Fort Clark was founded in June 1852 on land leased from rancher Samuel A. Maverick that included Las Moras Springs. The earliest buildings were jacales and palisado- type log huts, which joined the tents that housed most of the enlisted men. Stone buildings for living quarters, some extant, were constructed in 1856, and one palisado, a kitchen building, still stands. The fort was surrendered to state forces in March 1861, when Texas seceded from the Union. Abandoned in 1862, it was regarrisoned by U.S. troops in 1866.
The post–Civil War garrison included several hundred soldiers, who played a major role in patrolling West Texas to deter Indian attacks on travelers and settlements on both sides of the U.S.-Mexico border. Fort Clark also played a role in the mission of General Philip Sheridan, who was dispatched to Texas in 1866 by President Andrew Johnson to signal U.S. opposition to French intervention in Mexico. Sheridan had served as a junior officer at Fort Duncan (EL5) in 1854, but it was after a visit to Fort Clark in 1867 that Sheridan is said to have uttered his famous quip: “If I owned hell and Texas, I’d rent out Texas and live in hell.”
Most of the stone buildings on the central twenty-acre post were erected between 1873 and 1875. These included officers’ quarters, barracks, a hospital, a bakery, stables, and a guardhouse (which now houses the Fort Clark Guardhouse Museum). These one- and two-story limestone buildings surround the parade ground. The Black Seminole Indian Scouts served at Fort Clark from 1872 until 1914, playing a key role in attacks against Indian strongholds in northern Mexico in the 1870s.
Livestock rustling between South Texas and Northern Mexico and the threat of Mexican revolution from the 1890s through World War I kept Fort Clark expanding. General George Patton was stationed at Fort Clark in 1937–1938, and horse-mounted cavalry were garrisoned here until 1943. During World War II, parts of the post were used to intern German prisoners of war. The fort was deactivated in 1946 and sold. In 1971, it was purchased by a real estate development company and converted to a retirement community and recreation area.