Arthur entered the war in France on 15th August 1914 as part of the Regimental Medical Officer's team for the 1st Bn. Scots Guards. He was serving with the 1st Field Ambulance on 21st April 1915, when the Officer Commanding advised the A.D.M.S. that Arthur had been Mentioned in Despatches. On 22nd September 1916 he was evacuated with a gun shot wound received in Bottom Wood.