Unit 731 was a covert biological and chemical warfare research and development unit of the Japanese army during World War II. To discover the effects of different biological and chemical weapons, as well as other less well-known diseases at the time, Unit 731 performed lethal experiments on different (mostly white) prisoners of war. The experiments ranged from simple medical interventions to truly evil and sadistic actions against prisoners.
The origin of Unit 731 begins with a man named Shiro Ishii, and I think we should give a slight bit of background on him. Ishii was born in Shibayama in 1892. During his university years, he studied medicine at Kyoto Imperial University. Then, in 1921 he was commissioned into the Imperial Japanese Army as a military surgeon. For you military nuts out there, his rank was a surgeon lieutenant. I believe the Japanese forces have separate military ranks for medical personnel.
A year after being commissioned, Ishii was assigned to the 1st Army Hospital and Army Medical School in Tokyo. He impressed his superiors enough to gain postgraduate medical schooling at his previous university, Kyoto Imperial University. While studying his postgraduate education, Ishii would grow bacteria “pets” in Petri dishes, which made him known to the university staff, probably as the weird dude who walks his Petri dishes.
After his schooling, Ishii began to advocate for the creation of a Japanese bioweapons program. To further this goal, he began a two-year tour of the West in 1928 where he performed extensive research into the effects of biological warfare and chemical warfare. As many may know, Germany was pretty good at bioweapons as evidenced by their use in World War I. His research garnered him support from high-ranking officials, and it was in 1935 that Ishii was promoted to surgeon lieutenant-colonel and awarded formal control over Unit 731 a year later.
Now, a good question to ask at this point is: what was the point of Unit 731? Well, since Ishii garnered so much high-level support, Unit 731 was created to be the biological and chemical warfare research hub for all of Japan. This is where Japan would develop its deadliest weapons. And with the development of biological and chemical weapons also comes the testing of those weapons. Thus, Unit 731, along with smaller unit attachments, was set up to perform these tests and was hidden under the moniker: the Epidemic Prevention and Water Purification Department.
The formation of Unit 731 began with the forced eviction of the residents of eight Chinese villages to make way for the headquarters. At this point, the Japanese Army already occupied a large portion of China. With the displaced population, as we’ll see, also came a number of homeless people on which Unit 731 would be able to test. Along with the homeless, criminals, ex-pat citizens, prisoners of war, and children would also be among the test subjects.
Because this article is a Halloween article, I think we’ll deep dive into the atrocities committed. Please be warned that some of the next sections are truly awful things to hear. Please consider this your trigger warning, and that is for all triggers. So, if you know that you are not one to do well with disturbing details, please read another article; possibly our more lighthearted Emu War article.
Firstly, since Unit 731 was developed to assist with the creation of Japan’s biological weapons, we’ll begin with those. There are a lot of accounts of what happened in Unit 731. Some come from diaries written by POWs while in captivity, some come from former Unit 731 medical employees. These testimonies are often backed up by different documents from the time. For instance, a certain high-level military official may have visited Unit 731 at a certain time, and one of the POWs would have noted this in his diary. But as for proper documentation, there is none. All incriminating evidence was destroyed, which we will touch on in a moment.
Although the accounts are debated, for this article, we will make the claim now that the biological experiments to follow did occur.
The biological experiments had two components. First, it was what I’ll refer to as the small-scale testing, and then the large-scale testing. For the small-scale testing, I’ll describe part of the experience of Major Peaty, a British Army officer and POW held at Unit 731.
Major Peaty was held at Unit 731 for, I believe, between 1-2 years. Within this time, he recorded many experiments being done on those in his company. However, those experiments are arguably the least intense that we’ll discuss today. Firstly, all of the men, who were white, were consistently injected with usually unknown substances. At first, these vaccines generally caused no issues. The men are described as being somewhat jovial when waiting for the vaccinations. They would joke with each other and generally have a good time. However, things began to take a turn when the men started to develop serious, constant diarrhoea. Over the course of a few months, this diarrhoea steadily got worse and worse. Men began dying daily, literally shitting themselves to death, and that’s not funny, I’m being serious.
The men, who were unknowingly being injected with deadly diseases, would request medical assistance from the Unit 731 doctors. Because, up to this point, they had been treated relatively well for POWs. They had a large amount of food provided, and they were generally kept quite healthy, but this began to change. When the men asked for assistance from the doctors, they were taken to a field and were forced to play baseball. Or they were forced to sprint for long periods. If a man did not soil himself, he was said to be lying and sent away with no help from the doctors.
The doctors eventually began examining the men. To do so, they would insert a glass rod into the mens’ anuses to inspect their colon. Although, they would never provide medicine. The men were then asked questions to test their mental capacity, then sent back to the holding cells to eventually die.
Many men died during this experiment and the numbers are debated, but it was likely to be over 1,000. Major Peaty, however, survived and did find his way back to England to be with his family. This is only one form of biological experimentation performed by Unit 731, but some of the more heinous experiments will be discussed in a moment. Further tests in this small-scale capacity also included testing prisoners with bubonic plague, cholera, smallpox, botulism, and other diseases.
Now, I mentioned that there was also large-scale biological warfare testing. As Unit 731 was positioned in China, it was a perfect staging area for the Japanese to test biological warfare. To do this, the Unit bred plague-infected fleas. These fleas were then spread by low-flying aeroplanes on Chinese cities. This ended up killing tens of thousands of people with epidemics of the bubonic plague.
Unit 731 had also planned to use plague as a biological weapon against San Diego, California during World War II. This attack was planned to occur five weeks after the Japanese had surrendered. Through the use of plague fleas, infected clothing supplies and other infected materials, the Unit caused large-scale outbreaks of cholera, anthrax and plague, which were estimated to have killed at least 400,000 Chinese civilians.
Unit 731 was not only concerned with biological and chemical warfare, they also used prisoners in the testing of certain weapons. Human targets were used to test grenades. To do so, the prisoners were positioned at various distances and in various positions. Prisoners were also used to test flamethrowers. The prisoners were also tied to stakes and used as targets for pathogen-releasing bombs, chemical weapons and explosive bombs. While still tied to the stakes, they were also used to test bayonets and knives.
Further testing and experimentation got much more sadistic. Along with depriving subjects of food and water to determine the length of time until they died, they were also placed in low-pressure chambers until their eyes popped from their sockets. There were experiments on the relationship between temperature, burns and to what extent humans could survive. Prisoners were placed in centrifuges and spun until death. They were injected with animal blood and seawater, exposed to lethal doses of x-rays, sent to gas chambers, and burned or buried alive and electrocuted.
One area the Unit devoted a large amount of time to was that of frostbite. The tests they would perform would sometimes involve taking captives outside, dipping different extremities into water, and allowing them to freeze. To determine if the limb was frozen, the extremity would be struck with a short stick until it emitted a sound similar to striking a board. Ice would then be chipped away and the area would be doused with water, or the limb would be brought close to a fire. To determine if any area was still frozen, the prisoner would be bludgeoned.
One Japanese Army major is quoted as saying the following of the frostbite experiments: “The technician placed the women’s hands into a freezing apparatus and lowered its temperature to minus ten degrees Celsius, then slowly reduced the temperature to minus seventy degrees. The condition of the frostbite was then studied. The result of the test was that the flesh fell from the women’s hands, and the bones were exposed. One of the women had given birth in prison, and the baby was also used in a frostbite test. A little later, I went to look into the women’s cells and they were all empty. I assume that they died.”
The most sickening part of this experimentation is that the research data received still forms our treatments of frostbite to this day.
I mentioned a moment ago that we would come back to some of the biological research. One area that is particularly awful was that of syphilis. In the beginning, certain prisoners were injected with syphilis and then studied to see its effects on the body. However, one prison guard said the following about the method:
"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 (also sometimes male and male), 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."
Some children grew up inside Unit 731 also infected with syphilis. They would also be examined to determine the effects the disease had on the body in different stages.
Rape and Forced Pregnancy
Please note that the next bit of information has to do with sexual assault. Female prisoners of Unit 731 were subjected to rape and forced pregnancy. The reason for this torture was so that the unit could study the transmission of diseases from mother to child, particularly syphilis. There are no reports of children surviving Unit 731. It is suspected that the children or female prisoners were killed after birth or aborted.
In a very graphic bit of detail, a guard described how the female prisoners, while also being experimented on, were also subjected to sex crimes. The guard stated (I’m going to paraphrase slightly here):
“One of the former researchers...told me that...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 [showed signs of syphilis]. He gave up the idea, left and locked the door, then later went on to his experimental work."
Finally, one of the worst bits of experimentation was vivisection. For those of you that do not know what vivisection is, it helps to break down the word. Vivi, which comes from the Latin vivus meaning ‘alive’, and sectio ‘cutting’. This refers to the cutting of a living organism, and in this case, the organism was humans. Thousands of men, women, children and infants imprisoned at the camp were subjected to vivisection, without anesthesia. Vivisections were performed on people infected by various diseases, with the researchers removing organs to study the effects of disease on the body.
A 72-year-old former medical assistant at Unit 731 said the following during an interview in the 1990s: “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. 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 he finally stopped.”
No anesthesia was used during these vivisections because it could likely taint the results of the experiments, as it was claimed by Unit 731 researchers.
Prisoners also had limbs removed to study blood loss. Some prisoners were cut open and their stomachs removed, with their esophagus attached directly to their colon. Researchers would remove portions of different organs, including the spleen, liver, kidneys, lungs and brain. Similar experiments were also performed on infants, but I refuse to go into detail on anything to do with that.
It has been claimed that with all of Unit 731’s experiments included, just over half a million people were killed. This includes those killed in large-scale biological warfare experiments.
Once the war began to die down, you can imagine that Japan probably wouldn’t want this information seeing the light of day. So, as I mentioned earlier, all incriminating documents were destroyed. Further to this, 600 Chinese and Manchurian labourers were shot. Ishii ordered all members of Unit 731 to disappear and “take the secret to the grave”. The members were also given potassium cyanide vials in case they were captured.
Obviously, this information did get out. You would expect that the world, at least the Americans and other major powers would be furious about this. Surprisingly, the Soviets were very aggressive with their reaction, although not publicly. They held trials for twelve top military leaders and scientists from Unit 731. The head prosecuting attorney of these trials was Lev Smirnov, who had been one of the top Soviet prosecutors at the Nuremberg Trials. The doctors and army commanders who had perpetrated the experiments received sentences from the court ranging from two to 25 years in a Siberian labour camp.
America did something entirely. Instead of charging the members of the Unit, General Douglas MacArthur offered the Unit 731 physicians, including Ishii, immunity in exchange for their research on biological warfare and the data from human experimentation. The immunity was only offered if they shared the information with America and no other nation. America felt the information was valuable and did not want other nations, like the Soviet Union, to gain the biological weapon information. America did monitor the activities of unit members, which included reading and censoring their mail.
Ishii was himself granted war crime immunity for the provision of the information. However, from 1948 to 1958, less than 5% of the documents were transferred onto microfilm and stored in the National Archives of the United States, before they were then shipped back to Japan. Which left a pretty big discrepancy of information.
Response from the Japanese government is not very forthcoming. History textbooks contain references to Unit 731, but since there are no legitimately explicit documents proving its existence, the government has not formally acknowledged it.
Unit 731 leader, Shiro Ishii, went on living his life in Tokyo. He died on 9 Oct 1959 from laryngeal cancer at the age of 67, which is unbelievably more than the man deserved. According to his daughter, he converted to Catholicism shortly before his death, so make of that what you will.
I could not think of anything else to call this article other than “the Atrocities of Unit 731” because that’s all there was to it. This experimentation was nowhere near worth the cost. The acts committed by Ishii and his depraved researchers were nothing short of disgusting. We live in a world that is full of evil and true villains. This is a story about evil and true villains. These men subjected not just men and women, but also children, the most vulnerable and innocent of any society, to unimaginable pain and torture for the sake of medical research. Which, in the end, was found to be worth nothing, and that is truly unfortunate.
"The Devil's Doctors: Japanese Human Experiments on Allied Prisoners of War" by Mark Felton