What was considered WWII's most critical day, when the US invaded Europe at Normandy?

The event referred to as WWII's most critical day is known as D-Day, which took place on June 6, 1944. This day marked the beginning of Operation Overlord, the Allied invasion of German-occupied France, specifically at the beaches of Normandy. The successful landings were a pivotal moment in the war, as they established a significant foothold for Allied forces in Europe and allowed for the liberation of Western Europe from Nazi control.

D-Day was carefully planned and executed, involving massive troop deployments, extensive logistics, and coordinated naval and air support. The success of this operation was crucial for shifting the balance of power in the Allies' favor and ultimately contributed to the defeat of Nazi Germany.

Other options refer to significant events in WWII but do not mark the specific moment of the Normandy invasion. Independence Day celebrates the United States' declaration of independence. VE Day, or Victory in Europe Day, is celebrated on May 8, 1945, marking the formal acceptance of Nazi Germany's unconditional surrender. VJ Day, or Victory over Japan Day, signifies the surrender of Japan, thereby concluding WWII in the Pacific.