Allied land forces came from the United States, Britain, Canada, and Free French forces. In the weeks following the invasion, Polish forces and contingents from Belgium, Czechoslovakia, Greece and the Netherlands participated in the ground campaign; most also provided air and naval support alongside elements of the Royal Australian Air Force, the Royal New Zealand Air Force, and the Royal Norwegian Navy.

The Normandy invasion began with overnight parachute and glider landings, massive air attacks and naval bombardments. In the early morning, amphibious landings commenced on five beaches codenamed Sword, Juno, Gold, Omaha and Utah, with troops from the United States landing on Omaha and Utah, Great Britain landing on Gold and Sword and Canada landing on Juno. During the evening the remaining elements of the airborne divisions landed. Land forces used on D-Day sailed from bases along the south coast of England, the most important of these being Portsmouth.