The allies were mostly made up of American, British, and Canadian troops. The British contingent, however, consisted of entire squadrons of people from countries such as Poland, Czechoslovakia, Belgium, Denmark, and the Netherlands who had fled to Britain during the Nazi occupation of their countries. Australia, New Zealand, and Luxembourg also contributed soldiers to the effort to liberate France.

One of the most important and biggest contributions was by the French resistance. Already in the country, they made life difficult for the Germans by supplying intelligence to their allies and sabotaging means of communication and transport. In the lead-up to the battle, it is estimated that they destroyed 1800 railway engines. During the battle itself, they were able to guide the allies through the French terrain.

The allies landed on five beaches. Each one had its own code name. The Americans sailing from Plymouth in the UK landed on Utah beach in La Manche, the Americans sailing from Weymouth-Portland landed on Omaha beach on the west coast of Calvados, the Canadians (though they also joined forces with the British) sailing from the Isle of Wight landed on the Juno beach in Calvados, the British sailing from Southampton landed on Gold beach in Calvados, and the British sailing from Portsmouth landed on Sword beach in Calvados.

The D-Day invasion of Normandy was truly an international endeavor. There were coordinated efforts involving the armed forces of 10 different nations on the side of the Allies. The Axis defense of Normandy also involved the forces of several different nations, although they were all under German command.

Allies

• United States—The United States was the single largest contributor of armed forces on June 6, 1944. During the previous night, over 13,000 US paratroopers and nearly 4,000 glider troops landed in France in advance of the main invasion. 73,000 troops landed that morning on the two westernmost beaches, Utah Beach and Omaha Beach. There was also significant action taken by American naval and air forces in support of the invasion.
• Great Britain—Just over 62,000 soldiers from Great Britain landed on Sword Beach, Gold Beach, and Juno Beach. Much of the naval support, as well as some air support, was provided by British forces. Great Britain must also receive credit for hosting the staging areas in southern England prior to the invasion.
• Canada—About 30,000 Canadian soldiers took part in the invasion at Juno Beach. Many came with motorcycles, allowing them to quickly move inland and link up with airborne forces.
• France—Several hundred French commandos landed with British forces at Sword Beach. Also, an untold number of French underground operatives took part in action behind the German lines to sabotage enemy communications and transportation routes.
• Norway, Netherlands, Poland, Denmark—These countries were all under Axis control in 1944. However, free elements of their navies all took part in support operations in the English Channel.
• Australia—Around 3,000 Australians served with British units and participated in the invasion. Most were members of the Royal Australian Airforce and provided air support for the troops on the ground. About 500 Australians also served aboard British ships.
• New Zealand—No New Zealand units took part in D-Day. However, individual New Zealanders did participate as volunteers in the Royal Navy and Royal Force.

Axis

It is near impossible to have an exact breakdown of the soldiers' nationalities participating in the Axis defense in Normandy. Clearly, most were German, as every unit there was a German one under German leadership. However, many German military units during World War II had soldiers from other nations under German control within them. Therefore it is likely that there were soldiers from Austria, Czechoslovakia, Hungary, Yugoslavia, and other nations. Italian and Japanese forces did not participate.

There were actually more than six Allied nations that participated in the D-Day Invasion of the Normandy beaches on June 6, 1944. The United States, Great Britain and Canada provided the largest number of troops that fought against the German defenders.

UNITED STATES.  American infantry troops were assigned to attack the beaches designated as Utah and Omaha as well as the heights of Pointe du-Hoc. The First Army troops totaled approximately 73,000 men. U. S. airborne and naval troops also participated.

GREAT BRITAIN.  British troops assaulted the beaches at Sword, Juno and Gold. British Second Army troops numbered about 62,000 men. Naval and airborne troops also participated.

CANADA.  The 3rd Canadian Infantry Division and 2nd Canadian Armored Brigade assaulted Juno Beach. Canadian airborne troops also parachuted inland. Total numbers were approximately 30,000 men.

AUSTRALIA.  A small number of Australian officers were attached to British forces as observers, while as many as 3000 Australians were attached to British units.

NEW ZEALAND.  Several thousand Kiwis served in the British Royal Navy and Air Force.

FRANCE.  At least 500 Free French paratroopers participated in the invasion, and France contributed to the naval operations.

POLAND.  Atleast three Polish naval ships were engaged on D-Day.

NORWAY.  The Norwegian destroyer Svenner was sunk by German U-boats off Sword Beach, and several other Norwegian ships participated.

HOLLAND.  At least three Dutch gunboatsparticipated in the naval attacks.

BELGIUM.  Belgian paratroopers participated in airborne drops in the days before the invasion.