The two paragraphs near the bottom of the Washington Post’s July 13, 1956, editorial page were easy to miss. They celebrated the life of a man named Alfred T. McCormack who had just died of cancer at the age of 55. The anonymous writer wanted the public to know that during World War II, “commanders from the man in the White House down to the platoon leader stood in his debt, whether they knew it or not, for that rare and useful tool of war, knowledge of the enemy.” This was a tribute that precious few American intelligence officers ever received. Just who was Mc-Cormack, and what had he accomplished?
The backstory has “Magic” in it. That is what some called the work of a handful of brilliant codebreakers—mostly civilian mathematicians working for the U.S. Army—who, with few resources other than their own persistence and a little help from their counterparts in the U.S. Navy, broke Japanese diplomatic codes in the 1930s. It was an amazing achievement, one that made it possible for them to read secret traffic between Tokyo and Japan’s embassies overseas.
The codebreakers decrypted a few hundred messages a week, which then had to be translated from Japanese to English. Army and navy intelligence officers, who were not codebreakers but generalists, would then decide which messages were worth further processing—usually no more than 25 a day—and distribute them to a handful of senior-most officials, starting with the White House. Each official usually saw nothing but the translated message itself, without any analysis or even any notes, and could not keep a copy to peruse at leisure; he had to absorb the message’s significance on the fly and rely on his memory to compare it to earlier messages.
Both at the time and in retrospect, Magic was enormously important in the run-up to the surprise attack on Pearl Harbor on December 7, 1941. Most readers of the decrypted messages could see that Japan was preparing
