Marching Orders: The Untold Story of How the American Breaking of the Japanese Secret Codes Led to the Defeat of Nazi Germany and Japan

by Bruce Lee

In the letter Marshall “begged the Governor to say nothing during the campaign” about the fact that U.S. government authorities had been reading Japanese codes and ciphers before the attack on Pearl Harbor. Not only was the information true, Marshall tells Dewey, “but much more important were the facts that (1) the war was still in progress; (2) the Japanese were still using certain of the pre-Pearl Harbor cryptosystems; and (3) the U.S. government was still reading highly secret Japanese messages in those systems, as well as highly secret messages of other enemy governments. Therefore, it was absolutely vital that Governor Dewey not use the top-secret information as political ammunition in his campaign.”