 In the American Civil War, he enlisted on July 3, 1861, in Company C, Sixteenth Regiment, Michigan Volunteer Infantry, and served until July 16, 1865, with the rank of second lieutenant.After the war, Aplin returned to Michigan and engaged in mercantile pursuits at Wenona (later West Bay City and now part of Bay City).He was postmaster of West Bay City from November 1869 to June 1886.