Enigma and the Codebreakers

Did the code-breakers and ULTRA help to win the war?

For many years after the war, the work of the code-breakers remained a secret. The ULTRA files were locked away.Today more is known about Enigma and ULTRA. Historians can study the effects they had on the course of the war. Codebreaking did not win the war, but it probably helped to shorten it - perhaps by a year or more. It also contributed to the success of many Allied campaigns from 1941 onwards.

North Africa, 1942
By breaking codes used by Rommel's forces, the Allies could attack his supply routes, helping to ensure Montgomery's victory in the Western Desert.

Battle of the Atlantic, 1940 - 1944
Until convoys were better protected by escort ships and aircraft, one of the only ways of fighting the U-boat threat was to use ULTRA to divert ships away from danger.

D-Day, 1944
ULTRA revealed the size and location of German forces in Normandy before the Allied landings began.

At other times ULTRA was not used effectively. It did not prevent the Allied setbacks at Arnhem and the Ardennes in north-west Europe during the last year of the war.

To prevent the Germans from suspecting that their codes were being broken, the Allies sometimes took no action even when they knew their enemy's plans.

The code-breakers legacy

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The code-breakers' legacy