The day the Allied forces invaded Normandy was called D-Day. On 6 June 1944, Allied troops landed on five beaches in Normandy, France, in the largest seaborne invasion in history.
The landings were the opening phase of Operation Overlord, the Allied plan to establish a foothold in Western Europe. The amphibious assault itself was codenamed Operation Neptune, while airborne troops landed inland before and during the beach assault. American forces landed at Utah and Omaha Beaches; British and Canadian forces landed at Gold, Juno, and Sword.
“D-Day” was not a unique nickname created only for Normandy. In military planning, “D-Day” means the day an operation begins, just as “H-Hour” means the specific hour. Normandy’s invasion became so famous that D-Day is now commonly associated with 6 June 1944. The date was delayed by one day because of poor weather, and Allied deception operations helped persuade Germany that the main attack might come elsewhere.