Double-Cross System - Operation Fortitude and D-Day Landings

Operation Fortitude and D-Day Landings

The British put their double-agent network to work in support of Operation Fortitude, a plan to deceive the Germans about the location of the invasion of France. Allowing one of the double agents to claim to have stolen documents describing the closely guarded invasion plans might have aroused suspicion. Instead, agents were allowed to report minutiae such as insignia on soldiers' uniforms and unit markings on vehicles. The observations in the south-central areas largely gave accurate information about the units located there: the actual invasion forces. Reports from southwest England indicated few troop sightings, when in reality many units were housed there. Reports from the southeast depicted the real and the notional Operation Quicksilver forces. Any military planner would know that to mount a massive invasion of Europe from England, Allied units had to be staged around the country, with those that would land first nearest to the invasion point. German intelligence used the agent reports to construct an order of battle for the Allied forces that placed the centre of gravity of the invasion force opposite Pas de Calais, the point on the French coast closest to England and therefore a likely invasion site. The deception was so effective that the Germans kept 15 reserve divisions near Calais even after the invasion had begun at Normandy, lest it prove to be a diversion from the main invasion at Calais.

The Allies were willing to risk exposing the Double Cross network to achieve the needed surprise for the Normandy invasion. However, early battle reports of insignia on Allied units that the German armies encountered only confirmed the information the double agents had sent, increasing the Germans' trust in their network. Some of the double agents were informed in radio messages from Germany after the invasion that they had been awarded the Iron Cross.