On 6 June 1944, Allied forces stormed the beaches at Normandy. Alongside Operation Overlord - the invasion itself - the Allied command devised an elaborate two-part plan called Operation Fortitude. This plan aimed to draw enemy forces away from Normandy by inducing the Germans to believe that the main invasion of France would occur in the Pas de Calais.Historians analysing the Normandy invasion frequently heap praise on Fortitude, using phrases such as "unquestionably the greatest deception in military history." Many of these historians assume that the deception plan played a crucial role in the June 1944 assault. This book re-examines the sources, and suggests that other factors contributed as much, if not more, to the Allied victory in Normandy and, that Allied forces could have succeeded without the elaborate deception of Operation Fortitude. Moreover, the persistent tendency to exaggerate the operational effect of Fortitude on the German military performance at Normandy continues to draw attention away from other, technical-military reasons for the German failures there.