Peace Without Hiroshima: Secret Action At The Vatican In The Spring Of 1945
The author, under cover as a representative of the American motion picture industry, was a secret OSS agent who opened a secret channel of communication through the Vatican to the Japanese government in 1945. For many reasons, including the compartmentalization of American high strategic policy, this approach to possible peace was not effectively pursued, and the war ended with the atomic bombings. A fascinating account of a might-have-been.
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The periodic successes enjoyed by US cryptanalysts in breaking the Japanese PURPLE code could have made no contribution to advance warning of the Japanese attack, as PURPLE was used strictly for diplomatic, not military, communications. The attack was a deep shock to US intelligence, and "has taught the United States to gather more information and evaluate it better".

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