On June 6, 1944, American, British, Canadian, and other allied troops invaded Nazi-occupied Europe on what Supreme Allied Commander Gen. Dwight D. Eisenhower called a “great crusade.”
This force included five American divisions: The 1st Infantry Division, the 4th Infantry Division, the 29th Infantry Division, the 82nd Airborne Division, and the 101st Airborne Division.
They were joined by four British divisions: The 6th Airborne, the 3rd Infantry Division, the 50th (Northumberland) Infantry Division, and the 79th Armoured Division; and the 3rd Canadian Division.
German Field Marshal Erwin Rommel had hoped to halt the invasion on the beach, relying on the rapid deployment of Panzer divisions to crush the invasion. He supervised construction of the Atlantic Wall, and emplaced hundreds of thousands of obstacles and mines across the beaches.
The Allied plan involved several efforts to decoy the Germans into thinking the invasion would come elsewhere, with much of the focus being on the Pas-de-Calais region of France. The deception pulled some German troops away, but an attack by German vessels during an invasion rehearsal known as Exercise Tiger on April 28, 1944 proved disastrous as German warships discovered the allied forces and opened fire, killing nearly 800 U.S. troops.
Nearly 750 U.S. troops were killed in that attack, and the invasion was nearly cancelled until ten missing officers were recovered. Allied leaders were concerned they might have been captured and then possibly have revealed D-Day plans. One other consequence was that Adolf Hitler ordered increased defenses in Normandy after receiving reports of that naval skirmish.
The D-Day invasion force hit on five beaches, code-named Utah, Omaha, Gold, Juno, and Sword. The invasion was code-named Operation Neptune. Despite fierce German defenses, the Allied troops were able to establish a foothold on the European continent, making Nazi Germany’s defeat inevitable.
There is some confusion about what “D” in D-Day stands for. The most commonly accepted explanation is it simply was military terminology for “Day” and in that way the “D-Day” designation is somewhat redundant.