Operation Fortitude was the code name for a World War II military deception employed by the Allied nations as part of an overall deception strategy (code named Bodyguard) during the build-up to the 1944 Normandy landings. Fortitude was divided into two sub-plans, North and South, with the aim of misleading the German High Command as to the location of the invasion.

Both Fortitude plans involved the creation of phantom field armies (based in Edinburgh and the south of England) which threatened Norway (Fortitude North) and Pas de Calais (Fortitude South). The operation was intended to divert Axis attention away from Normandy and, after the invasion on 6 June 1944, to delay reinforcement by convincing the Germans that the landings were purely a diversionary attack.