D-Day, the Allied invasion of Normandy on 6 June, 1944, was the largest amphibious assault every undertaken.
The offensive involved some 75,000 British, Canadian and other Commonwealth troops landing on beaches in northern France from 6.30am that day.
Bolstered by troops from the United States and fighters from the Free French, the total invasion force numbered more than 130,000 personnel.
The D-Day operation had actually begun hours earlier, just after midnight, as airborne troops were dropped behind enemy lines.
More than 7,000 ships and smaller vessels took part in the sea assault, supported by about 11,000 aircraft.
Five beaches were targeted for the invasion - and given the codenames Utah, Omaha, Gold, Juno and Sword.
Fourteen nations are credited with taking part in D-Day:
United States of America
How the day unfolded:
After more than a year of planning, poor weather actually delayed Operation Neptune - D-Day - by 24 hours.
A 50-mile stretch of Normandy coastline had been pinpointed, with five beaches assigned codenames:
Utah - US forces
Omaha - US forces
Gold - UK forces
Juno - Canadian forces
Sword - UK forces
Landings began at dawn - and the first men on the beaches were met with a brutal and sustained resistance from Nazi gun emplacements and pillboxes.
The beachheads had been mined and covered with obstacles such as huge metal tripods, wooden stakes and barbed wire.
By the end of the first day, more than 4,400 Allied soldiers had died, thousands more were missing.
German casualties are not known - but, again, estimates have suggested as many as 9,000 died within the first 24 hours.
Between D-Day and the end of Operation 'Neptune' on 30 June, the Allied navies landed over 850,000 men, 148,000 vehicles and 570,000 tons of stores on the beaches.
By the time the Battle of Normandy ended in August 1944, these numbers had increased to over 2 million men, 400,000 vehicles and 3 million tons of stores and supplies.
Did D-Day achieve its goals?
None of the targets were met on Day 1; the towns of Carentan, St Lo and Bayeux remained in enemy hands.
Only two beaches - Juno and Gold - were linked, and it wasn't until June 12 that all five were connected, in firm Allied hands.
But the landings did provide a permanent, hard-fought base of operations from which the Allies were able to push on through France, driving the Nazi forces back over the coming months and ultimately, defeat.