In December 1943 President Roosevelt appointed General Eisenhower, as Supreme Allied Commander, with orders to "Enter the Continent of Europe, and in conjunction with other United Nations, undertake operations aimed at the heart of Germany and the destruction of her armed forces" The original codename for this invasion was "Operation Roundup"
This was eventually changed to "Operation Overlord"
The enormity of this task cannot be over stated, by the early months of 1944 Britain was a virtual army camp with 3.5 million troops, soldiers, sailors and airmen all training for the mammoth task that lay ahead. British, American, Canadian, Australians and New Zealanders, French, Belgians, Norwegians, Poles and Czechs along with the Dutch, all with the same objective. The Liberation of Europe from the Evil clutches of Hitler's occupation.

American troops, weapons and vehicles were shipped across the Atlantic to Britain for almost two years, this operation was code named "Bolero". Imagine an airforce consisting of 13,000 aircraft and 3,500 gliders! this was assembled for the great assault.
1,200 fighting ships, 1,600 merchant ships and 4,000 assault craft of various descriptions were at anchor in ports all over the southern coasts of England, including Cardiff in South Wales.
To keep the build up of all these men and their equipment a secret from the German spy network was an achievement in itself, but a secret it remained, many south coast towns were closed to the public, to prevent spying eyes…..

American Posters

Since 1942 British Intelligence had been gathering as much information as possible, looking for a suitable landing ground for the Liberating forces, one of the main priorities being, that the landing beaches had to be in range of fighter air cover from southern England.
The shortest and most accessible point was the Pas de Calais, this would give the allies a very short supply line indeed. The Germans under the command of Field Marshall Von Rundstedt also came to this conclusion, and therefore concentrated on reinforcing the Atlantic wall defences in this area.

The Pas de Calais was such an obvious landing area, the Allies decided against it, and went for their other location:- Normandy.
It was agreed that five landing beaches, covering a distance of 40 miles would be used. Five divisions would attack in the first wave, with four more divisions landing in the following 24 hours.
The Americans would land on the beaches which lay either side of the River Vire estuary, these were codenamed, "OMAHA" and "UTAH"
The British and Canadians would land on the eastern beaches which stretched to the River Orne estuary. These would be codenamed, "SWORD" "JUNO" AND "GOLD"