Operation Overlord was the code name for the
Battle of Normandy, the
Allied operation that launched the successful invasion of German-occupied
western Europe during
World War II. The operation commenced on 6 June 1944 with the
Normandy landings (
Operation Neptune, commonly known as
D-Day). A 1,200-plane
airborne assault preceded an
amphibious assault involving more than 5,000 vessels. Nearly 160,000 troops crossed the
English Channel on 6 June, and more than two million Allied troops were in France by the end of August.