After fighting well during the 1863 campaigns, Devin went on to command a division under Maj. Gen. Philip Sheridan during the 1864 Shenandoah Valley Campaign. As a reward for his outstanding performances during 1863 and the first half of 1864, he received a brevet to brigadier general of volunteers in August 1864. Devin was promoted to brigadier general of volunteers on March 15, 1863, with said commission to date from the October 1863 Battle of Cedar Creek. Late in the war, Ulysses S. Grant commented that, excepting Maj. Gen. Phillip H. Sheridan, Devin was the best cavalry officer in the Union service. At the end of the war, he was brevetted to major general of volunteers, and was appointed lieutenant colonel of the 8th U.S. Cavalry in 1866. In 1877, he was promoted to colonel of the 3rd U.S. Cavalry. He died in New York City on April 4, 1878. Of all, Devin and Wesley Merritt probably gained the most from their service under John Buford. Devin was known as either Old War Horse or Bufords Hard Hitter.