As the German military grew in the late 1920s, it began looking for a better way to secure its communications. It found the answer in a new cryptographic machine called “Enigma.” The Germans believe the encryption generated by the machine to be unbreakable. With a theoretical number of ciphering possibilities of 3 x 10114 their belief was not unjustified. However, they never reached that theoretical level of security. Nor did they count on the cryptanalytic abilities of their adversaries. This publication provides a history of this cryptanalytic bombe.