The 177 French commandos of the Kieffer group were the only French troops to participate in the D-Day landings. The Third Reich had built extensive fortifications along the Atlantic Wall from Spain to Norway. Allied forces gathered troops, weapons, and ships in England before launching bombing and parachute operations and crossing the English Channel to land on five Normandy beaches: Sword, Juno, Gold, Omaha, and Utah on D-Day. Two artificial harbors, Mulberry A and B, were constructed to supply reinforcements and material to the Allied forces after they established a foothold in Normandy. The massive D-Day invasion of Normandy was described as "The greatest landing in history."