San Augustín de Ahumada Presidio was on the east bank of the Trinity River near the site of present-day Wallisville in northern Chambers County, forty miles west of Beaumont. It was established in 1756 and named after the viceroy, Agustín Ahumada y Villalón, Marqués de las Amarillas. The viceroy, following the suggestion of Governor Jacinto de Barrios y Jáuregui, ordered the construction of the presidio and its accompanying mission, Nuestra Señora de la Luz, at the site of a French trading post formerly occupied by Joseph Blancpain. Lt. Marcos Ruiz established the presidio, which was to hold a garrison of one officer and thirty soldiers. During the construction of the presidio and mission complex, often referred to as El Orcoquisac, Lt. Domingo del Río took command of the military post. In March 1759 an uprising by Orcoquiza Indians was averted only by the execution of a Spanish soldier who had killed one of the tribesmen. Conditions at San Agustín grew progressively worse as insects, disease, and the lack of supplies reduced the garrison. Discord over the proper site of the presidio arose. Del Río blamed many of the problems on Governor Ángel de Martos y Navarrete, and called upon Spanish officials to place the presidio under a captain who would be responsible only to the viceroy. Acting upon del Río's recommendations, the viceroy appointed Capt. Rafael Martínez Pacheco to command the military forces at El Orcoquisac in 1763. Martínez won the support of the Indians and missionaries and helped spur a temporary increase in missionary activity. The troops, however, protested against his methods as cruel and autocratic. Eighteen soldiers deserted, taking refuge with the French and petitioning for the captain's removal. Governor Martos suspended Martínez on September 13, 1764, and sent twenty soldiers with Lieutenant Ruiz to restore order at San Agustín. Martínez refused to submit to his arrest and escaped with a follower after Ruiz set fire to his house.
In the absence of a suitable captain, Lt. Melchor Afán de Rivera commanded the presidio. Having arrested the old lieutenant, Domingo del Río, on charges of perjury, Rivera appointed Cristóbal de Córdova to the post on May 3, 1765. Hugo Oconór arrested Ruiz six months later for his part in starting the fire, which had destroyed the governor's quarters and some barracks as well as Martínez's house. A hurricane demolished the Orcoquisac facilities on September 4, 1766. Although the presidio was rebuilt about a quarter of a league to the east of its former site, the Marqués de Rubí judged the Orcoquisac base useless when he inspected the northern provinces in 1767. Troops from the garrison had ousted French intruders in 1759; the cession of Louisiana to Spain in 1763 made the post obsolete. By 1772 orders to suppress the base on the Trinity had been made official. In the meantime, however, Captain Martínez Pacheco, having cleared the charges against him, again assumed command at El Orcoquisac in 1769. The following year he stripped much of his garrison to answer Governor Juan María Vicencio, Barón de Ripperdá's call for troops to check Apache depredations. In February 1771 Martínez and most of the remaining troops also departed. The three soldiers who had remained behind with Fray Ignacio María Laba were withdrawn a few weeks later. In the wake of Rubí's critical report, San Agustín was abandoned. Almost no traces of the Spanish occupation at Orcoquisac remain. The state of Texas erected a marker to denote the general location of the mission and the presidio in 1936. Thirty years later archeological excavations and the tireless research of John V. Clay pinpointed the exact site of San Agustín on the east bank of the Trinity River, near Lake Miller.