Unit 731 was a secret biological warfare program in remote Manchukuo run by a prominent medical graduate of Kyoto University named Ishii Shiro. Dr. Ishii recruited specialists from major japanese universities to conduct outrageous medical experiments on Chinese (and possibly some Allied) prisoners.

Many prisoners who were infected with disease-producing organisms (e.g.,anthrax, plague, gas gangrene, smallpox, and botulism) were killed before the disease ran its course and autopsied to document progress of the disease throughout the body.

At the end of the war,in exchange for immunity to prosecution for war crimes, Dr. Ishii shared the results of his experiments with the U.S.  biological warfare program and died a free man in 1959.