Fort Mason was established on July 6, 1851, by the U.S. Army as protection to the frontier and was named in honor of Lieutenant George T. Mason, who was killed in action near Brownsville on April 25, 1846. Albert Sidney Johnston, George H. Thomas, Earl Van Dorn, and Robert E. Lee, of the 2nd U.S. Cavalry, were stationed there at intervals from 1856 to 1861. Federal troops evacuated the fort on March 29, 1861, and it was reoccupied after the Civil War until 1869.