During the Sino-Japanese War ( 1937 – 1945 ) , Unit 731 of the Imperial Japanese Army conducted human experimentation on thousands , mostly Chinese . In military campaigns , the Japanese army used biological weapons on Chinese soldiers and civilians . Plague fleas , infected clothing , and infected supplies encased in bombs were dropped on various targets . The resulting cholera , anthrax , and plague were estimated to have killed around 400,000 Chinese civilians
Unit 731
Unit 731
Pandemic