National Affairs: Secret Lost

The Pearl Harbor Committee blithely tossed away one still-secret U.S. weapon. George Marshall’s letters to Governor Dewey (see above) mentioned that the U.S., with the help of the British, had decoded German as well as Japanese messages. George Marshall begged the Committee to cut out these references. The Committee refused.

Publication of the letters thus gave the Germans their first knowledge that their code had been broken. It was also a breach of diplomatic confidence with the British, who had let the U.S. in on the secret on the understanding that it would be kept.