On December 24, 1943, U.S. General Dwight D. Eisenhower was named Supreme Allied Commander. Then in February 1944, he was appointed as the Supreme Allied Commander of the Allied Expeditionary Force (SHAEF). He was charged with the planning and execution of the Allied landings on the Normandy coast under Operation Overlord.
(Taken from Normandy Landings – Wars of the 20th Century – World War II in Europe)
On June 6, 1944 (also called D-Day), the Allied 21st Army Group launched Operation Overlord, the invasion of the French coast of Normandy. The operation was delayed by one day from its earlier planned June 5 because of a storm in the English Channel. A lull in the inclement weather encouraged General Dwight D. Eisenhower, over-all commander of Supreme Headquarters, Allied Expeditionary Forces (SHAEF), to proceed with the invasion. Meanwhile in northern France, the bad weather lulled German authorities into believing that no invasion could take place, and on June 6, at the time of the Normandy landings, many high-ranking German commanders were away from their posts and participating in military exercises elsewhere.
The invasion began with British and American parachute and glider units making overnight landings in Normandy on the flanks of the target area, and securing bridges, exit routes, and capturing other key objectives. In the early morning of June 6, Allied air and naval units launched a massive bombardment of the Normandy coast and the immediate interior, which was followed by the landing of the ground forces. With a massive supporting naval armada of some 7,000 vessels, including 1,200 warships, 4,100 transports, and many hundreds of auxiliary vessels, Allied land forces ferried by amphibious landing crafts hit the Normandy coast at five points: in the western sector, U.S. forces in the beaches codenamed Utah and Omaha, and in the eastern sector, the British at the beaches named Gold and Sword, and the Canadians at Juno.
The British and Canadians established beachheads after meeting only moderate German resistance, while U.S. forces at Utah beach at the extreme right, facing the weakest resistance of all the sectors, also easily gained a foothold. At Omaha beach, U.S. forces met fierce enemy fire and suffered heavy casualties from the entrenched defenders occupying the high ground overlooking the beach. The Germans at Omaha Beach also comprised the veteran 352nd Infantry Division, the strongest formation in Normandy. Here, the Americans faced the real danger of being thrown back into the sea. The rapid landing of more troops and tanks, and more decisively, the bombardment of German positions by Allied warships and planes allowed the Omaha situation to ease by mid-day. By the end of D-Day (June 6), four of the five beachheads were secured, while Omaha was still being cleared and consolidated, and also still subject to distant enemy artillery fire.
Although the Allies had cause for optimism, they had failed to achieve their pre-invasion objectives for Day 1, that of establishing a beachhead up to a distance of 6–10 miles (10–16 km) inland, of linking up the three central beachheads, and capturing the towns of Caen, Saint-Lo, and Bayeux. In the following days, the Allies expanded their beachheads, and on June 9, 1944, two artificial harbors towed from England became operational in Normandy, one each in the American and British-Canadian sectors, where large numbers of troops, equipment, and supplies were unloaded. The Allied plan was to fortify and then expand their positions faster than the Germans could send reinforcements to Normandy. On June 7, 1944, the British and Canadian sectors linked up, joined the next day with the American-held Omaha beachhead, and on June 11, by the Utah sector – a continuous Allied frontline thus was established. The delay in the link-up by the Utah sector resulted from the Germans receiving reinforcements there and mounting a determined stand against American attempts to expand the beachhead.
On D-Day, the Allies landed some 130,000–156,000 troops. By June 11, this number had grown to 330,000 troops, including 150,000 vehicles and 570,000 tons of supplies. By July 4, Allied troops landed were one million, which now included French, Polish, Dutch, Belgian, Czech, and Greek units. By then, the Allies held an overwhelming superiority in manpower and weapons over the Germans, and had achieved full mastery of the skies over France and water lanes along the French northern coast.
The Allied landings experienced a major, temporary setback when a powerful storm struck the French coast on June 19–22, 1944 that completely destroyed the artificial harbor in the American sector, as well as sank or beached hundreds of Allied ships and destroyed some 140,000 tons of supplies. As a result, the Allies scaled back or temporarily stopped all combat operations due to a shortage of ammunition and supplies.
Operation Overlord caught the Germans completely by surprise, which indicated the overwhelming success of the Allied deception strategy under Operation Bodyguard. Allied planners believed that the sheer number of invasion ships steaming across the English Channel would surely be detected by the Germans within a few hours, and thus were astonished that German intelligence had failed miserably. Even after the landings had taken place and for many weeks thereafter, Hitler continued to believe that Normandy was merely a diversion for the main attack at Pas de Calais, and refused to allow the armored reserves be brought to Normandy, as requested by General Gerd von Rundstedt, commander of German forces in the West, who by late June 1944, was convinced that the Normandy landings were indeed the main Allied attack. German forces at Normandy did launch a number of sporadic counter-attacks, including a major thrust on D-Day that advanced to the coast at Lue-sur-Mer. But lacking reinforcements and air and artillery support, these German counter-attacks were easily repulsed.
Following D-Day, the Allies rapidly extended their Normandy beachheads and continued to push back the Germans. On June 7, 1944 (D-Day + 1), an advance by Canadian forces toward Caen was stopped decisively by the Germans north of the town. One week later, on June 13, an attack by British armor toward Villers-Bocage was repulsed with heavy losses by German panzers. And in late June 1944, a British attempt to outflank Caen also failed to achieve a breakthrough. The Germans concentrated their forces in the western sector, particularly in the defense of Caen, since its capture would allow an Allied breakout into the open plains of northwest France, where the sheer weight of Allied manpower and weapons would be overwhelming.