The operation combined land, sea and air and began the liberation of France and later western Europe.
The D-Day landings set the wheels in motion for Allied victory on the Western Front.
As well as those from the UK, D-day forces included sailors, soldiers, and airmen from the USA, Canada, Australia, Belgium, Czechoslovakia, France, Greece, the Netherlands, New Zealand, Norway, Poland and others.
The invasion was delayed by bad weather.
Troops and supplies had been ready in May, but bad weather delayed the launch. Storms still caused havoc during the landings
Due to the stormy weather, only two of the 29 amphibious tanks made it to land under their own steam.
Storms also caused many regiments to land far from their intended points.
In total five sections of the beach were involved, across the Normandy coast.
West to East these were codenamed Utah, Omaha, Gold, Juno and Sword.
More than 156,000 Allied infantrymen stormed the five beaches, facing around 50,000 Germans troops.
By June 11 all five stretches of beach were secured, and work began on two temporary harbours.