Bryan arrived on the Western Front in France in April 1918 and was attached to the Royal Sussex Regiment at Friville in the Somme sector. He saw action in the Hundred Days Offensive and was in action until the end of the war. After the Armistice he volunteered for service in the Army of Occupation on the Rhine and was stationed in Germany until the Treaty of Versailles was signed in 1919 and was transferred to the Territorial Reserve in February 1921.