At the outbreak of World War II he was serving as a platoon commander leading a colonial unit in combat at Valvin and Sully-sur-Loire for which he would be awarded the Croix de Guerre. In 1942 he joined the Free French Forces in Africa. He trained with British commandos in Ceylon in 1944–1945 and then in January 1945 he was parachuted into Tonkin to rally French and Vietnamese to the Free French cause. He was in Hanoi on 9 March when the Japanese overthrew the Vichy French administration and he then escaped the city and walked to join up with French colonial forces retreating into southern China.