June 6th 1944, D-Day, codenamed "Operation Overlord" was the culmination of nearly two years of planning. It was the largest invasion force ever assembled. Over 6,800 ships, landing craft and other vessels were used to get over 130,000 men ashore onto the Normandy beaches. Meanwhile, overhead, nearly 25,000 men were dropped by glider and parachute, while bombers and fighters pounded the German defences. This programme uses remarkable archive film to tell the story of one of history's most momentous events and how the Allies conceived, developed and finally executed their audacious plan.