The significance of the D-Day invasion during World War II, which took place on June 6, 1944, lies in its pivotal role in the liberation of Western Europe from Nazi control. Known as Operation Overlord, Allied forces, comprising American, British, Canadian, and other troops, launched a massive amphibious assault on the beaches of Normandy, France. This operation marked the beginning of a major offensive against German forces in Western Europe. The successful landings enabled the Allies to establish a foothold, leading to the liberation of occupied territories and ultimately contributing to the defeat of Nazi Germany in 1945.