San Antonio Missions National Historical Park - Church and State on the Frontier (U.S. National Park Service)

For the Spaniards, the acculturation of the native peoples was a major means for securing their claim to vast lands in North America. With very few soldiers and settlers, Spain's claim to these areas in the face of encroachment by France and England, depended upon the success of the missions. Church and State were very closely linked, and the Spanish monarch granted various religious orders of the Catholic Church permission to found mission communities. Through instruction by these religious, communities of native converts were to emerge as part of an essentially medieval peasant society loyal to the crown on the frontier.

Along with the missions, a system of frontier military outposts, or presidios, was built as a means of protecting Spain's expanding territory. Generally these presidios were manned by a small force of soldiers. Wherever missions were built, a presidio was sure to be established nearby. This was the case in 1718 when a presidio was founded and named San Antonio de Béxar. A failed mission from within the jurisdiction of the presidio of San Juan Bautista del Río Grande in the province of Coahuila, Mexico relocated to the San Antonio River and was named Mission San Antonio de Valero.