In 1938 , the Japanese military secretly created North China Unit 1855 , a biological warfare unit based in Beijing , which operated laboratories next to the Temple of Heaven , Beihai and in the Union Hospital . Like Unit 731 , its more notorious counterpart , Unit 1855 devised virulent strains of bacteria and conducted lethal experiments on prisoners of war . Strains of infectious diseases developed by Unit 1855 were used about 70 times during the war , killing over 100,000 civilians in northern China . In 1943 , a strain of cholera released by the unit in southern Beijing to test its virulence killed 1,872 residents . Biological warfare was banned by the Geneva Protocol of 1925 . On August 15 , 1945 , immediately following the Japanese Emperor 's announcement of surrender , Unit 1855 began removing or destroying evidence of its existence and departed the city ten days later leaving few traces of its activities . The unit evaded the Japanese war crimes tribunals and remained largely unknown until later research by historians
Unit 731
Unit 731
History of Beijing