when the u.s. civil war started, he volunteered his service for the union army and was commissioned as a captain of volunteers and assistant quartermaster. he was later tapped to serve on the staff of major general ambrose e. burnside as assistant commissary of subsistence before promotion to major on july 22, 1862 and mustered in as aide-de-camp to general burnside. for the remainder of the war, he served with general burnside's command, the ix corps. during the war, he was charged with carrying a challenge for a duel from capt. charles gordon hutton to capt. j. m. cutts. on march 13, 1865 he was brevetted brigadier general of u.s. volunteers for "gallant and meritorious services at the battle of fredericksburg, va."