Operation overlord was the name of the allied invasion of what northwestern country

France

In the United States, we typically refer to the World War II invasion of France by Allied forces at the beaches of Normandy as D-Day. "D-day," is actually military jargon for the day any operation goes into action, and H-hour" is the hour at which the operation commences. "Operation Overlord," as the planned incursion of France was called, has become the all-time most famous "D-Day" of American military forces. The Allies were seeking to retake France, which had fallen under German control early in the war.