Operating under the cover of a Code and Cypher "School", Bletchley Park was in fact the center for British code-breaking in World War II. Originally a Victorian mansion, temporary structures at Bletchley Park housed 10, 000 people by 1945. It was here that the Ultra and Enigma codes were broken, providing the Allies with advance information on Axis maneuvers and attacks for the rest of the war. Despite a rather thin cover, the Germans never guessed what was going on at Bletchley Park. These operations remained top-secret for over thirty years, concealing the true reasons for many key Allied decisions.This account covers code-breaking operations and techniques, the role of mathematical genius Alan Turning, and the development of early computers as a by-product of cryptography.