It was named in honor of George Thomson Mason, a United States Army second lieutenant killed in the Thornton Affair during the Mexican–American War near Brownsville, April 25, 1846.

At various times from 1856 to 1861, this was the home fort for Albert Sidney Johnston, George H. Thomas, Earl Van Dorn, and Robert E. Lee.

[5] Fort Mason, Texas, was established by the United States War Department as a front-line defense against Kiowa, Lipan Apache, and Comanche, on July 6, 1851.

The site on Post Oak Hill near Comanche and Centennial Creeks was chosen by Lieutenant Colonel William J. Hardee and surveyor Richard Austin Howard.

[13] The United States Army reoccupied the fort on December 24, 1866, under the command of General John Porter Hatch.

The Reconstruction era of the United States left its imprint on the fort's personnel, often leading to abandonment of duty and the resulting military discipline.