...The original D-Day plan involved landing three divisions on the Normandy coast in the Caen-Bayeux area, with a simultaneous airborne assault on Caen. This template was later expanded by General Bernard Law Montgomery in charge of allied ground forces.
The component commanders were all British. Naval forces were commanded by Admiral Ramsay, ground forces by General Montgomery and Air Forces by ACM Leigh-Mallory. Since the whole invasion force could not land simultaneously, Montgomery decided that too few troops had been allocated to the initial attack, and directed that five divisions, from East to West: British, Canadian, British, and then two American, would form the first wave. This expanded plan included five divisions of 150,000 men in the main seaborne assault. Their flanks would be protected by three airborne divisions, the British 6th to the East and the US 82nd & 101st to the West.
Allied Planners believed the enemy would be able to commit up to 18 Divisions within one week of the Landings; 6 of these would be armoured. The real difficulty would be to hold off armoured counter attacks whilst the beachhead was at its weakest; trying to land supplies and reinforcements ashore knowing that a single Division in the battle line needed at least 600 tons of supplies every day.
A summer-time landing presented the obvious advantage of more daylight hours in order to be able to break out before Winter set in. A new imperative was the growing fear of secret rocket weapons which were expected to be targeted on London from enemy launch bases in Northern France and the Netherlands. Only 3 days in each lunar month offered the desired combination of moon and tide. The first of these was 5th to 7th June. The month of May had seen fine weather throughout, continuous sunshine and calm seas. The date was set, troops embarked on 3rd & 4th June, then the storm demanded a 24 hour delay.
Prior to D-Day, Allied bombing raids were twice as heavy at Calais than at the real landing target. Mine sweepers cleared shipping lanes that would never be used. The deception, in close harmony with extensive planning, was a resounding success. Blockades placed at both ends of the English Channel were unbroken. Surprise was complete and 130,000 men were put ashore in the first 6 hours.
