government between the wars as a place to house its Codes and Cyphers School. It was occupied by that organization when World War II broke out in 1939. During the war, thousands of men and women worked in the house, all concerned with the breaking of codes and ciphers or in appraising and disseminating the information found by the codebreakers. The most important task for the group was the breaking of the Enigma code and decisions as to how to use the intelligence so discovered, and this process was called Ultra, or Top Secret Ultra. Most Secret Ultra was a term used to refer to things that were more secret than Most Secret, and this was changed to Top Secret Ultra when the Americans came into the war. The act of breaking Enigma ciphers was a significant part of the success of the Allies in the war, and while it is untrue to state that Ultra won the war or even a particular battle, it clearly made a big difference.
Ultra was created because of Enigma, and Enigma began after World War I when a Dutchman named Hugo Alexande
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