Walker returned to North Brookfield to recuperate and resigned his commission on January 8, 1865, as a result of his injuries and health. At the end of the war, Maj. Gen. Winfield Scott Hancock recommended that Walker be brevetted as a brigadier general of U.S. Volunteers in recognition of his meritorious services during the war and especially his gallant conduct at Chancellorsville. On July 9, 1866, Walker was nominated by President Andrew Johnson for appointment to the honorary grade of brevet brigadier general, U.S. Volunteers, to rank from March 13, 1865 (when he was age 24), for gallant conduct at the battle of Chancellorsville and meritorious services during the war. The U.S. Senate confirmed the appointment on July 23, 1866.