German coastal defences were stretched thin in 1944, as they prepared to defend all of the coast of northwest Europe. The Allies had already employed deception operations against the Germans, aided by the capture of all of the German agents in the United Kingdom and the systematic decryption of German Enigma communications. Once Normandy had been chosen as the site of the invasion, it was decided to attempt to deceive the Germans into thinking it was a diversion and that the true invasion was to be elsewhere.