Description:
On December 3, 1941, officers of the U.S. Army Signal Intelligence Unit decoded a message sent from Tokyo to the Japanese embassy in Washington, ordering embassy staff to destroy its code books and other sensitive material. This, the officers determined, meant that Japan was preparing to break off diplomatic relations with the United States and go to war. When, they could not say; to gain a precise date, they would have had to break the Japanese naval codes. Therein, writes Stephen Budiansky in Battle of Wits, lay the rub: "Since mid-1939, America had not read a single message in the main Japanese naval code on the same day it had been sent. For most of the period from June 1, 1939, to December 7, 1941, the [U.S.] Navy was working on naval messages that were months, or even over a year old." For all their lack of preparedness and occasional inefficiencies, and for all the disdain with which some Allied ground commanders held the work of military intelligence, writes Budiansky, Allied cryptographers were of critical importance in determining the outcome of World War II. The decoding of Japanese and German encryption engines, for instance, helped the Allied navies gain victory in the battles of the Atlantic and Midway, while the translation of secret German railroad schedules allowed Winston Churchill to warn Josef Stalin that the German army was about to invade the Soviet Union--though Stalin refused to take the warning seriously. The codebreakers, in short, "averted disasters that would have been terrible setbacks to the Allied cause," and they almost certainly saved a considerable number of lives as they labored to crack such profound puzzles as Enigma and Purple. Budiansky's narrative is strong on the science of cryptography--so much so that readers without a background in mathematics and logic may have trouble following the arcana of key squares, bigrams, and all the other trade secrets of cryptanalysis. Readers willing to brave matters technical, however, will find Budiansky's comprehensive account to be the best single book on the subject, and one well worth their attention. --Gregory McNamee
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