Civil War Union Brigadier General. The first man to climb Mt. Rainier (1853). At the outbreak of the Civil War, he was a captain in the 6th United States Regular Cavalry and served in the defenses of Washington and in the Peninsula Campaign. In September 1862, he was promoted to colonel and commander of the 2nd Ohio Volunteer Cavalry and sent to Ft. Scott in Kansas. From April 1864 until March 1865, he commanded a division of cavalry in the Army of the James, having been promoted to Brigadier General, US Volunteers on May 7, 1864. In March 1865, he took command of a Division of Colored Troops in the XXV Corps, and was at its head when it entered Richmond on April 3, 1865. In April and May, he was one of the commissioners who tried the conspirators who killed President Lincoln. After receiving brevets of Major General in both the Regular and Volunteer armies, he continued his service in the United States Army after the war. He became the Lieutenant Colonel of the 34th United States Infantry in 1866, Colonel of the 8th United States Infantry in 1874, and Brigadier General in 1891.