Ten hours before the surprise attack on December 7, 1941, Americans intercepted a 14-part Japanese message.
They deciphered it at 4:37 A.M., Washington time, just hours before the attack, but the message remained in the code room; not until three hours later was it delivered to President Roosevelt.
By 11:00 A.M., the U.S. chief of naval operations and the army chief of staff received the deciphered message, which was then transmitted to all areas of the Pacific except Hawaii, where the receiver was not working.
The message did not reach Pearl Harbor until nearly three hours after the attack, which took 3,000 lives.