During his adult life, Turner was a dentist before the outbreak of the American Civil War. He enlisted as a sergeant in Company K of the 2nd Rhode Island Infantry on June 5, 1861. Coincidentally, Company K was commanded by his brother, Captain Charles W. Turner, who had previously been commander of the Newport Artillery Company. On July 22 he was then commissioned as a 2nd lieutenant to fill a vacancy resulting from a casualty during the Battle of Bull Run which was fought the day before. He was promoted to 1st lieutenant on November 28, 1861 to fill a vacancy created by his brother's resignation from the Army.