 He then accepted a position as major of the 10th Vermont Infantry on August 26, 1862.He was promoted to lieutenant colonel on October 17, 1862, and assumed command of the regiment as colonel on April 26, 1864, replacing Albert B. Jewett, who had resigned.He commanded his regiment at the battles of the Wilderness, Spotsylvania, North Anna, Totopotomy Creek, Cold Harbor, and Cedar Creek.