Asper raised a company for the
Civil War in 1861 and served as its captain. He was wounded in the
Battle of Winchester. He was promoted to the rank of lieutenant colonel in 1862. He mustered out of the service in 1863, because of wounds received in action. He became the Colonel of the
171st Ohio (a One Hundred Day Regiment) in May 1864 to August 1864. He served at the Prisoner of War Camp at Johnson's Island, Ohio. He was forced to surrender to John Hunt Morgan seven of the regiment's companies at Keller's Bridge, Kentucky, on June 12, 1864. The units were illegally paroled. Asper and the regiment returned to Johnson's Island. He mustered out at end of term of service. ==Other pursuits ==