 On July 17, 1866, President Andrew Johnson nominated Warner for appointment to the grade of brevet brigadier general, U.S. Army, to rank from April 9, 1865, "for gallant and meritorious services in the field during the war" and the U.S. Senate confirmed the appointment on July 23, 1866.He mustered out of voluntary service on January 1, 1866, and resigned his regular army commission on February 13.After the war, Warner moved to Albany, New York, where he engaged in paper manufacturing as president of the Albany Card and Paper Company.