In World War II, Japan created a top-secret project named Unit 731. Officially called the Epidemic Prevention and Water Purification Department of the Kwantung Army, Unit 731 carried out human experiments on unwilling subjects.
Japan committed many horrors throughout WWII, but arguably the most gruesome acts occurred in Unit 731. Located in the Pingfang district of what is now China, most of the test subjects for Unit 731 were Chinese.
By the end of WWII, as surrender became imminent, the Japanese involved with Unit 731 attempted to destroy all evidence of the acts they committed. Unlike their German counterparts, the scientists running Unit 731 were never punished for their human experimentation. It would be many years before witnesses started speaking out about the unit, and only now does the public understand what really went on there.
In order to investigate the internal effects of a newly developed injection, Unit 731 performed live dissections on thousands of test subjects without the use of anesthetic. None of the victims survived.
Scholars and former unit members estimate that about 3,000 people perished in this and other medical experiments performed by Unit 731.
The unit studied anthrax, cholera, and other pathogens by infecting victims. One such experimentation was with the bubonic plague, which the Japanese exploited using infected fleas and various delivery systems.
The weapons they developed were used to infect Chinese cities, with varying degrees of effectiveness.
Victims' limbs were sometimes removed in order for doctors to observe the range of effects and "learn the limits of the human body." Severed limbs were at times reattached to other parts of the person's body.
As in the other experiments, all subjects were alive and no anesthetic was used.
To test the effects of intense pressure on the human body, Unit 731 would lock people into large pressure chambers. Pressure would gradually increase until the subject perished.