 By force of circumstances, he became commander of a battalion, joined the United States American Army Intelligence Service and served as a liaison officer with the British forces.Transferred with a promotion to the 58th Infantry Regiment of the 4th Infantry Division, he was severely gassed in August at the Second Battle of the Marne and sent back to the United States; the ship was torpedoed but did not sink.After returning to Harvard late in 1919 he had a breakdown as a result of the gas poisoning and "shell shock".