 He reenlisted in 1861 for three years and was elected first lieutenant of Company K, Seventy-sixth Regiment, Pennsylvania Volunteer Infantry.He was detailed on the staff of General Barton as assistant quartermaster and aide-de-camp, which position he held under General Barton and General Galusha Pennypacker until the expiration of his term of service in 1871.After the war Brumm resumed the study of law, and was admitted to the bar in 1871.