The fort was established in 1851 on Post Oak Hill on the front line of U.S. Army forts providing protection against Comanche, Kiowa, and Lipan Apache raids. As with other Texan forts, it provided military experience for soldiers in the period between the U.S.-Mexico War and the Civil War. Twenty-six future generals in Union and Confederate armies served here. Lt. Col. Robert E. Lee commanded the 2nd U.S. Cavalry at the fort from December 1860 to February 1861, his last command for the U.S. Army. Confederate forces took over the fort in March 1861. The U.S. Army reoccupied the fort in December 1866, remaining until 1869, when the State of Texas installed several companies of frontier forces. As the “frontier” moved west, Fort Mason was no longer strategic and was decommissioned in 1871.
The barracks were built of the local red sandstone, crudely chipped into irregular blocks and set in wide mortar joints. After the fort closed, the stones were scavenged by locals as a ready source of building materials. The current officers’ quarters building was reconstructed in 1975. Its southern veranda affords a panoramic view across the Comanche Creek valley. No other trace of the fort or of its parade ground remains.