At the outset of World War I, in August 1914, he volunteered for France and was sent to the front as a private. He was wounded at Charleroi and promoted to lieutenant. In October 1915 he was again wounded, at the battle of Artois, and further wounds in the same battle left him blind. He was left for four days, thought dead, then was taken as prisoner to Germany. He was eventually exchanged and returned to France through Switzerland.