Kept a secret for over 40 years, Unit 731 was exposed in 1984 when a graduate student at Keio Medical University in Tokyo found records of human experiments in a bookstore. The pages described the effects of massive dosages of tetanus vaccine. There were tables describing the length of time it took victims to die and recorded the muscle spasms in their bodies.
After the Mancurian Incident (the official Japanese occupation of Manchuria) occurred in September of 1931, Japan proclaimed a “sovereign state” Manchukuo which was ruled by the puppet emperor ( and last emperor of China) Pu-Yi. Manchuria was the perfect place to set up a unit which would research the effects of biological and chemical warfare and how to use them effectively as a weapon against Japan’s enemies. Far from the main island of Japan, Manchuria was the perfect secret location. The project of Unit 731 was first set up in the city of Harbin, but was destroyed after a group of prisoners blew up the laboratory forcing Ishii to find another suitable location. Unit 731’s title for the public was “Epidemic Prevention and Water Supply Unit of the Kwantung Army” seeming harmless and rather proactive.
On August 1, 1936 Ishii was given formal command of the Unit. After the Marco Polo Bridge Incident in 1937 Japan’s war in China escalated. The laboratory in Pingfan was set in three square kilometers of land and the facilities were hidden by a high wall, and protected by many high voltage wires. The land had around one hundred and fifty buildings, including housing for those captured, and incinerator, an animal house, and air field. From an aerial view blocks 7 and 8 were hidden from the naked eye, these buildings however were the hotspots for bacteria production and research. A young recruit describes his first impression of Pingfan:
“…the central building towering skyward over other building, with all square-tiled facades, were larger than any of those I had observed on my trip over, including Osaka, hsinking and Harbin. these buildings reflecting the sunlight glistened in brilliant white and broke into the vast sky. High earth walls were constructed with barbed wire fencing atop. It was obvious that this compound was isolated strictly from the outside world.”
Unit 731 was broken into eight different divisions
- 1st Division- Bacteriological research
- 2nd Division- Warfare research and field experiments
- 3rd Division- Water filter production
- 4th Division- Bacteria mass production and storage
- 5th Division- Educational division
- 6th Division- Supplies division
- 7th Division- General Affairs
- 8th Division- Clinical Diagnosis
The secrecy of Unit 731 always remained a priority for the operation. Members of the unit were transported in and out of Pingfan in covered cargo trucks, while the trucks registration tags never remained the same, being changed for protection frequently. When researching which method was best to disperse a virus or disease, Ishii arrived at the conclusion that dispersing internal pathogens in water supplies would be much more effective than by air dispersion. Pingfan was producing three hundred kilograms of plague germs and bacteria at one point. At Unit 731’s height the production plant had the capacity to create enough bacteria to kill the entire world’s population several times over. In 1941 Ishii discovered his greatest ally, the flea. Ishii understood that fleas ingest around five thousand plague organisms once feeding from a rat suffering from disease and “when the flea stops sucking blood from it’s victim, may drive back into the bite wound highly infective blood. The infective flea may regurgitate as many as ten thousand to twenty four thousand organisms at one biting. Some of these usually enter the blood of the new host who, if susceptible, contracts bubonic or septicemia plague. Ishii found that an infective flea, with its blocked gullet could live and carry its deadly bit for up to one month and a single bit was found to be sufficient to cause infection.” Innocent Chinese who had been captured were the patients to such tests.
Ishii’s “Secret of Secrets” was kept from thousands of employees at Unit 731. Prisoners would pass through tunnel entrances to the “death blocks” of blocks seven and eight, never to return again. The only thing guaranteed when entering either of these blocks was death and pain. The reason Ishii chose the remote location of Manchuria was in order to test specifically on live human subjects. Ishii accumulated most of his subjects from a detention camp called Hogoin in Pingfan. Russians who would not cooperate and give any information after being house at Hogoin would be sent straight to Unit 731. Though, seventy percent of the humans used were Chinese. “Unsuspecting and innocent people were also tricked into the clutches of Unit 731. Some were lured by the prospect of employment. Young boys, mothers and children, even pregnant women, were trapped”. Throughout the existence of Unit 731 in Pingfan, three thousand people were sacrificed. ” The prison was a vision of hell. Through the syphole cut in the steel doors of each cell, the plight of the chained prisoners could be seen. Some had rotting limbs, bits of bone protruding through skin blackened by necrosis. Others were sweating in high fever, writhing in agony or moaning in pain. Those who suffered from respiratory infections coughed incessantly. Some were bloated, some emaciated, and others were blistered or had open wounds. Many of the cells were communal. An infected person would be put with healthy prisoners to see how easily diseases spread. In desperation prisoners would try to practice primitive preventive medicine to escape contagion”. Female prisoners were raped daily and was almost routine among the guards. The doctors used various methods of dispersing the diseases. They could be sprayed invisibly, in gas chambers, or in food, drink, chocolates, melons, or crackers
Dr. Sueo Akimoto, a young serologist sent from the Tokyo Imperial University in Manchuria recalls what he saw when first arriving ” I was very shocked when I arrived and found out about the human experiments. Very few of those scientists had a sense of conscience. They treated the prisoners like animals. The prisoners were the enemy, they would eventually be sentenced to death. They thought the prisoners would die and honorable death if, in the process, they contributed to the progress of medical science…I was very frightened although my work involved no human experiments. I wrote my resignation to Maj-Gen Kikuchi, the research chief, three or four times. But there was no way to get out. I was told that if I left I might secretly be executed.”
This unit showed no remorse and carried out some of the most heinous experiments in human history on men, women, children, and infants. More than 10,000 civilian and military personnel were subjected to human experimentation. The West knew about it but said nothing.
A special project code-named Maruta used human beings for experiments. Test subjects were gathered from the surrounding population and were sometimes referred to euphemistically as “logs” (丸太? maruta), used in such contexts as “How many logs fell?”. This term originated as a joke on the part of the staff because the official cover story for the facility given to the local authorities was that it was a lumber mill. However, in an account by a man who worked as a junior uniformed civilian employee of the Japanese Army in Unit 731, the project was internally called “Holzklotz”, which is the German word for log. As if in accordance to the dark humor shared among the units members, victims of the experiments were burned like “logs” after they have supposedly ran their course.
The test subjects were selected to give a wide cross-section of the population and included common criminals, captured bandits and anti-Japanese partisans, political prisoners and also people rounded up by the Kempeitai military police for alleged “suspicious activities”. They included infants, the elderly and pregnant women.
Thousands of men, women and children interned at prisoner of war camps were subjected to vivisection, often without anesthesia and usually ending with the death of the victim. Vivisections were performed on prisoners after infecting them with various diseases. Researchers performed invasive surgery on prisoners, removing organs to study the effects of disease on the human body. These were conducted while the patients were alive because it was feared that the decomposition process would affect the results. The infected and vivisected prisoners included men, women, children, and infants.
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’ limbs were frozen and amputated, while others had limbs frozen, then thawed to study the effects of the resultant untreated gangrene and rotting.
Some prisoners had their stomachs surgically removed and the oesophagus reattached to the intestines. Parts of the brain, lungs, liver, etc., were removed from some prisoners.
Japanese army surgeon Ken Yuasa suggests that the practice of vivisection on human subjects (mostly Chinese communists) was widespread even outside Unit 731, estimating that at least 1,000 Japanese personnel were involved in the practice in mainland China.
Germ warfare attacks
Prisoners were injected with diseases, disguised as vaccinations, to study their effects. To study the effects of untreated venereal diseases, male and female prisoners were deliberately infected with syphilis and gonorrhoea, then studied. Prisoners were also repeatedly subject to rape by guards.
Plague fleas, infected clothing and infected supplies encased in bombs were dropped on various targets. The resulting cholera, anthrax and plague were estimated to have killed around and possibly more than 400,000 Chinese civilians. Tularemia was tested on Chinese civilians.
Unit 731 and its affiliated units (Unit 1644 and Unit 100 among others) were involved in research, development and experimental deployment of epidemic-creating biowarfare weapons in assaults against the Chinese populace (both civilian and military) throughout World War II. Plague-infested fleas, bred in the laboratories of Unit 731 and Unit 1644, were spread by low-flying airplanes upon Chinese cities, coastal Ningbo in 1940, and Changde, Hunan Province, in 1941. This military aerial spraying killed thousands of people with bubonic plague epidemics.
Physiologist Yoshimura Hisato conducted experiments by taking captives outside, dipping various appendages into water, and allowing the limb to freeze. Once frozen, which testimony from a Japanese officer said “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'”, ice was chipped away and the area doused in water. The effects of different water temperatures were tested by bludgeoning the victim to determine if any areas were still frozen. Variations of these tests in more gruesome forms were performed.
Doctors 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:
“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 cover the body with only eyes and mouth visible, 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. Testimony from multiple guards blames the female victims as being hosts of the diseases, even as they were forcibly infected. Genitals of female prisoners that were infected with syphilis were called “jam filled buns” by guards.
Some children grew up inside the walls of Unit 731, infected with syphilis. 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.” 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.
Rape and forced pregnancy
Female prisoners were forced to become pregnant for use in experiments. The hypothetical possibility of vertical transmission (from mother to foetus or child) of diseases, particularly syphilis, was the stated reason for the torture. Foetal survival and damage to mother’s reproductive organs were objects of interest. Though “a large number of babies were born in captivity”, there has been no account of any survivors of Unit 731, children included. It is suspected that the children of female prisoners were killed or the pregnancies terminated.
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 bacteriological or physiological experiments, sex experiments, and the victims of sex crimes. The testimony of a unit member that served as guard graphically demonstrates this reality:
“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.”
Human targets were used to test grenades positioned at various distances and in different positions. Flamethrowers were tested on humans. Humans were tied to stakes and used as targets to test germ-releasing bombs, chemical weapons, and explosive bombs.
In other tests, subjects were deprived of food and water to determine the length of time until death; placed into high-pressure chambers until death; experimented upon to determine the relationship between temperature, burns, and human survival; 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.
Japanese researchers performed tests on prisoners with Bubonic plague, cholera, smallpox, botulism, and other diseases. This research led to the development of the defoliation bacilli bomb and the flea bomb used to spread bubonic plague. Some of these bombs were designed with porcelain shells, an idea proposed by Ishii in 1938.
These bombs enabled Japanese soldiers to launch biological attacks, infecting agriculture, reservoirs, wells, and other areas with anthrax, plague-carrier fleas, typhoid, dysentery, cholera, and other deadly pathogens. During biological bomb experiments, researchers dressed in protective suits would examine the dying victims. Infected food supplies and clothing were dropped by airplane into areas of China not occupied by Japanese forces. In addition, poisoned food and candies were given out to unsuspecting victims, and the results examined.
In 2002, Changde, China, site of the flea spraying attack, held an “International Symposium on the Crimes of Bacteriological Warfare” which estimated that at least 580,000 people died as a result of the attack. The historian Sheldon Harris claims that 200,000 died. In addition to Chinese casualties, 1,700 Japanese in Chekiang were killed by their own biological weapons while attempting to unleash the biological agent, which indicates serious issues with distribution.
During the final months of World War II, Japan planned to use plague as a biological weapon against San Diego, California. The plan was scheduled to launch on September 22, 1945, but Japan surrendered five weeks earlier.
Prisoners and victims
Despite the facility’s location in Northern China, great pains were taken by organizers of the facility that its inmates represented a wide array of ethnicities. Most of the prisoners of war were American.
Robert Peaty (1903–1989), a British Major in the Royal Army Ordnance Corps, was the senior ranking allied officer. During this time, he kept a secret diary. A copy of his entire diary exists in the NARA archives. An extract of the diary is available at the UK National Archives at Kew. He was interviewed by the Imperial War Museum in 1981, and the audio recording tape reels are in the IWM’s archives.
Death toll estimates from the deadly pathogens released under Ishii’s orders, which caused epidemics, range from 200,000 to 580,000; most of the dead were Chinese. Estimates of the total number of men, women, children, and infants who were tortured and slaughtered at Unit 731 are between 3000 and 12,000. Nearly 30% of those who died at Unit 731 were captured Soviet soldiers. Other unfortunates included Southeast Asians and Pacific Islanders. It’s estimated that close to 200 American and British allies also perished at the death camp.
On August 15, 1945, Japanese Emperor Hirohito surrendered unconditionally, which ended Japan’s involvement in World War II as well as the war with the Chinese. Immediately after surrender, the Japanese demolished Unit 731 in order to erase all evidence and memory of the atrocities committed at the despicable death camp. Ishii ordered the remaining 150 subjects to be executed. Bodies and body parts were buried. Inexplicably, as the camp was being demolished, the Japanese released thousands of plague-infested rats into the surrounding provinces. In addition, the Japanese released millions upon millions of plague-infested fleas into the area. As a result, an additional 20,000 to 30,000 Chinese died from plague and other diseases over the following 3 years.
Immunity from US and the West
Realizing he would be prosecuted for war crimes, Dr. Ishii faked his own death and went into hiding to evade justice. He was found in 1946 and turned over to American occupation forces for interrogation. The US was desperate not to have Ishii’s knowledge of biological weapons fall into the hands of Russia, including the results of his myriad medical experiments on humans. The US also wanted to supplement its own germ warfare program knowledge base with the results of the biological warfare experiments conducted at Unit 731.
Initially, the US and Japanese governments denied that atrocities had occurred but a body of official information was made public. A file from General Douglas MacArthur’s headquarters states that the investigation of Unit 731 was “under direct Joint Chiefs of Staff order…….the utmost secrecy is essential in order to protect the interests of the United States and to guard against embarrassment.” Finally, in 1993, US Defence Secretary William Perry promised to declassify record of WWII biological experiments so as to calm down the intense public pressure.
Other recently released documents show the U.S. spared Ishii and his “scientists” from war crimes trials in exchange for the horrific data they’d collected. Following imminent defeat in 1945, Japan blew up the Unity 731 complex and Ishii ordered all the remaining “logs” to be executed. Not soon after, Ishii was arrested. Then, the respected General Douglas McArthur allegedly struck a deal with Ishii. If the U.S. granted Ishii immunity from his crimes, he must exchange all germ warfare data based on human experimentation. So Ishii got away with his crimes because the U.S. became interested in the results of his research.
While not directly responsible for these acts, the actions of the American government certainly illustrated that it was more than willing to condone human torture for advancements in biological warfare that could kill even more people.
In 2000, the U.S. Congress passed the Japanese Imperial Government Disclosure Act requiring that all Japanese documents seized by the U.S. Army be released. But these records, currently kept by the National Archives, have yet to see the light of day.
“By virtue, ostensibly, of their cooperation with their American conquerors, the former leadership of Unit 731 lived relatively quietly and undisturbed in the postwar period. The freedom they enjoyed stands in stark contrast to the fates of other, better known, ‘Class A’ war criminals,” writes Unit 731: Testimony author Hal Gold. [Of course, there was also immunity for the scientists and doctors under Project Paperclip where the US brought over 1800 German war criminals and their families to secretly work for the US government.
Watch full playlist below: