In January 1944, the Germans told Pujol that they believed a large-scale invasion in Europe was imminent and asked to be kept informed. This invasion was Operation Overlord, and Pujol played a leading role in Operation Fortitude, the deception campaign to conceal Overlord. He sent over 500 radio messages between January 1944 and D-Day, at times more than twenty messages per day. During planning for the Normandy beach invasion, the Allies decided that it was vitally important that the German leaders be misled into believing that the landing would happen at the Strait of Dover.