Built in Beiyinhe, outside of Harbin, Manchukuo during the Second Sino-Japanese War, the camp served as a center for human subject experimentation and could hold up to 1,000 prisoners at any given time.
"[3] Although protecting Japanese troops from disease was part of the agenda, the laboratory's primary objective was to develop an effective means to spread epidemics.
The subsequent occupation of Manchuria provided an environment conducive to Ishii's research as human test subjects "could be plucked from the streets like rats.
[3] The prison camp had three-metre-high (9.8 ft) earthen walls topped with electrified barbed wire and a moat with drawbridge surrounded the buildings within.
There were hundreds of rooms and smaller surrounding laboratories, office buildings, barracks and dining facilities, warehouses and munitions storage, crematoria, and the prison cells.
Some of the men soon died from exposure, hunger, cold, and the injuries from their experiments but several managed to survive, and spread word of the crimes against humanity being conducted by Shiro and his subordinates.
[7] Although the Kuomintang took no notice of these reports,[8] Zhongma Fortress was closed down due to the significant publicity, and its activities transferred to a new site closer to Harbin called Pingfang (Heibo), which came to be known as Unit 731.
[6] The graphic novel Maruta 454 (2010), by Paul-Yanic Laquerre, Song Yang and Pastor, depicts the escape of 12 Chinese prisoners from Unit Tōgō, based on Wang's testimony.