Turner became an ensign in the 2nd (The Queen's Royal) Regiment of Foot on 21 October 1795. After promotion to lieutenant, he saw service in Ireland and captured the Irish revolutionary Napper Tandy. Refusing to accept the reward offered for Tandy's capture, on 8 June 1803 the British government instead presented Turner with a Company in the Royal African Corps. He became a major in the Royal West India Rangers and was promoted to lieutenant-colonel on 28 May 1807. During the Peninsular War, Turner lost an arm at the Siege of Badajoz and retired on half-pay on 25 December 1818.