In World War I, the Legion demonstrated that it was a highly capable unit in modern warfare. It suffered 11,000 casualties in the Western Front while conducting brilliant defenses and spirited counter-attacks. Following the debacle in the Battle of France in 1940, the Legion was split between those who supported the Vichy government and those who joined the Free French under de Gaulle. At the Battle of Bir Hakeim in 1942, the Free French 13th Legion Demi-Brigade doggedly defended its positions against a combined Italian-German offensive and seriously delayed Rommel's attacks towards Tobruk. The Legion eventually returned to Europe and fought until the end of the Second World War in 1945. It later fought in the First Indochina War against the Viet Minh. At the climactic Battle of Dien Bien Phu in 1954, French forces, many of them legionnaires, were completely surrounded by a large Vietnamese army and were defeated after two months of tenacious fighting. French withdrawal from Algeria led to the collapse of the French colonial empire. The legionnaires were mostly used in colonial interventions, so the destruction of the empire prompted questions about their status. Ultimately, the Legion was allowed to exist and participated as a rapid reaction force in many places throughout Africa and around the world.