It was officially known as the . Originally set up under the "Kenpeitai" military police of the Empire of Japan, Unit 731 was taken over and commanded until the end of the war by General Shirō Ishii, a combat medic officer in the Kwantung Army. The facility itself was built in 1935 as a replacement for the Zhongma Fortress, and to expand the capabilities for Ishii and his team. The program received generous support from the Japanese government up to the end of the war in 1945. Unit 731 and the other units of the Epidemic Prevention and Water Purification Department were biological weapon production, testing, deployment and storage facilities. They routinely conducted tests on human beings (who were referred to internally as "logs"). Additionally, the biological weapons were tested in the field on cities and towns in China. Estimates of those killed by Unit 731 and its related programs range up to half a million people.