A Made Up Spy Network
Juan Pujol Garcia obliged the Abwehr, and invented a network of fictional sub-agents, whom he used as sources for more fabricated reports. The British, who frequently intercepted and decoded secret German messages, realized that somebody was hoaxing the Germans. When they discovered that it was Pujol Garcia acting on his own, they belatedly accepted his offer of services, and whisked him to Britain. There, he was given the codename GARBO, and directed to build up his imaginary network for the benefit of his German handlers. The original hoax was transformed into an elaborate double cross operation.
Through Pujol Garcia, the British carefully fed the Germans a massive amount of often true but useless information, mixed in with half-truths and falsities. The flood of reports from Pujol Garcia and his steadily growing network of fictional sub-agents transformed him, in German eyes, into their most successful spy in Britain. The moment to cash in on that trust came in the buildup to D-Day and the subsequent Normandy campaign. The ultimate aim was to convince the Germans that the Normandy landings were just the first in a series of planned invasions, with an even bigger one planned against the Pas de Calais.