In 1776 officials in Mexico and Spain were not satisfied with the state of defense of the frontier of New Spain, especially in the western areas where the Apaches were more troublesome than ever. Accordingly, the Commandacy General of the Provincias Internas del Norte was created as a more effective organization for dealing with both Indians and foreign menaces to New Spain's northernmost colonial provinces. Headquarters was to be located at Arizpe in Sonora.
Charles III, King of Spain, appointed Brigadier Theodoro de Croix as the first Commandant General. Croix was born in France and had served the Spanish army for nearly 30 years prior to his appointment. He had come to New Spain in 1766 as a captain of his uncle's viceregal guard. Serving as commandant of the fortress of Acapulco and subsequently as inspector of all troops in the viceroyality, Croix was knighted as a caballero in the Teutonic order.
Croix assumed his new appointment on May 16, 1776. In special royal instructions King Charles III defined Croix's new authority with almost viceregal powers over the provinces of Texas, New Mexico, Coahuila, Nueva Vizcaya, Sinaloa, Sonora, and Baja California. In the new province of Alta California, however, he was to share authority with Viceroy Bucareli.
Although vested with almost supreme political authority over the Provincias Internas, and held responsible for the religious conversion of its Indians, Croix was to see to the military defense and civilian colonization of that enormous territory. He was urged to improve the local militia companies, and unify the operations of presidial troops in strict observance of the articles of the Reglamento of 1772. Croix reported directly to the minister of the Indies, who at that time was José de Gálvez.
Croix was appointed viceroy of Peru in 1783 relinquishing command to Philipe de Neve.