Ishii’s goal was always to find an effective biological weapon, so he investigated some of the most virulent diseases in human history. Many of his tests focused on the bubonic plague, which killed millions during the Middle Ages. He wanted to find ways to spread the plague quickly, which meant testing the best way to infect large numbers of people with the disease. Ishii ordered plague-infected fleas to be dropped from airplanes onto cities in China, leading to minor epidemics that killed thousands. In addition to fleas, Unit 731 dropped clothing or food infected with cholera and anthrax, leading to more epidemics and thousands of deaths.
But Unit 731 didn’t limit its research to just weaponizing disease, they also tested the effects of different injuries to the human body. Prisoners were often subjected to freezing temperatures to study the effects of frostbite, as guards beat them to determine how much feeling was left in their frozen limbs. The injuries were then left untreated to study the effects of gangrene, as the prisoner’s fingers or limbs began to rot and fall off. Other prisoners were subjected to experiments testing the effects of grenades from different ranges, and even flamethrowers. Obviously, few survived these types of tests.
Unit 731 was also very interested in venereal diseases, like syphilis or gonorrhea. Often, prisoners were infected with these diseases to test the effects and treatments. But these prisoners were also forced under threat of death to have sex with uninfected prisoners so that researchers could study how the diseases were transmitted from one person to another. They also wanted to study whether or not pregnant women could transmit a venereal disease to their fetus; thus women were sometimes forcibly impregnated for these tests.
Prisoners were also subjected to stranger experiments that reflect the callous disregard for human life shown by Unit 731. It was as though they simply wanted to satisfy their morbid curiosity. Prisoners were strapped into centrifuges that spun them at high speeds until they died. Others were injected with animal blood or seawater, simply to see how their body might respond. Still, others were bombarded with X-rays to study the effects of radiation. Some were simply buried alive or burnt to death. And others were denied food or water to see how long it took them to die.
Ultimately, Ishii’s experiments accomplished little. The Japanese never managed to develop a biological weapon that could turn the tide of the war. And Ishii’s attempts to pressure the Japanese military to use biological weapons in the Pacific were rebuffed several times. The only serious attack ever planned was to target the city of San Diego. However, this last desperate plan was aborted due to Japan’s surrender in 1945. After the surrender, Ishii was granted immunity by the American occupation forces in exchange for handing over his research. Ishii never stood trial for his crimes and lived out the rest of his days in Japan before dying of throat cancer years later. The fact that Ishii and other members of Unit 731 escaped prosecution truly rank among the worst failures of justice in history.