What does the "D" stand for in "D-Day?"

Strangely enough, the D in D-Day stands for Day, so this phrase could be literally translated to mean “Day Day.” While this phrase had been used in war prior to World War II to indicate the day of launching a major strategic maneuver, it has since come to signify the D-Day we know as the Allied Invasion of Normandy, France. D-Day was June 6, 1944, though originally scheduled for May that year. Under Dwight Eisenhower’s direction the invasion, also called Operation Overlord, landed 156,000 men on the beaches of Normandy to begin the massive effort that eventually led to Germany’s defeat.