what was d-day?
In the military, D-Day is the day on which a combat attack or operation is to be initiated. The best known D-Day is during World War II, on June 6, 1944âthe day of the Normandy landingsâinitiating the Western Allied effort to liberate mainland Europe from Nazi Germany. However, many other invasions and operations had a designated D-Day, both before and after that operation. The terms D-Day and H-Hour are used for the day and hour on which a combat attack or operation is to be initiated. They designate the day and hour of the operation when the day and hour have not yet been determined, or where secrecy is essential.