After Virginia's voters also ratified secession, and Confederate troops won at the First Battle of Manassas in July 1861, Grant recruited the King's Mountain Rifles in Abingdon and accepted a commission as its captain. His unit became Company H of the 37th Virginia Infantry, commanded by former judge Samuel V. Fulkerson. Capt. Grant served for less than a year in the unit, including during General Stonewall Jackson's Valley Campaign and the First Battle of Kernstown. His unit refused to re-elect him during the April 1862 reorganization, instead promoting Sergeant William F. Duff to captain of Company H.