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National Museum of Nuclear Science & History

Unit 731

History Page Type:
Friday, May 4, 2018
Building on the site of Unit 731. Image courtesy of Wikimedia Commons.

By Avani Sihra

In the 1930s-‘40s, the Japanese Empire committed atrocities across Asia, such as the Rape of Nanking. German crimes such as human medical testing committed in concentration camps tend to receive more attention than Japan’s crimes against humanity, as more research has been done and more historians have spent time looking back and studying these horrific acts. However, the Japanese too played a part in human medical testing in a secret project called Unit 731.

Begun in 1937, Unit 731, located in Harbin, China, was created with legitimate intentions by the Japanese government. Started as an agency to promote public health, Unit 731 was meant to conduct research that would benefit Japanese soldiers, such as learning more about the ways in which the human body can withstand hunger and thirst and fight diseases. Early experiments were conducted on volunteers who had signed consent waivers, giving personnel permission. However, as the war intensified, they changed their methods.

Although the 1925 Geneva Accords had banned the use of biological or chemical weapons in warfare, the Japanese nevertheless wanted to prepare for these types of warfare. As these types of experiments were naturally ones that most people would not volunteer to take part in, the Japanese decided to use prisoners of war as their test subjects. Unit 731’s victims who were primarily Chinese and Russians, along with some Mongolians and Koreans.

The leader of the unit was Lieutenant General Shiro Ishii. Along with the other scientists he recruited, they experimented by infecting test subjects with different types of diseases to see how their bodies would respond to pathogens. As the Japanese destroyed most of the Unit’s records at the end of the war, little is known about the scientists who worked there.

Using the test subjects, the scientists injected different germs to see how they would react to one another in the human body, in an attempt to create new diseases. Referring to their victims as Maturas, or “wooden logs,” Japanese scientists would perform different types of procedures, such as vivisection, on live victims. Rats infected with the bubonic plague were released onto victims, with the intention of infecting the subjects so that they could be studied. Unit 731 was a place of torture that was, in the minds of many Unit 731 workers, a necessity in order to win the war.

Scientists in Unit 731 also experimented on their test subjects through pregnancy and rape. Male prisoners infected with syphilis would be told to rape female prisoners as well as male prisoners in order to see how syphilis spreads in the body. Women were involuntarily impregnated and then experiments were done on them to see how it affected the mother as well as the fetus. Sometimes the mother would be vivisected in order to see how the fetus was developing. 

Once it was clear that the Japanese were going to lose the war, unit workers destroyed much of the evidence of the experiments. Upon the formal surrender of the Japanese in August 1945, Unit 731 was officially terminated. The Japanese government did not admit to the wrongdoing committed by Unit 731 until very recently. The government did not acknowledge the atrocity until 1988, and even then, they did not apologize for what had happened. The project was highly secretive and much of the evidence had been destroyed; in addition, government officials who were aware of what happened in Unit 731 did not make their knowledge known to the public. Because of this lack of acknowledgment, the Chinese government took it upon themselves to spread awareness of the atrocities. In 1982, they established a museum in the same place where Unit 731 operated during the war.

Unlike some of the Nazi doctors who conducted experiments on prisoners and concentration camp inmates, none of those involved with the experiments at Unit 731 were ever punished for their crimes. Instead, after war’s end, many re-entered society and went on to have very successful careers in their fields. American forces, chiefly General Douglas MacArthur, decided not to put workers of Unit 731 on trial. MacArthur granted those involved immunity in exchange for the information they had gathered while doing their experiments. He believed that pursuing trials against these people would get in the way of the Americans receiving the medical information that had been documented from these experiments. Because of this decision, justice was never served.

More Historical Resources:

Frank, Richard B. Downfall. Penguin Books, 1994.

Kristof, Nicholas D. “Unmasking Horror -- A special report; Japan Confronting Gruesome War Atrocity.” New York Times, Accessed 3 May 2018.

Stockton, Richard. “Inside Unit 731, World War II Japan’s Sickening Human Experiments Program.” All That’s Interesting, Accessed 3 May 2018.

Unit 731. Unit 731: Japan’s Biological Warfare Project, Accessed 3 May 2018.