Two weeks after war was declared on Spain, 85 volunteers, mostly members of the Territorial National Guard, filled the Territory's quota on May 5, 1898, as Troop A, 1st United States Volunteer Calvary, the famed Rough Riders. Examined and issued orders from Camp George W. Steele in the McKay building at 102 E. Harrison, they were sworn into federal service on the vacant lot across the street amid much fanfare, and the City of Guthrie presented a horse to Capt. Robert B. Husten, the troop commander. In San Antonio, Texas, they joined units from Arizona and New Mexico Territories for brief training before fighting as dismounted Troop D at the Battle of San Juan Hill on July 1 and 2, 1898, under Lt. Col. Theodore Roosevelt, who later visited veterans of the troop in Guthrie. In response to the clamor to serve, the formation of the First Territorial Infantry allowed more Guardsmen to enlist for the Territory's quota. Guthrie's group joined men from Pawnee to form Co I, and after mustering ceremonies on the vacant lot, the company marched under Capt. Harry C. Barnes to the depot to entrain for Ft. Reno. There they joined four other companies from Oklahoma and Indian Territories, and later units from Arizona and New Mexico joined them for training in Kentucky and Georgia before they were mustered out of service in 1899.