David Kahn

The story of the Enigma machine begins in embarrassment on the German side, in luck on the British. Among the Germans, it rises from embarrassment through hubris before sinking back into chagrin; among the British from luck to luck to genius before ending in triumph. It is a story of ingenuity defeated by brilliance, of intransigence defeated by flexibility.

The Germans were embarrassed when British memoirs revealed in the 1920s that the Royal Navy had been reading their secret messages through nearly all of World War I. This had enabled it to bottle up the German High Seas Fleet in their North Sea ports and keep it from defeating Britain's Grand Fleet and so winning the war in an afternoon. The memoirs told them that the Russians had seized the main code book of the Kaiserliche Marine from the stranded cruiser the Magdeburg in 1914 and given it to the British. With this lucky break as their start, the British Admiralty's codebreaking establishment, called Room 40 from its first office, went on to solve other German naval codes and then German diplomatic systems, which culminated in the greatest intelligence feat of all time. This was the solution of the telegram of German Foreign Minister Arthur Zimmermnn to his minister in Mexico urging that country to war on America in return for the "reconquest" of Texas, Arizona, and New Mexico which, when disclosed to President Woodrow Wilson and made public by him, helped push America into World...