Unit 731: Inhumane Medical Experimentation During WWII

Unit 731, officially named the Epidemic Prevention and Water Purification Department of the Kwantung Army, began as a legitimate research facility in the city of Harbin. Its purpose was to improve public health and conduct research that might ultimately benefit Japanese soldiers. The unit's research subjects were Japanese soldiers who had volunteered and signed consent forms.

But that soon changed.

As many countries began shifting away from the use of chemical and biological weapons — the Geneva Convention, which established rules of war, had banned them to safeguard human rights — Unit 731's leader, microbiologist Shirō Ishii, saw an opportunity.

If such weapons were dangerous enough to ban, he reasoned, using them would give the Imperial Japanese Army a competitive edge in wartime. (Japan had signed the Geneva Convention but hadn't ratified it, leaving a loophole to slip through.)

So Ishii transformed Unit 731 into a covert biological warfare research center focused on developing and testing the very weapons that dozens of countries had agreed caused unnecessary suffering.

To get real-world test results when developing biological weapons, Unit 731 decided to use human guinea pigs.

No sane volunteer would expose themselves to such lethal bioweapons, of course, so Unit 731 began using unwilling human test subjects. To keep such experiments far from prying eyes, the facility relocated to Beiyinhe, outside of Harbin.

Kidnapping Test Subjects

Chinese prisoners of war were brought to Unit 731 to serve as human test subjects, and Chinese civilians were kidnapped off the streets in Manchuria and brought to the facility. Some people from bordering countries — Koreans, Russians, Mongolians — were captured too.

Torture and Medical Atrocities

Unit 731 became a barb-wired prison camp, where researchers deliberately infected their human subjects with pathogens like anthrax, botulism, cholera and bubonic plague. Victims then had their organs removed while they were still alive — without sedation or numbing agents — so the researchers could study the impact of various diseases.

Researchers infected some male prisoners with venereal disease like syphilis, then forced them to rape both male prisoners and female prisoners to spread the infection to them. The scientists would then study how the disease develops.

Women were raped and impregnated, and the pregnant women were then subjected to all manner of horrors. Researchers would expose them to pathogens, for example, or radiation. They would then slice the pregnant woman open so they could examine the effects on her fetus.

Unit 731 had become a veritable house of horrors, with test subjects writhing and screaming in pain as the researchers conducted experiments.

While many of the experiments at Unit 731 focused on biological agents, the scientists tested the other types of weapons and tactics too.

Some prisoners had their limbs amputated, then surgically reattached to other parts of their body. Others had their body parts crushed, deprived of blood circulation until gangrene formed, or frozen solid and then doused with scalding water or fire in an attempt to get the body part moving again.

Researchers fired at their test subjects with guns, or impaled them with swords or bayonets, then studied the wounds. They also experimented with starving and dehydrating prisoners. Even children were experimented on, with some being forced into gas chambers.

Unit 731 may have been hidden from the public, but it was hardly a facility gone rogue. Sheldon H. Harris, a historian who spent 25 years investigating Japan's medical atrocities, found that many professional people and members of the ruling classes were aware of the gruesome research happening at Unit 731.

The youngest brother to Hirohito (Prince Mikasa) and his uncle (Prince Higashikuni Naruhiko) visited biomedical research facilities.

Unit 731 was an extensive campus of 150 buildings, where staff conducted research on up to 600 human beings at a time. It employed 3,000 skilled professionals including physicians, pathologists and pharmacists, as well as engineers.

Directors of the labs at Unit 731 visited some of the country's best medical schools, including Kyoto Imperial University and Tokyo Imperial University, where they showed films and photos of their experiments on humans and recruited promising young physicians.

Ishii, who would come to be known as the "Mengele of the East," saw medical ethics as a hindrance to scientific knowledge that might help Japan win wars.

He told his colleagues that, rather than healing or preventing disease, "the research we are now about to embark on is the complete opposite of these principles and may cause us some anguish as doctors. We pursue this research for the double medical thrill; as a scientist … probing to discover the truth in natural science; and as a military person, to build a powerful military weapon against the enemy."

To that end, the Japanese researchers used language that dehumanized their victims, referring to their research subjects as marutas, or "wooden logs."

Years after World War II, one lab technician recalled managing to extract some blood from a test subject before death, saying, "For people in laboratory work, this is ecstasy, and one's calling to his profession … showing compassion for a person's death pains was of no value to me."

Social psychologist Grace Danquin Yang, who authored award-winning research on Unit 731, says the researchers found ways to resolve their cognitive dissonance, the discomfort we feel when our behavior doesn't line up with our values.

"The Unit 731 perpetrators clearly did not change their behavior of experimenting on victims; instead, they changed their belief, at least nominally, so they could assure themselves that their mistreatment of prisoners was not morally wrong," she says.

Shirō Ishii might have helped shape Unit 731 into what it became, but he wasn't operating in a vacuum. By the late 1920s, a right-wing agenda was taking hold within The Imperial Japanese Army and Navy, driven by mid-level military officers.

"A conservative estimate suggests that in 1941, there were between 800 and 900 fanatical, emperor-worshipping secret societies within the Japanese Armed Forces," Harris says.

Nationalism, coupled with racism and xenophobia, was on the rise. The belief that the Japanese people were genetically and culturally superior to other Asian peoples was prevalent. This mindset swept through not just Japan's military but also within the Japanese government, including its national legislature, the Diet.

It was within this climate that Ishii was able to move forward with his plans to test biological weapons on human beings. Harris says:

Toward the end of World War II, the Soviets declared war on Japan. As their troops advanced into the country, Unit 731 shut down operations.

No human subjects survived the unit. Any test subjects who were still living when the Soviets invaded were killed, and the Japanese dynamited the facility to destroy evidence of their war crimes.

Unit 731, while notorious, wasn't the only such facility run by the Japanese at that time. It's believed that between 10,000 and 12,000 people — men, women, children, and infants — were killed in various Japanese research facilities.

Following the war, there was almost no accountability for Japan's atrocities at Unit 731. While the U.S. helped to bring to trial Nazi doctors who had also conducted medical experiments on human beings, it made no such effort to punish Shirō Ishii and his fellow researchers.

Instead, the U.S. granted them immunity from prosecution in exchange for access to their research. (Part of the motivation was to prevent Japan from sharing its research data with the Soviets instead.)

Japanese military officers were tried for crimes against humanity at The International Military Tribunal for the Far East, also known as the Tokyo Trial, but Unit 731's crimes weren't addressed. The Soviets did put a dozen medical staff from Unit 731 on trial for crimes against humanity, but they received relatively light sentences.

Ishii briefly went into hiding, even faking his death, but ultimately reemerged and enjoyed a successful medical career. Many of his fellow researchers from Unit 731 also had prominent, successful careers. Many showed no remorse for the suffering they caused, although one regretful former staffer (who was not directly involved in the research) has spoken out.

Japan ultimately signed the Geneva Convention and, in 2018, released the names of those who were involved in human experimentation at Unit 731.

Japanese leaders have also apologized for the atrocities committed, although many in China and elsewhere feel the apologies have fallen short. There have been additional calls for the U.S. to apologize for its complicity in the research.

The International Covenant on Civil and Political Rights, which states that "no one shall be subjected without his free consent to medical or scientific experimentation," has been signed by many countries, including Japan and the U.S.

Nearly a century after Unit 731 opened, Japan is still reckoning with this dark chapter of its history. Students' textbooks didn't mention the research at Unit 731 and other facilities until the 1990s — and even then, it was only after a legal battle that made it to Japan's Supreme Court.