Fort Mason, established on July 6, 1851, near Mason, Texas, was a frontier army post created as part of a defensive line against Kiowa, Lipan Apache, and Comanche raids. Founded by Brevet Major Hamilton W. Merrill, it became one of the key antebellum posts in Texas and was associated with officers such as Albert Sidney Johnston, George H. Thomas, Earl Van Dorn, and Robert E. Lee, whose last U.S. Army command was there. The fort changed hands during the Civil War, declined after the U.S. Army returned in 1866, and closed permanently in 1871. Restored beginning in 1975, it is preserved for its military and regional significance.