Unit 731, a covert biological and chemical warfare research facility that operated during World War II in Japan, holds a chilling place in history. Veiled in secrecy and shrouded in denial for decades, this clandestine unit conducted gruesome experiments on human subjects, inflicting unimaginable suffering.
Unit 731’s existence is a dark chapter in a war so awful it already tests one’s faith in humanity. While we must not shy away from this disturbing truth, readers should be warned that some of the experiments detailed below are deeply disturbing. This is the shocking story of Unit 731, one of the most depraved groups in human history.
Who Were Unit 731?
Unit 731, short for the Manshu Detachment 731, was a covert biological and chemical welfare research unit of the Imperial Japanese Army during World War II. Its primary objective was to develop biological and chemical weapons by conducting heinous experiments on human subjects.
The reasoning behind the unit’s formation was chilling. The Japanese government believed that the banning of biological weapons by the Geneva Convention in 1925 proved their effectiveness. Even better, since so many countries had agreed not to use them, by developing their own, Japan could gain the upper hand.
While Unit 731 wasn’t officially founded until 1936, its work under the guise of the “Army Epidemic Prevention Research Laboratory” began in 1932. Japan had begun its occupation of Manchuria the previous year and the region gave Japan’s scientists access to more Chinese subjects for their experiments than they could have ever wished for.
Officially the unit’s purpose was to look into and prevent the spread of disease within the Japanese army but in reality, the unit’s real purpose was much more disturbing. The Japanese wished to use the Chinese, which they saw as “no-cost research subjects” so that they could lead the world in biological warfare.
Unit 731 was led by Lieutenant General Shiro Ishii and heavily backed by Colonel Chikahiko Koizumi, who later became Japan’s health minister. The group’s remit was simple: do whatever was necessary to make Japan the world leader in biological warfare. The Unit began by experimenting on the Chinese residents of Manchuria but as WW2 went on the Unit also began experimenting on prisoners of war.
In short, Unit 731 carried out some of the most heinous experiments imaginable. What started out as weapons research became murder and torture in the name of science. With next to no government oversight the unit’s scientists indulged their most macabre and sadistic curiosities. Readers are warned, disturbing content ahead.
Unit 731 vivisected thousands of men, women, and children while they were still alive, often without anesthesia. The subjects were infected with various diseases and then had their organs removed so that the effects of the diseases on the body could be seen.
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One member of the unit admitted in an interview to having vivisected a pregnant woman while another admitted to amputating subjects’ limbs to study the effects of blood loss. Other subjects had their stomachs removed and had their esophagus reattached to their intestines or had parts of vital organs removed to see how the body would cope.
When they weren’t cutting their victims open, the unit’s doctors were secretly carrying out biological warfare trials on the region’s occupants. For example, they experimented with using bubonic plague as a biological weapon by air-dropping plague-infected fleas (bred in Unit 731’s laboratories) across densely populated Chinese cities. The experiments killed tens of thousands.
Unit 741 also spread typhoid and paratyphoid germs into the wells of Nanjing city, causing a massive epidemic. In total at least 12 large-scale bioweapon field trials were carried out on at least 11 Chinese cities.
More conventional weapons were also tested on the Unit’s prisoners. Human targets were used to test the effectiveness of grenades at various distances and from different positions. Victims were often tied to stakes so that pathogen-releasing bombs, chemical weapons, and shrapnel bombs could be tested using different payloads.
Close-range weapons like flamethrowers, bayonets, and even knives were also tested on the Unit’s defenseless subjects.
Some of the most sadistic experiments, however, fell out of the remit of weapons testing. These tests were just used to see how far the human body could be pushed before giving out. The experiments often involved the subjects being tortured to death in the worst imaginable ways.
The examples are horrifying. In some tests, subjects were deprived of food and water to see how long it took for them to either starve or die of thirst. In other experiments, they were placed into low-pressure chambers to see how long it took for their eyes to pop from pressure.
Some experiments involved testing temperature extremes by either boiling prisoners alive or freezing them to death. The unit also tested how long the human body could survive upside down and how much weight it took to crush the average person to death. Some of the most inventive “experiments” involved placing subjects into massive centrifuges, injecting them with animal blood, and exposing them to lethal doses of X-rays.
Female prisoners often received the most horrific treatment. Unit 731 burnt through prisoners at an alarming rate, so female prisoners were often forced to become pregnant in order to provide more test subjects.
The unit primarily claimed its experiment on pregnant women was to test for the vertical transmission of certain diseases, especially syphilis. They were also interested in finding out how much damage a mother’s reproductive organs could take before fetal survival rates were affected.
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In reality, the experiments on women went much further. These female subjects were used for sex experiments and to test the effects of sex crimes on victims, rape after all is one of the oldest weapons of war.
A large number of children were born in captivity but there are no accounts of any survivors of Unit 731. It’s believed the children born during the unit’s experiments were either executed or used for yet more experiments before being disposed of.
The Cover Up
One might think Unit 731’s story ended with Japan’s surrender in 1945 but shockingly, there’s more yet to come. The full extent of the unit’s atrocities took decades to come to light.
Unit 731’s researchers can broadly be divided into two groups, those captured by the Soviets and those captured by the United States. The two groups met vastly different ends.
Those arrested by Soviet forces faced justice and were tried at the December 1949 Khabarovsk war crime trials. Unfortunately, before their capture the scientists destroyed much of the evidence, fearing what the Soviet soldiers would do to them if they discovered the truth.
The scientists arrested by the United States on the other hand were secretly given immunity in exchange for sharing the results of their experiments. The experiments were then covered up by the US and the perpetrators were paid off.
The US integrated the results of these horrific experiments into its own biological warfare program, similar to what it had done with Nazi scientists during operation paperclip.
The full truth of what had gone on only began to emerge in the 1980s when concrete evidence and testimonies from former members of the unit began to surface, shedding light on the scale of the atrocities committed. Throughout the 1990s, the truth gained wider recognition with the publication of books, documentaries, and the testimonies of survivors and researchers. This period marked a significant turning point in acknowledging and exposing the dark history of Unit 731.
For its part, Japan refused to acknowledge the unit’s existence until the 1990s by which time the cat was already out of the bag. In 1983 the Japanese Ministry of Education asked the historian Saburō Ienaga to remove references to the unit from one of his books. In 2018 the Japanese government finally released the names of 3,607 members of Unit 731.
Unit 731 stands as a chilling testament to the depths of human depravity. Emerging from the shadows of World War II, this covert unit’s horrific experiments on human subjects continue to shock and haunt us. The human cost is almost unimaginable.
Thankfully, the truth, once obscured by secrecy, gradually emerged, piercing the veil of denial. Unit 731’s existence serves as a stark reminder of the atrocities that can occur when ethical boundaries are abandoned in the pursuit of scientific advancement and military dominance.
Top Image: Unit 731 conduct a bacteriological test on a Chinese prisoner. Source: Unknown Author / Public Domain.
By Robbie Mitchell