He joined the army in September 1861 as a
first lieutenant and regimental
quartermaster of the
64th Ohio Infantry. He was known by some accounts as the first officer to join the "Sherman Brigade" which was raised under the direction of Ohio Senator John Sherman. In December 1861, he was assigned to the depot at
Bardstown, Kentucky. Following the capture of
Nashville, he was placed in charge of the land and river transportation in that city and after the
Battle of Shiloh, he was ordered to the front and placed in charge of the field transportation of the
Army of the Ohio. It was following the capture of Corinth that he returned home on sick leave and when he had sufficiently recovered he was ordered to Maine as Chief Quartermaster of the state, where he quickly became friends with Congressman
James G. Blaine. He was then transferred to
Pittsburgh, Pennsylvania, and placed in charge of transportation and army stores for the
Department of the Susquehanna, and then to Washington D.C. as post quartermaster until June, 1865, when he was made a Colonel and inspector of the quartermaster's department. He was retained on duty at the war office with Secretary of War
Edwin Stanton until November, when he was ordered to Cincinnati as Chief Quartermaster of the
Department of the Ohio. At his own request, Brinkerhoff was mustered out of the volunteers on September 30, 1866. In recognition of Brinkerhoff's service, on December 11, 1866,
President Andrew Johnson nominated Brinkerhoff for appointment to the grade of brevet brigadier general to rank from September 20, 1866, and the
U.S. Senate confirmed the appointment on February 6, 1867. He was the author of a volume entitled, "The Volunteer Quartermaster," a treatise which was considered the standard guide for the officers and employees of the quartermaster's department up until the First World War. ==Postbellum career==