The Normandy Invasion signaled the beginning of the liberation of Europe from the grip of the Nazis in World War II, and the Allied offensive was aided by intelligence gathered by the codebreaking unit known as Ultra and by the use of the Germans' own Enigma code machine. Ultra was an umbrella code name given to the intelligence gathered by the use of the Enigma machine. Both the British MI-6 and the American OSS had uncovered many of Hitler's secrets through conventional intelligence and espionage channels, but there were two sources of secret intelligence that were unconventional. One was called Ultra and was derived from the interception and decryption of secret German wireless transmissions. Ultra made an important contribution to the end of World War II, and the name remained a classified secret until 1974 when former Group Captain F.W. Winterbotham of the Royal Air Force, who had been in charge of security and the dissemination of the information gleaned by Ultra, was allowed by British authorities to complete a memoir and mention Ultra for the first time. The name Ultra was used because it had once been the name of the old Admirals' code at Trafalgar, and it would now be used by the British and the Americans to refer to intelligence of the highest order derived from cryptanalysis. Ultra has been described by some as being the reason the Allies won the war, but this overstates the case. The Normandy invasion is a good example of the value of Ultra to the war effort, but it also shows that Ultra was not comprehensive and that it only provided part of the information needed by the Allies. The war was won not simply because the Allies had and depended on Ultra but because the Allies were well-prepared and strong.
A German U-boat was a key to the Allied success in World War II. In 1941, U-110 was captured off the coast of Greenland. It was standard operating procedure for a fleeing crew to set scuttling charges ins...