In April 1884, Vollrath joined the Ohio National Guard's Company A, 8th Infantry Regiment as a private. In June, he was promoted to regimental sergeant major. In June 1886, he received his commission as a captain when he was appointed to command the regiment's Company A. In March 1888, he was a candidate for the regiment's junior major position and was defeated by Charles W. F. Dick. In June 1892, he was again a candidate for a vacant major's position, and he was easily elected. After his promotion, Vollrath was assigned to command the 8th Regiment's 2nd Battalion.
