Allied air power also played an important part in the deception. In the months leading up to D-Day, Allied bombers attacked road and rail networks in an attempt to isolate the invasion area, but additional attacks were made on other parts of northern France to divert German attention away from Normandy.

In Operations ‘Taxable’ and ‘Glimmer’, the RAF dropped metal strips – codenamed ‘Window’ – along the French coast to confuse German radar. On the night of 5-6 June, as part of Operation ‘Titanic’, the RAF dropped dummy parachutists to simulate an airborne invasion and draw German forces away from key objectives.

The Allied deception strategy for D-Day was one of the most successful ever conceived. The Germans overestimated the strength of Allied forces in Britain, particularly in the south-east, and believed as late as July 1944 that a larger second invasion would land in the area around Calais. This helped the Allies achieve the key element of surprise and kept German reinforcements away from Normandy both on D-Day and in the weeks that followed.