Wardrop was commissioned into the Royal Artillery in 1892. He served in the Great War, initially as a Brigadier in the Guards Division which formed part of the British Expeditionary Force. He served in France and took part in the Battle of Vittorio Veneto in Italy in 1918. After the War he was Commander Royal Artillery for the 3rd Army from 1918 and then Commander of British Troops in Palestine from 1921. He became Quartermaster-General for India in 1930 and General Officer Commanding-in-Chief for Northern Command in 1933; he retired in 1937. He lived at Upham in Hampshire.