Shiro Ishii

Lieutenant General Shiro Ishii was head of the Japanese biological warfare program based at Unit 731 in Pingfan, China, during the Second Sino-Japanese War and World War Two in the Pacific. Ishii, who had presided over human experimentation perhaps on a greater extent than the Nazis, and waged biological warfare against the Chinese, was given protection by U.S. Army intelligence in exchange for data. Just the experimental parts of his program, much less the actual warfare, killed more human beings than the much better-known Nazi medical experiments.

He rose rapidly through the officer ranks, surprisingly since the medical branch was the least prestigious part of the Army. He had key patrons, such as then War Minister Sadao Araki, also leader of the Imperial Way Faction. Tetsuzan Nagata who in 1934 was the Army’s Chief of the Military Affairs Bureau, and the leader of the Control Faction, was extremely helpful to Ishii, extricating him from one of several brushes with the law.

Keiichi Tsuneini, a professor at Kanagawa University, found two significant documents from MacArthur's intelligence chief, Major General Charles Willoughby, dealing with the Japanese biological warfare research and operations by Unit 731. One, titled "report on bacteriological warfare" for the chief of staff of the Far Eastern Commission, dated July 17, 1947, The other, dated July 22,went to Major General SJ Chamberlin, director of intelligence of the US War Department General Staff, to illustrate the need for continued use of confidential funds without restrictions to obtain such intelligence.

Willoughby described the achievements of his unit's investigations, saying the "information procured will have the greatest value in future development of the US BW (bacteriological warfare) program". Citing a US War Department specialist in charge of the investigation, Willoughby wrote in the report that "data on human experiments may prove invaluable" and said the information was "only obtainable through the skilful, psychological approach to top-flight pathologists" involved in Unit 731 experiments.

Tsuneishi said it had been thought that the US had gathered the information high-handedly by making unit members choose between cooperating or facing war crime charges, "but it has become clear that this was done by winning (unit members') hearts with money and rewards". In 1947, SCAP G-2 tried to obtain the experimental data but "because war crime charges against the Unit 731 officers had been waived by then, the GHQ was apparently forced to offer monetary rewards to access the information."