[7] To close that gap, General Persifor Frazer Smith, commander of the Department of Texas, ordered on July 20, 1855, that an outpost be established where the Military Road crossed the Pecos River.

[10] To carry out Smith's orders, two companies of the 1st Infantry Regiment under the command of Captain Stephen Decatur Carpenter departed Fort Duncan on August 7, 1855.

[11] On August 20, 1855, Carpenter arrived at Live Oak Creek,[12] 4 miles (6.4 km) from the Military Road's crossing over the Pecos,[13] and established Camp Lancaster.

[14] The first structures at Fort Lancaster were jacales, huts with wood or earth walls with canvas roofs, and prefabricated buildings brought by wagon and assembled on-site.

[18] On July 9, 1857, a caravan of 40 men, 25 camels, and over a hundred sheep led by Edward Fitzgerald Beale,[18] a former US Navy lieutenant,[19] arrived at Fort Lancaster.

The caravan, part of a US Army unit formed in 1855 to test the feasibility of using camels as pack animals on the American frontier,[20] had encamped at a creek 2 miles (3.2 km) from Fort Lancaster.

He issued orders on February 24 and 27, 1861, for the garrisons of the forts along the Military Road to abandon their billets and march to the Gulf Coast for evacuation from Texas.

[12] On November 28, 1861, Confederate general Henry Hopkins Sibley arrived at Fort Lancaster as he was following the Military Road towards the New Mexico Territory,[28] which he hoped to invade and capture for the Confederacy.

[37] Archeological investigations in 1974[38] revealed that officers' quarters buildings had wood-plank floors, thresholds, and doorjambs fitted with iron pintels; the assumption is that doors were also of wood.

These carbonized remains were left in situ after being exposed during archeological investigations, photographed, and recorded by measured drawings using grid systems tied to "modern" architectural features of the park facilities.

Subsequent archeology in 1975 and 1976 revealed that wooden superstructure and flooring of site's commanding officer's residence and the sutler's store had likewise been destroyed by fire.

The ruins of Fort Lancaster were deeded in 1965 to the Crockett County government, which ceded it three years later to the Texas Parks and Wildlife Department (TPWD).

Associated with the 1974–1976 archeological investigations and as a preservation measure the archeologists in 1976 made adobes from untempered mud dug on site with hand tools.