Fort Griffin, a strategic unit in the string of border and frontier outposts defending Texas settlers against hostile Indians and outlaws, was established in 1867. Its location is on the Clear Fork of the Brazos River in northeast Shackelford County. Lt. Col. Samuel D. Sturgis chose the site and led four companies of the Sixth United States Cavalry (F, I, K, and L) there on July 31. On June 3, 1868, companies of the Seventeenth Infantry under Lt. Col. S. B. Hayman joined the garrison. The new post was first called Camp Wilson but was soon renamed Fort Griffin after Gen. Charles Griffin, commander of the Military District of Texas, 1866–67 (see FIFTH MILITARY DISTRICT). Stone buildings were planned to replace the original picket, log, and frame structures, but soldiers' quarters, stables, and even the hospital were always temporary, some mere canvas-covered shelters.
The older posts of Belknap, Phantom Hill, and Chadbourne became subposts of the new Fort Griffin, which supplied garrisons for the first two. These subposts furnished escorts for stagecoaches, wagon trains, and surveying parties. In time, Griffin was the nucleus of the border-defense line from Fort Richardson at Jacksboro to the Big Bend country. Law enforcement at Fort Griffin was strengthened in 1877 by the arrival of over two dozen Texas Rangers led by Capt. G. W. Campbell. In July 1878 Campbell was replaced by Lt. George W. Arrington, whose Indian-fighting talents were preferred over those of the United States Army by the townspeople.
By 1879 the southern buffalo herd was depleted, and the fort and its outposts were within a settled area. On May 31, 1881, Capt. J. B. Irvine closed Fort Griffin and marched the single remaining army unit, Company A, Twenty-Second Infantry, southward to Fort Clark. Exodus from the town proper soon followed. Now only the ruins of Fort Griffin stand in Fort Griffin State Historic Site, fifteen miles north of Albany on U.S. Highway 283.