ABSTRACT
Yet the 1945-1946 Congressional investigation into the Pearl Harbor disaster dealt intensively and extensively with the American solution of Japanese diplomatic codes before the attack and, to a lesser degree, with wartime military solutions.8 So the official histories referred to these, though sometimes obliquely. In addition, shortly after the war newspaper and magazine articles and books appeared dealing with the effects of American cryptanalyses-the victory at Midway in 1942 and the midair assassination of Admiral Isoroku Yamamoto in 1943, to name the most striking.9 e official histories relate these, though usually not with great specificity about the cryptanalyses. But about Allied solution of German cryptosystems-nothing, with one exception. In a secret 1944 letter published in the Congressional hearings, U.S. Army Chief of Staff General George C. Marshall, urging Republican presidential candidate omas E. Dewey not to make a campaign issue of pre-Pearl Harbor codebreaking, revealed with startling particularity the value of Allied cryptanalyses of both Japanese and German messages.10 ough the press picked this up,11 and knew about the import of codebreaking in the Pacific, no one-not the press, not Allied or former Axis popular or scholarly historians, not the official historians-followed through to the scope or impact of codebreaking in the European theater.
