D-Day, took place on June 6, 1944, during World War II where Allied forces invaded northern France by means of beach landings in Normandy. It was the largest military naval, air and land operation ever attempted and marked the start of the campaign to liberate Nazi-occupied north-west Europe.

The D in D-Day merely stands for Day. This coded designation was used for the day of any important invasion or military operation. For military planners (and later historians), the days before and after a D-Day were indicated using plus and minus signs: D-4 meant four days before a D-Day, while D+7 meant seven days after a D-Day.

The codename Operation Overlord became known as the beginning of the end of World War II. Following the Battle of Normandy, which began on June 6, 1944, along a 50 mile stretch of beaches, including Utah and Omaha Beach, the attack became known as D-Day. While there are many explanations for the name, one reason may be due to the military countdown to the designated day and hour of the assault. D represented Day and H represented Hour in the military.

The battle liberated Northern France with more than 160,000 Allied troops from Britain, the United States, and Canada under the leadership of General Dwight Eisenhower. The troops manned more than 5,000 ships and 13,000 aircraft the day of the initial landing.

The landing of troops on the beaches of Normandy on June 6, 1944, known around the world as D-Day, was given the name Operation Overlord. Leading up to the attack, plans of deception were carried out to mislead Germany.