Camp Peña Colorado, originally known as Cantonment Peña Colorado, was a post of the United States Army for almost fifteen years in the late 1800s. It was located about four miles southwest of the site of present-day Marathon in north central Brewster County. The post was built on Peña Colorada Creek near a large spring and beneath a high bluff called Peña Colorada (Spanish for "red rock," known also in English as Rainbow Cliffs), after which the creek, spring, and the army post itself were named (though the namers were not fastidious about Spanish grammatical gender).
Indians had apparently occupied the area around Peña Colorada Springs for thousands of years. In historical times the site had been a major stopping place on the Comanche Trail to Mexico. It was first occupied by United States soldiers in late August 1879, when Companies F and G, Twenty-fifth United States Infantry Regiment, moved there from Fort Stockton. The location lay on the road connecting Fort Clark and Fort Davis, was also on the prospective southern route of the transcontinental railroad, and was within practicable supporting distance of Fort Stockton to the northeast and Fort Davis to the northwest.
The establishment of Camp Peña Colorado was likely part of a larger army strategy to increase pressure on the Apaches living in the Trans-Pecos region, who were still forcefully resisting White settlement. It is probably not coincidence, either, that the outpost was founded the same month that Victorio and his Warm Springs Apaches escaped confinement on the Mescalero reservation in New Mexico and began their flight across the Southwest and Trans-Pecos.
The primary mission of the garrison at Camp Peña Colorado, as it turned out, was to provide escort through the region, perform scout duty, and pursue bandits, border raiders, horse thieves, and the like. In July 1880 the garrison was relieved by two companies of the Twenty-fourth United States Infantry. In September Company K, First Infantry, assumed garrison duties. This company, by monthly reports, indicated its chief occupations as road building and escort duty; it remained at the post for four years. During this time the spartan post consisted of several crude huts made of stone and mud and included two long, narrow buildings, one to serve as enlisted men's barracks and the other as a storehouse. Other buildings included two smaller huts for officers' quarters and a stone granary. The coming of the Southern Pacific Railroad in 1882 just to the north, however, brought material refinement in living conditions at the post with the increased availability of commodities from the East.
After July 1884 the garrison was principally composed of units of the Tenth United States Cavalry. The cavalry was needed for scouting missions and inspection of the Mexican border for Apaches and bandits. The Third Cavalry replaced the Tenth in the summer of 1885, when Geronimo and his band were causing trouble in Arizona and New Mexico. Units of the Third Cavalry made up the garrison until relieved by a temporary detachment of the Eighteenth Infantry.
Camp Peña Colorado was finally abandoned in late January 1893. By that time the settling of the country around the post was well along, and the need for United States Army troops in the Big Bend had shifted closer to the border. The site of the camp is located on Post Ranch, part of the Combs Cattle Company. The company's founder, David St. Clair Combs, early trail driver and prominent Texas rancher, donated the land around Peña Colorada Springs for a park in 1935. A historical marker was erected the next year on the location of the former outpost. The park is still enjoyed by residents of the area, among whom the spot is commonly known simply as the Post.