In 1944, the Castle also played a role in preparations for the Normandy invasion. A few weeks before D-Day, captured German Würzburg, Freya, and Seetakt radars (types used by the Germans defending the French coast), were moved to the Castle. There, they were used in the training of RAF bomber crews (including 617 Squadron, the famous "Dambusters") who were part of a massive effort to deceive the Germans as to the actual location of the Allied invasion. Beginning on the night before the D-day landings, thin strips of aluminum foil were to be dropped by the bombers near two locations far from Normandy. The strips were to be dropped in vast numbers, in carefully choreographed patterns, over many hours. It was hoped the bombers would thus be able to create on German radar an illusion of huge approaching naval fleets, even though the "fleets" were non-existent. The technique, perfected in the waters off Tantallon Castle, was carried out on the night of June 5–6 by the bomber crews in the waters off the coast of France.