 1941, both were given their better known names.

The area was evacuated by the occupying army, creating a 32 sq. km (12.35 sq. mile) "no man's land" where the facility could be built. Using Chinese citizens as forced labor, the compound was built. Over the course of Unit 731's history, some 10,000 Chinese were treated as slave labor and at least 3000 died. Many of those that worked on the main buildings became the first batch of test subjects.

The facility took up about 6 sq. km (2.3 sq. miles) and had about 150 buildings. It had a staff of 3000 (though medical students and doctors were brought over to visit, observe, "learn," and practice throughout its history). It is estimated that the various units had a combined personnel of 20,000.


The name Maruta was given to the internees of the camp. It means "log" and gives a clear picture of the way these human beings were viewed by the people running the unit. They were nothing but objects for use—useful but disposable and plentiful as needed.

Not only a reflection of the attitude toward them but a way that made it easier to perform the experiments (especially for the newer people or visitors) as it dehumanized them. And dehumanization along with tolerance to take part in the activities there. As one doctor testified later: "The first time I was very hesitant to do what I was told to do. The second time you get used to it. The third time you volunteer." He also stated that "when I studied at the medical facility, I killed 14 Chinese alive. At the time, to me it was like killing a dog." At the time the victims were being dehumanized so they could be used as a means to an end (a strong streak of racism was also widespread among the ranks), the doctors were surrendering all their humanity as well. Without that, they were dealing with nothing more sentient than firewood.

The Marutas were easily rounded up since Japan had control over the region. The army, military police, and others could easily procure more victims. They came from all demographics. There were anti-Japanese, communists, patriotic Chinese, prisoners of war: Allies, Americans, Koreans, Russians. They were also whoever was convenient when more were needed—people picked up off the street.

The majority were young men in good health (since they were both testing for the effectiveness in killing the enemy and trying to determine how to protect the Japanese soldiers) but older people, women, and children were all used. In one documented case, a three day old infant, was plunged into water lowered to the freezing point for thirty minutes. To keep its hand open—instead of instinctively clenching which would give poor reading on the equipment—a needle was stuck into its finger.

The chief area of research at the unit was concerned with biological warfare, specifically the testing of various diseases and the best way through which to expose the enemy to them. A secondary goal of testing of various vaccines and cures (both for helping make the weapons more deadly and to provide protection for Japanese soldiers) was also important. It was held by Shiro that the main reason for the different research was the impending battle against Russia that was thought to be imminent.

One of the favorites was the plague. It was liked for its ability to be transmitted as an epidemic without the appearance of it being a tactical weapon. The unit bred both rats and the fleas that carried the disease. It was capable of producing 300 kg (661.38 lb.) of plague bacteria per year and 45 kg (99.2 lb.) of fleas every two to three months—the production goal was ten billion fleas. They also reportedly discovered a way of drying and preserving the bacteria that not only made it easier to disperse but even more toxic.

Typhoid, cholera, and various dysentary-producing germs were also tested and mass-produced. Again, it would be harder to suspect they were weapons and not the result of a "natural" epidemic. The toxins would be introduced into water supplies and spread the "normal" way as well as through other means, such as sprays and bombs. Much research was done on making bombs and other things that could spread the germs more effectively.

One of the ways they tested these weapons was in specially built "houses" where Marutas would be led and imprisoned, then exposed to rats or a bomb (with enough cushioning or protection to survive the initial detonation). Then they would be carefully monitored to see how long it took for the onset of the symptoms and for death. Another experiment involved detonation of a bomb full of "gangrene germs" near some who were protected except for their legs and buttocks. "Infected" shrapnel tore into the exposed skin and within seven days, they died in agony. Sometimes injections were used or the germs were put into food, drink, or cigarettes (one case used melons). Sometimes parts of their body would be cut open for direct application of germs. If anyone escaped infection, they were used again for another experiment.

One specially built lab had a four hundred prisoner capacity. There were windows in the doors so that the progressive symptoms and deaths could be monitored and studied. Doctors would stand outside taking notes and holding stopwatches. Reputedly, no one who entered came out alive.

To test vaccines, varying dilutions of the vaccine was used to determine its ability to protect the subject. Again the victims were closely monitored and then autopsied after death. In some cases they would be killed at various stages of the disease in order to examine the progress of the destruction to the body's different organs. Some subjects would be infected and "cured" over and over until they were no longer in any condition to be useful for experimentation and then were disposed of (there were three well-used incinerators at the unit). Some infections were treated using different medical procedures (or left to run their course) to determine the best means to treat them. If a "patient" died, he would be examined, dissected and disposed of—there were always more test subjects.

There are records (some pictures that are said to be of the dissection of the subjects) of experiments with syphilis and other sexually transmitted diseases. STDs were a problem with many soldiers on the front due to extensive use of "comfort women" (forced prostitution that often turned into violent gang rape or extended periods of activity that led to the death of the woman). While it's likely that the diseases were from the soldiers, the frequent use of the victims by so many men led to their spread. Some women were intentionally infected in order to test different methods of treatment. Some reportedly were impregnated by personnel, then infected, and the mother and child dissected for study.

Testing and use of chemical weapons was far less extensive than the biological aspect was. On the other hand, the "attention" to detail was no less exacting. Use of poison gas was tested against Marutas. One experiment had Chinese staked around some local terrain, some wearing protection, some not. Clouds of gas were released over a four day period and the results observed. In a similar experiment using germ bombs, several of the Marutas freed themselves and others, attempting to flee on foot. The soldiers got into trucks and ran them down. Both those killed and not-quite-killed were tossed onto the trucks and sent for dissection.

Marutas were forced to drink liquid mustard gas, causing intense pain, vomiting, and diarrhea. It was also manufactured into a spray and used on their skin and eyes. High enough doses caused blindness; skin damage would progress through large fluid-filled blisters that would burst, leading to ulcers. Experiments with various cyanide combinations were also worked on

This section understandably overlaps some of the others and concentrates on dissection/vivisection.

Perhaps the most ghastly element of the activities at the unit was the extensive medical experiments and dissections that took place on dead and living victims. In most cases, those that died from whatever other experiment being performed were taken and carefully autopsied, organs weighed and examined, in many cases saved. Testimony from former personnel describes an extensive collection of labeled specimen jars of various sizes full of organs, body parts, and even heads and brains.

One description was of a Russian victim, bisected at the waist. Supposedly jars were also sent elsewhere for continued study. Dissections on non-Asians were also done in order to determine whether the methods being used would work on caucasians. This was why prisoners of war were important for the experiments (besides as fresh victims). A former worker claimed seeing jars labeled to say that the parts were Americans, Englishmen, and Frenchmen.

In addition to its military uses, the medical experiments were used for research. Women were used for (possibly dubious?) research on the reproductive system. It was said that female dissections earned the largest audiences. It was also something of a "teaching hospital," with medical students brought in from Japan for "practice." In fact, one doctor (quoted above) testified that the "live dissections were just for practice, not medical research." More (grammatical typos from source):

During vivisection, we brutally performed spinal block or general anesthesia. After victims become unconscious, I practice appendectomy, arms and legs amputation, and bronchial opening with feather insertion for cleaning a chest with bullet.... Another time, we practice surgery on bullet-shot victims at the surgery table without using any anesthesia. We did not treat Chinese as living human beings.

Administering anesthesia was often a matter of soaking gauze in it and holding it over the victim's mouth and nose. As noted, in numerous cases, none was used (many felt that the anesthetic would affect the organs and make accurate examination and study difficult or impossible) and descriptions of victims screams and needing to be held down (in most cases they were already restrained) are found in testimony from former personnel. One assistant described one such procedure:

This guy already knew he was going to die. So when they tied him down, he did not fight. When I picked up the scalpel, he began to shout. With one cut I sliced open his chest and stomach. The pain was so intense that his face contracted. His screams were horrendous, unimaginable. Finally, he quieted down.

Finally, they all quieted down one way or another.

Amputation experiments were also performed, usually on those exposed to gangrene (or who had developed it from other experiments) or the frostbite victims (see below). These would also be done with or without anesthesia.

Another unit testimonial describes a kidnapped ten year old who was vivisected. So "fresh" was the victim that "the organs were still contracting and making soft murmurs." Someone noted that "the organs are still alive." Everyone then laughed. Every organ was removed from the chest and abdominal cavity, as was the brain.

Perhaps the most frightening bit of testimony comes from a doctor who is faced with a numbness about what happened and the loss of his humanity:

"There are times when I look at my hands and remember what I have done with these hands. What is really scary is that I don't have any nightmares of what I have done."

Many other experiments, some almost certainly without any medical or research purpose, took place at the unit. Many frostbite/hypothermia experiments took place. People were exposed to temperatures of -30ºC (-22ºF) for twenty to sixty minutes then put into baths of water at various temperatures to determine the best method of treatment (Nazis did similar experiments in the concentration camps). This often led to "amputation or rotting." Another method of the experiment was to expose the victim to freezing temperatures outside, and then plunging the limbs into cold water until the victim had frostbite. In order to know that the frostbite was sufficient for their purposes, they would knock a rod against the limb until it sounded like it was hitting a piece of wood.

Dehydration and deprivation (food and/or water) experiments were performed. Some people were sweated to death. Others were electrocuted (some had lightning made to strike them) or boiled alive. Pressure and motion experiments were done. The people in the pressure chamber would have their eyes rupture from their sockets and blood would come out through the skin pores. People were spun in large centrifuges until dead. They were exposed to X-rays, hung upside down until dead, and had air injected into their veins. In all cases, there was extensive study and examination accompanied by autopsy and preservation.

Blood experiments took place where the blood of a Maruta would be "siphoned off and replaced with the blood of horses in plasma experiments." People were beaten with different objects and weapons to see how each damaged skin and muscle.

Military experiments using regular ordnance also took place. Firebombs were tested for effectiveness while burning trapped victims alive. They were shot in the head from different angles and the brains examined to see how they were damaged. Rifles were tested to see how many enemy soldiers could be shot through with a bullet. Maintaining the painstaking attention to the details and conditions, the victims would be placed at varying distances and fitted with different uniforms and clothing.

There are probably many other experiments that took place at Unit 731 and the other units. Without access to documents and testimony (what wasn't destroyed or has been suppressed), they may remain unknown to history.

There were almost 1500 allied prisoners of war that eventually were taken to the units, over 1100 were Americans. Treated much the same as the Marutas, by 1943 (according to various eyewitness accounts by other prisoners) almost 700 had died. An Australian doctor recorded an incident in his journal where 150 Americans were marched away and never returned. Others reported being infected or deprived of essentials.

That all this criminally violated the Geneva Convention should go without saying.

Outside the camps
Not only were the weapons developed in the units tested within them, they were actively used outside of them. Starting in 1937, the Japanese army used poison gas over one thousand times in China. There are at least six occasions when they dropped plague bacteria out of airplanes on Chinese cities. Other pathogens were also used against the Chinese. It was widespread (and lacking control) enough that, in some cases, Japanese soldiers were infected leading to a number of casualties (one claim is as high as 1700).

Cherry Blossoms at Night
Not only were there plans to use the weapons in the expected invasion of Russia, but other allies, as well—particularly the US. In 1944, plans were considered to attempt to expose the US mainland to biological warfare. One possibility was use balloons carrying the bacteria, accompanied by an explosive device which would detonate and spread the pathogen. Using balloons as weapons was eventually tried, using regular ordnance and killing seven people (in order to keep panic from spreading, US news reports were censored).

In 1945, the operation named "Cherry Blossoms at Night" was conceived. They would sneak submarines carrying small aircraft near the coast and have kamikaze pilots infect city populations (San Diego is mentioned as a target) with plague fleas. The target date was late September. Whether or not this plan would have been implemented is difficult to determine and since the war ended a month earlier, it will never be known. The Japanese did have submarines with small aircraft that could have been dispatched. On the other hand, Japan's priority and the all the best equipment and ordnance were being saved for defense of Japan, itself.

The war ends

Destroying the evidence
With the dropping of the atom bomb on Hiroshima and the expected surrender of Japan, the men of Unit 731 needed to evacuate and destroy evidence of what took place there. It was sped by the 8 August invasion of Russia. On the ninth (the day the second bomb was dropped), they began dynamiting the equipment, labs, and buildings. Any remaining Marutas were killed. Some were poisoned, some machine-gunned. Personnel began a mass incineration of bodies and the body part-samples—when the incinerator became choked with human remains, they began tossing the rest in the river. Others were burned in a large pit and the remains collected and dumped in the river. Originally, the plan (by Shiro) was for personnel to take cyanide and die there. This was not implemented.

Documents were burned, test and breeding animals were killed, and the members of Unit 731 fled. Unfortunately not all the rats were killed. Many were released into the region, causing an epidemic that some estimate killed as many as 20,000.

The chemicals and toxins left the area polluted and there is concern even today about the danger the diseases and other weapons left behind can pose. As late as 1982, some construction workers were injured when they unearthed a container of poison gas.

The legacy of the crimes did not end with the destruction of the bases and evacuation of the personnel. Not only did the area remain polluted and hazardous for decades, but it lived on in the men who engineered this holocaust of the Pacific Theater. Men who were not tried (twelve were by the Russians in 1949, getting sentences from two years to twenty-five—with the exception of a suicide, all had been released by 1956), not punished and many becoming prominent members and professors at colleges and universities and heads of companies.

To date (February 2002), the only "punishment" handed down by the US—which gave them immunity in return for their "secrets"—has been the Department of Justice listing of sixteen Japanese men as war criminals (only some of whom were part of the unit, the others were for other reasons), making them unable to set foot on American soil. Calls for reparations have also been denied or ignored. Other possible Japanese war criminals might also be barred entrance but the Japanese government is "reluctant" to turn over Imperial Army records.

As "punishment" goes, it seems merely a wrist slap.

A detailed look at the the subsequent immunity given to those involved and the cover-up of what happened:
Unit 731: the cover-up

(None of this is meant to condemn or implicate the Japanese people as a whole, but rather actions taken by groups of individuals who happened to be Japanese. Cruelty, brutality, and inhumanity cut across all demographics and national borders).

1Japan never ratified it. Interestingly, it took the United States fifty years to ratify it.

2The incident was instigated by the Japanese army. it involved a dynamiting of Japanese-owned train tracks (an explosion that conveniently did very little damage to the rails). It was used as a pretense for the Japanese to occupy all of Manchuria.

3There are different variations on the exact wording of the unit names (before they were numbered) depending on the source. I assume this is a result of translation. They remain close enough that it should cause no problem.

(Sources: all quotes from there;,,,,

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