1944 D.day.

Under the overall umbrella of Operation Bodyguard, the Allies conducted several subsidiary operations designed to mislead the Germans as to the date and location of the Allied landings. Operation Fortitude included Fortitude North, a misinformation campaign using fake radio traffic to lead the Germans into expecting an attack on Norway, and Fortitude South, a major deception involving the creation of a fictitiousFirst United States Army Group under Lieutenant General George S. Patton, supposedly located in Kent and Sussex. Fortitude South was intended to deceive the Germans into believing that the main attack would take place at Calais.  Genuine radio messages from 21st Army Group were first routed to Kent via landline and then broadcast, to give Germans the impression that most of the Allied troops were stationed there. Patton was stationed in England until 6 July, thus continuing to deceive the Germans into believing a second attack would take place at Calais.

Many of the German radar stations on the French coast were destroyed in preparation for the landings. In addition, on the night before the invasion, a small group of Special Air Service (SAS) operators deployed dummy paratroopers over Le Havre and Isigny. These dummies led the Germans to believe that an additional airborne landing had occurred. On that same night, in Operation Taxable, No. 617 Squadron RAF dropped strips of "window", metal foil that caused a radar return which was mistakenly interpreted by German radar operators as a naval convoy near Le Havre. The illusion was bolstered by a group of small craft towing barrage balloons. A similar deception was undertaken near Boulogne-sur-Mer in the Pas de Calais area by No. 218 Squadron RAF in Operation Glimmer.