Operation Bodyguard

Before the Normandy landings, the allied forces implented a massive plan of deception aimed at confusing the enemy as to the size and locatin of the actual invasion.

It was aptly named such after a famous Churchill quote from 1943 -

The main operation consisted of several Sub-operations which where
Operation Fortitude North and South - Designed to make the Germans believe invasion would be through Norway,
operation Zeppelin - Deisnged to make the germans believe that landings would take place in Crete and Romania.

The deceptions involved massive Propaganda trickery and out right amateur dramatics, with stories of a pretend american unit being backed up by fake battalions with fake tanks setting up camp at dover.