Unit 731 and Unit 100 were the two biological warfare research centres set up in spite of the Geneva Protocol of 1925 banning biological and chemical warfare.
Led by Lieutenant-General Ishii Shiro, 3,000 Japanese researchers working at Unit 731’s headquarters in Harbin infected live human beings with diseases such as the plague and anthrax and then eviscerated them without anesthesia to see how the diseases infected human organs.
Because of the Unit’s secret nature, there is no complete list of the experiments that were undertaken by Unit 731.
Testimonies from participants shed some light about parts of the experiments. An anonymous medical assistant described in a 1995 New York Times interview his first vivisection:
“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 finally he stopped. This was all in a day’s work for the surgeons, but it really left an impression on me because it was my first time.”
But the Unit was not only infamous for its vivisections. Some prisoners sent to Unit 731 were taken outside and tied to stakes. The Japanese would then test new biological weapons such as plague cultures or bombs filled with plague-infested fleas on them.
Other studies involved exposing human guinea pigs, called ‘logs’ by the Japanese scientists, to their limits. Humans were locked inside pressure chambers to test how much the body could take before their eyes popped out.
Some human test subjects were taken outside during the harsh winter until their limbs froze off for the doctors to experiment how best to treat frostbite.
Since the Japanese army used poison gas during the war, one of the Unit 731’s mission was to develop a more potent poison gas, thus prisoners were subjected to poisoning.
In 1984, 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.
At least 3,000 people, not just Chinese but also Russians, Mongolians and Koreans, died from the experiments performed by Unit 731 between 1939 and 1945. No prisoner came out alive of the Unit’s gates.
During the war, the Japanese Imperial Army used biological weapons developed and manufactured by Unit 731’s laboratory in Harbin throughout China, killing or injuring an estimated 300,000 people.