In terms of military intelligence, bitter rivalries hampered effective cooperation between the army and the navy. Despite its still limited, peacetime size and constrained budget, the army's code-breaking team, headed by William F. Friedman and Frank B. Rowlett, in the Signal Intelligence Service achieved a startling success in September 1940 in breaking the Japanese "Purple" cipher, Tokyo's main new diplomatic code. The navy had established its cryptographic unit, OP-20-G later than the army and suffered comparative lack of experience. Perhaps in compensation, the navy’s unit was expanded to 147 members by 1940, several times the size of the army's. Under a joint agreement, the two services worked together on deciphering the Japanese diplomatic code. But inter-service rivalry prevented them from cooperatively exploiting the army's breakthrough enabling the reading (code named MAGIC) of the Japanese diplomatic code. Instead, they settled on an otherwise incomprehensible arrangement by which the army worked on decoding Japanese diplomatic messages sent on even dates and the navy on those bearing odd dates. The two services took turns on alternative months delivering the decoded intercepts to the president. Such rivalry would continue throughout the war, hampering U.S. intelligence assessments and also complicating co-operation between the American and British intelligence service.
Wednesday, November 3, 2010
This is from a National Park Service history of the OSS, describing the situation in US military intelligence at the beginning World War II: