The Belknap Rifles, a San Antonio military company, was named for Augustus Belknap, who helped some twenty or thirty young men to organize and finance their own company after they were refused admission to the San Antonio Rifles. Robert B. Green, a graduate of the Agricultural and Mechanical College of Texas (later Texas A&M University), was chosen captain when the group was organized, on October 14, 1884. Aided by friends, families, and employers in securing uniforms and traveling expenses, the group participated in drills in nearby cities and on the San Antonio plazas. In competitive drills with similar groups the Belknap Rifles won more prizes on the drill field than any other militia company in the United States and made the highest score ever made in competition, at the Interstate Drill at Galveston in June 1889. In 1889 Samuel A. Maverick took the group by water to New York to the centennial of the founding of Manhattan. Their last official appearance as the Belknap Rifles was at the San Antonio fairgrounds in 1897.
With the outbreak of the Spanish American War, the Rifles volunteered in a body and enlisted as Company F, First Texas Volunteer Infantry, under Capt. Solon L. McAdoo, 1st Lt. W. B. Hamilton, and 2d Lt. Raymond Keller. A few of the original members of the group then organized the Belknap Cavalry and enlisted as Troop I, First Volunteer Cavalry, under Capt. John F. Green, 1st Lt. Hal L. Howard, and 2d Lt. John W. Tobin.