At the beginning of the Civil War, he became a lieutenant and adjutant of the 13th Iowa Infantry Regiment. He fought at the battle of Shiloh and Corinth. He served as assistant adjutant general in the XVII Corps during the siege of Vicksburg and assistant adjutant-general to the Army of the Tennessee during the Atlanta Campaign. He was made a brevet brigadier general for service in the Atlanta Campaign and was assigned to an infantry brigade in the XV Corps during the Carolinas Campaign, but was only lightly engaged in fighting. He rose to the full rank of brigadier general of volunteers (1865) and was made a brevet major general at the close of the same year for gallant and meritorious services during the war.