Civil War Union Brigadier General. Graduated from the USMA in 1851, placing 2nd out of 42. Served in the U.S. Corps of Engineers during his pre-Civil War career, being involved in the construction of fortifications in Charleston, SC, Fort Jefferson in the Dry Tortugas, Florida, and Fort Delaware. In June 1862 he was assigned to be the Chief Engineer of General Don C. Buell's Army of the Ohio. Promoted to Brigadier General, US Volunteers on April 4, 1863 (to rank from November 1862), and served as the Army of the Tennessee's' Chief Engineer around Nashville and Chattanooga, as well as commanding an engineer "Pioneer" Brigade. After participating in the Battles of Murfreesboro and Chickamauga, he then, by his own request, reverted from his Volunteer Generalship to his Regular Army rank of Major of Engineers (the only instance during the War of a general officer voluntarily reducing his rank). Served as chief of the Nashville defenses in the early part of 1864, then was assigned as an assistant to The US Army Chief Engineer. In May 1864 he was assigned to be the chief engineer of General Ambrose Burnside's independent IX Corps in operations around Petersburg, Virginia. On June 17, he was killed while scouting the area in front of General Orlando B. Willcox's division just before it was preparing to attack.