The Normandy landings were the landing operations and associated airborne operations on Tuesday, 6 June 1944 of the Allied invasion of Normandy in Operation Overlord during World War II. Codenamed Operation Neptune and often referred to as D-Day, it was the largest seaborne invasion in history. The operation began the liberation of France (and later Western Europe) and laid the foundations of the Allied victory on the Western Front.

D-Day – 6 June 1944 – was the largest amphibious invasion in the history of warfare. The statistics of D-Day, codenamed Operation Overlord, are staggering. The Allies used over 5,000 ships and landing craft to land more than 150,000 troops on five beaches in Normandy. The landings marked the start of a long and costly campaign in north-west Europe, which ultimately convinced the German high command that defeat was inevitable.

Did You Know?
D-Day was the start of Operation ‘Overlord’. On D-Day, 6 June 1944, Allied forces launched a combined naval, air and land assault on Nazi-occupied France. The ‘D’ in D-Day stands simply for ‘day’ and the term was used to describe the first day of any large military operation.

Early on 6 June, Allied airborne forces parachuted into drop zones across northern France. Ground troops then landed across five assault beaches – Utah, Omaha, Gold, Juno, and Sword. By the end of the day, the Allies had established a foothold along the coast and could begin their advance into France.

Sources:
https://www.iwm.org.uk/history/the-10-things-you-need-to-know-about-d-day