Calais and Normandy have their pros and cons, with Calais having the advantage of being the closest to England, only 33 kilometers, and close to Germany itself; The disadvantage is that the German army has the strongest defense force here, and the defenders are elite troops, the fortifications are complete and strong, and there is no large port nearby, and there is also a lack of inland communication lines, which is not conducive to the development of depth after the landing. Although Normandy was far away from the British, it had the advantage that the German defense was weak, the terrain was open and could deploy 30 divisions at the same time, and the third was that it was only 80 kilometers away from Cherbourg, the largest port in northern France.

After several trade-offs and comparisons, "Kausak" chose Normandy and began to formulate a specific plan on May 12, 1941, with "Overlord" as the code name for the battle plan and "Sea King" as the code name for the relevant naval operation. It was initially planned to land three divisions on three beachheads, later known as "Omaha", "King" and "Juno", at a 32-kilometre-wide stretch between Kalantan and Caen, with two brigades airborne.

The second echelon, consisting of 8 divisions, will occupy Cherbourg in two weeks. The biggest problem in the whole plan was the port problem, that is, how to solve the logistical supply of the troops before the capture of Cherbourg, knowing that the beaches of Normandy were mostly windy and rough weather in May and June, and the landing beachhead alone could not guarantee logistical supplies - this seemed to be an insurmountable difficulty.

Helpless, the naval representative of the "Kausak" British Rear Admiral John? Hughes? Hallette remembered Mountbatten's joke at a meeting that since there was no natural harbor, build an artificial harbor. Therefore, it was suggested that the manufacturing of accessories should be assembled into an artificial port to solve the problem. There was no other solution, and his idea was approved. On May 15, Morgan submitted the outline of the "Overlord" plan to the British-American Joint Chiefs of Staff Committee for approval. The Anglo-American-Soviet Tehran Conference decided to launch Operation Overlord in May 1941.

U.S. Army General Dwight D. Eisenhower was appointed Supreme Commander of the Allied Expeditionary Forces in Europe and arrived in London on May 17, 1941. Eisenhower read the Morgan Plan. Believing that the assault front was too narrow and that there was a lack of sufficient assault force in the initial attack, he proposed a revision to expand the landing front to 80 km, increase the first echelon from three divisions to five divisions, increase the number of landing beachheads from three to five (new "Utah" and "Sword" beachheads), and increase the airborne forces from two brigades to three divisions.

Eisenhower convened the first meeting of the Supreme Command of the Expeditionary Force at the Norfolk Hotel, at which the program for landing operations was clarified, making this meeting the most important military conference of World War II.

Subsequently, the Anglo-American Joint Chiefs of Staff Committee approved the outline of the "Overlord" plan and the revised operational plan. But with it, the need for landing ships also increased. In order to ensure the availability of sufficient landing ships, the Anglo-American Joint Chiefs of Staff Committee decided to postpone the landing date until early June.

With the postponement of the landing date (code-name D-Day) to early June, the Allied High Command began to set specific dates and timings, a complex matter of coordination. Each branch of the armed forces puts forward different requirements according to its own needs. The army demanded to land at the climax. to reduce the amount of time troops are exposed to the beach.

The Navy demanded to go ashore at low tide in order to minimize damage to the landing craft by obstacles; The Air Force requires moonshine to facilitate the identification of ground targets by the Airborne Forces. Finally, after careful consideration, a plan was scientifically drawn up to suit the various branches of the armed forces, and the landing was to be made between high tide and low tide, because the tides of the five beachheads were different, so five different landing times (code H time) were prescribed, and the D day was arranged on the day of the full moon, and the airborne landing time was 1 a.m., and the landing date that met the above conditions was only two sets of three consecutive days in June 1941, June 5 to 7 and June 18 to 20, and finally the first day of the first group, that is, June 5.

The purpose of the Normandy landing campaign was to cross the English Channel and seize a strategic landing ground in northern France, creating the conditions for the final defeat of Germany in the second European theater. The campaign was to land in Normandy, to seize the landing field, to expand the landing field to a width of 100 kilometers and a depth of 100 kilometers.

It was planned to first parachute 2 American paratrooper divisions on the right flank of the landing site to cut off the German reinforcements from Cherbourg and cooperate with the landing force to seize the "Utah" beachhead; Airborne 1 British paratrooper division on the left flank to seize the crossing point of the Conn Canal.

Then the first batch of 8 reinforced battalions of the landing force landed at 5 beachheads, established landing grounds, and after consolidating and expanding the landing grounds, the follow-up troops went ashore, the right flank first captured Cherbourg, and the left flank advanced to the line from the Conn River to Saint-Ro, covering the attack of the right flank troops; In the second stage, he captured Okana, Bayeux, Izzini, and Carentin, and in the third stage, he captured Bretagne, advanced to the Seine, and took Paris directly.

The post of Supreme Commander of the Allied Forces was originally intended to be filled by experienced British generals, but Churchill knew that the number of American troops would greatly exceed that of the British after landing, so he took the initiative to propose that American generals take the position. President Roosevelt originally planned to appoint Marshall, chief of staff of the Army, but considering that it was more necessary for Marshall to coordinate in Washington, Marshall recommended Eisenhower, who was then commander of the Allied Mediterranean theater, to take the post. Other members of the Supreme Command were: Deputy Commander British Air Marshal Ted, Chief of Staff US Army Lieutenant General Smith, Deputy Chief of Staff British Army Lieutenant General Morgan, Army Commander British Army General Montgomery, Navy Commander British Navy Admiral Ramsay, Air Force Commander British Air Force Admiral Mallory.

The army had four army groups: the British 2nd Army, commanded by British Army Lieutenant General Temple, with 5 corps and 13 divisions, landed on the "Gold" and "Sword" beachheads on the left flank. The 1st Canadian Army, commanded by British Army Lieutenant General Duncan? Grenium, with 1 corps and 3 divisions, landed on the beachhead of "Juno", and the above two armies attacked Caen as the left flank.

The U.S. 1st Army, commanded by U.S. Army Lieutenant General Bradley and with 5 corps and 14 divisions, landed on the "Omaha" and "Utah" beachheads, and attacked St. Lo and Carentin as the right flank, which was the main direction of attack. The three armies formed the 21st Army Group, commanded by British Army General Montgomery, which was the first echelon of the landing force.

The U.S. 3rd Army, commanded by U.S. Army Lieutenant General Patton, has jurisdiction over 4 corps and 9 divisions, and is directly under the command of the Supreme Command.

The Army will deploy a total of 86 divisions, including the 2nd, 3rd, 4th, 5th, 6th, and 7th Armored Divisions of the United States, the British Praetorian Armored Division, the 7th, 11th, and 79th Armored Divisions, the 4th, 9th, and 27th Armored Brigades, the 2nd French Armored Division, the 1st Polish Armored Division, the 4th Canadian Armored Division, and the 2nd Armored Brigade. The models of tanks used are American-made M4A1, M5A1, and M3A3 tanks, British Churchill, Cromwell tanks, DD amphibious tanks, M10M36 tank destroyers, Churchill bridge-building tanks, and Crab minesweeper tanks. (To be continued......)

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