Erskine commissioned into the
Scots Guards on 1 May 1917 and in August was deployed to the
Western Front. Erskine was injured in October that year but returned to the front in October 1918. He served as adjutant at the Guards Depot between 1921 and 1923, before serving as regimental adjutant of the Scots Guards until July 1932. In September 1933 Erskine was promoted to major and between 1933 and 1935 undertook training at the
Staff College, Camberley. In 1942 he was Major-General Commanding Troops & Commandant
Sudan Defence Force, and he was promoted to acting major general in April that year. From 1943 to 1945 Erskine was Brigade Commander, 148 Pre-OCTU Training Establishments. ==Personal life==