retransmission to Berlin. Having both the original text and the Enigma-encoded intercept of it, the codebreakers had the best possible source material for a chosen-plaintext attack on the Germans' Enigma key. Operation Fortitude 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. In order to maintain his credibility, it was decided that Garbo (or one of his agents) should forewarn the Germans of the timing and some details of the actual invasion of Normandy, although sending it too late for them to take effective action. Special arrangements were made with the German radio operators to be listening to Garbo through the night of 5/6 June 1944, using the story that a sub-agent was about to arrive with important information. However, when the call was made at 3 AM, no reply was received from the German operators until 8 AM. This enabled Garbo to add more, genuine but now out-of-date, operational details to the message when finally received, and thus increase his standing with the Germans. Garbo told his German contacts that he was disgusted that his first message was missed, saying "I cannot accept excuses or negligence. Were it not for my ideals I would abandon the work." On 9 Junethree days after D-dayGarbo sent a message to German intelligence that was passed to Adolf Hitler and the (OKW; German High Command). Garbo said that he had conferred with his top agents and developed an order of battle showing 75 divisions in Britain; in reality, there were only about 50. Part of the "Fortitude" plan was to convince the Germans that a fictitious formationFirst U.S. Army Group, comprising 11 divisions (150,000 men), commanded by General George Pattonwas stationed in southeast Britain. The deception was supported by fake planes, inflatable tanks, and vans travelling about the area transmitting bogus radio chatter. Garbo's message pointed out that units from this formation had not participated in the