Operation Fortitude Inflatable Tank
During World War II, British intelligence sought to deceive the Germans about the time and location of the intended invasion of Europe in 1944. So they devised Operation Bodyguard, which had three goals. First, conceal the time and date of the invasion. Second, convince the Germans that the main invasion would land in the Pas de Calais instead of Normandy. Third, convince the Germans, even after the Normandy landings, to maintain a strong defense in the Pas de Calais for at least two weeks, rather than drain it of defenders to reinforce their troops in Normandy.
A sub-plan, Operation Fortitude, created a fictitious First US Army Group in southeast England under the command of general George Patton. FUSAG sold its existence to the Germans with fake radio traffic between fictitious units, and by allowing German spy planes to fly over concentrations of FUSAG tanks and transports that were actually inflatable dummies.
German intelligence was also fed fake reports via double agents and turned spies about FUSAG’s intentions to invade the Pas de Calais, so as to tie down the German defenders there. A subsidiary, Fortitude North, created a fictitious British Fourth Army in Scotland, and convinced the Germans that it planned to invade Norway, so as to tie down the German divisions there.
Bodyguard convinced the Germans that the Normandy invasion of June, 1944, was not the main event, but the first in a series of landings. So they kept units guarding the Pas de Calais, threatened by the fictitious FUSAG, instead of sending them to reinforce Normandy. Bodyguard sought to convince the Germans to stay put in the Pas de Calais for two weeks after D-Day. Instead of two weeks, the Germans remained in the Pas de Calais for seven, before finally releasing the units there for use in Normandy. It was too late: by then, the Allies had been given precious time to build a powerful beachhead in Normandy, before breaking out to liberate France and Western Europe.