It was almost 30 years after the end of the Second World War before the war codebreakers of Bletchley Park were allowed to leave their cover, and tell what is now recognized as the greatest contribution to British single for the Allied victory . It was the obsessive, and instinctive caution of this kind that led to the almost miraculous preservation of Bletchley secret source of information throughout the war.

They were assisted by the unshakeable conviction that the German Enigma codes - several variants were used by all three armed services - has been impossible to break.

Ultra's contribution does not begin until the spring of 1941, as the Enigma cipher was progressively decoded. The effect was powerful, but not always decisive in the countryside north African fluctuating.

At the time of the Battle of El Alamein, the influence was less powerful than Ultra superiority decisive - 5 to 1 - in tanks and air power enjoyed by the Allies. The disappointment was at Bletchley that, given the constant flow of information being provided to Montgomery at the time, he was unable to cut off Rommel's retreat before it reaches Tunisia.

Its influence in the war against the U-boats - where naval Enigma was broken in the second half of 1941 - has helped provide information about U-boat locations to re-route the convoys to safety. It was calculated that approximately 1.5 tons of cargo were saved, and valuable time was bought to build new ships, and develop more effective anti-submarine defenses. (Thanks to docuwiki.net)