Camp Colorado was surrendered as a U.S. outpost at the beginning of the Civil War and became part of a frontier defense line from the Red River to the Rio Grande. It served as headquarters for the first Texas Mounted Rifles in 1861 and the Texas Frontier Regiment in 1863, and was manned by troops and Rangers in state and C.S.A. service to the war's end. Its forces performed valuable duty while patrolling and scouting to curb Indian raids and while rounding up draft evaders and deserters. Camp life was difficult, with constant peril of Indian attack and shortages of food, ammunition, supplies, and horses.