In 1940, Germany forcefully took control of Western Europe, which involved the occupation of France, Belgium, and the Netherlands. To counter this and free these nations, the military forces of the United Kingdom, the United States, and Canada joined forces in the largest combined operation involving sea, air, and land forces ever undertaken.
This operation is now widely recognized as D-Day. On June 6, 1944, a significant number of American, British, and Canadian troops landed on the shores, supported by aircraft and naval vessels. They successfully secured all five intended beachheads. This achievement was made possible by the Allies' strategic deception, as they had misled Germany into anticipating an invasion in a different part of the French coast. Consequently, when the Allies arrived in Normandy, the German forces were unprepared.
D-Day marked a momentous turning point in the war. Before this, the Allied forces had no means of accessing Western Europe. However, with this victory, they established a foothold to push back against the Germans and begin the liberation of occupied countries like France and Belgium, which had come under Nazi control.