As commemorations are held in Normandy for the 67th anniversary of D-Day, an article from the BBC News website, first published for the 65th anniversary ceremonies, offers a brief reminder of the events and what the campaign was all about.
D-Day was the first day of the Allies' campaign to liberate Nazi-occupied north-west Europe. At the time, Operation Neptune, as the assault stage of the campaign was known, was the largest military operation ever attempted. It involved simultaneous landing of mainly US, British, and Canadian forces on five separate beachheads in Normandy, France.
More than a year in the planning, D-Day was originally intended to begin on 5 June, judged to be the most likely day to combine calm seas, a full moon and low water at first light.
But storms forced Supreme Allied Commander Gen Dwight Eisenhower to put it back 24 hours to start on 6 June.
Shortly after midnight, three airborne divisions - the US 82nd and 101st and the British 6th, numbering over 23,000 men - took off to secure the flanks of the beaches. En route were myriad naval vessels and landing craft. On their way to France they gave rendezvous in the Channel at 'Piccadilly Circus'. Thoughout the night positions on the invasion beaches were bombed, although many missed their target.