Date

Dec 15, 1945

Description

The U.S. Navy sent an intelligence group -- a “technical mission”-- to do a wide-ranging investigation of a variety of topics, mainly involving naval technology but also the impact of the atomic bombings. Coordinated by Captain Clifton G. Grimes, Fleet Intelligence Officer in Charge of Intelligence for the Joint Intelligence Center, Pacific Oceans Area (JIC-POA), the technical mission to Japan had a staff of nearly 300 (including Japanese-Americans) who prepared dozens and dozens of reports based on captured documents and field work involving interviews/interrogations. The medical team led by Naval Reserve Captain Shields Warren, a Harvard pathologist, produced two reports on the atomic bombings, including this report, which contains the striking finding: “The atomic bomb is the most terrible agent of destruction known to man.” [45]

Illustrated with culturally insensitive graphs, the Navy report provided broad coverage of radiation exposure, including “secondary” or “residual radiation” and their effects. The report provided detailed information on the fallout problem, with a finding of “physiologically significant” levels of “residual radiation” in outlying areas after the bombings, including potentially dangerous levels in Nagasaki’s Nishiyama district. One of the data points was a reference [see page 45] to what became known in Japan as “black rain” – radioactive “droplets of yellow-brown liquid” that fell after the explosion.[46]

The official guidance given to the MED, Army, and Navy teams was to investigate but not to participate in treatment because that could have been seen as an admission of “moral responsibility.” In practice, however, the situation was complex: doctors for all three groups gave advice to their Japanese colleagues, sometimes provided medical supplies, and gave their evaluation of specific cases, which had implications for treatment regimens. This pattern continued during the work of the Atomic Bomb Casualty Commission.[47]

Like Stafford Warren, Shields Warren found the Siemes narrative compelling and presented it in its entirety. The report included first-hand accounts by various Japanese who had been in Hiroshima and Nagasaki at the time of the bombings. In addition, the report had the benefit of collaboration with Japanese university-based researchers, who provided maps and other information, such as estimates of blast pressure. The report also drew on interviews with scientists for a brief estimate of Japanese wartime nuclear physics research. One of them, Professor Masao Tsuzuki with Tokyo Imperial University (now University of Tokyo), had used rabbits in radiation effects research in the 1920s. Tsuzuki worked closely with members of the U.S. survey teams, but as has been noted he could be caustic. When Philip Morrison, with Los Alamos’ Weapons Physics Division, met Tsuzuki in Tokyo, the latter slapped him on the knee, saying, to the effect: “the Americans—they are wonderful. It has remained for them to conduct the human experiment.”[48]

Source

NARA, Record Group 38, Records of the Chief of Naval Operations, Naval Technical Mission to Japan, box 6.

Document published in following posting(s):

78th Anniversary of Hiroshima and Nagasaki Bombings: Revisiting the Record

Aug 7, 2023

Captain C[lifton] G. Grimes, Chief, Naval Technical Mission to Japan, to Chief of Naval Operations, “Target Report - Atomic Bombs, Nagasaki and Hiroshima Article I Medical Effects,” 15 December 1945, Top Secret [Enclosures (Maps) C, D, and G included]