I've heard a lot about the impact of Operation Fortitude, and read books on double agents and fake armies, but I dont recall reading about when the Germans realized they had been fooled. Did they ever truly realize this? What was the German situation by the time they released the troops in Calais? Did this come as a sudden realization or was it a conclusion they came to gradually? Did they realize they were duped or did they think the Allies just re-worked their plans since Normandy landings proved successful? Was it a fait accompli by the time they realized it?