Teodoro de Croix, soldier and government official in New Spain, was born in Prévoté castle near Lille, France, on June 20, 1730. He entered the Spanish army at age seventeen and was sent to Italy as an ensign of grenadiers of the Royal Guard. In 1750 he transferred to the Walloon Guards, bodyguards of the Bourbon kings of Spain. He was promoted to the rank of lieutenant in 1756 and was decorated in Flanders with the Cross of the Teutonic Order, which gave him the title of caballero. In 1760 Caballero de Croix was made a colonel in the Walloon Guards. In 1766, when his uncle Francisco, Marqués de Croix, went to New Spain as viceroy, Teodoro accompanied him as captain of the viceregal guard. The viceroy shortly appointed him governor of Acapulco. He became inspector of troops for New Spain with the rank of brigadier in December of that year and served in that capacity until 1770. The next year the Marqués de Croix ended his term as viceroy, and Teodoro sailed with him for Spain in company with José Bernardo de Gálvez Gallardo, who was retiring as inspector general. Poor sailing weather held up the voyage for five months in Havana. Thus Gálvez's young nephew, Bernardo de Gálvez, fresh from his first frontier command in Chihuahua, was able to overtake him and join the group for the rest of the voyage.
Croix's career undoubtedly benefited not only from his uncle's status but also from the close alliance of the Gálvez and Croix families. The subsequent careers of both the two older men and their nephews-which followed a well-planned course-testify, if not to a Croix-Gálvez power scheme, at least to their tremendous influence at court. While the elder Croix became commandant-general of the Spanish Army, José de Gálvez advanced to the important post of minister of the Indies. Don José thus was able to implement his recommendation for separating New Spain's northern provinces form the viceroyalty to deal more effectively with the Indian problem. Teodoro de Croix was named commandant general of the new Provincias Internas jurisdiction and assumed his duties on January 1, 1777, the same date that Bernardo de Gálvez became acting governor of Louisiana.
As commandant general Croix found himself facing the animus of the reigning viceroy, Antonio María de Bucareli y Ursúa, who had been deprived of a portion of his jurisdiction. Croix saw little improvement in frontier conditions from the work of Hugo Oconór, a Bucareli appointee, who had undertaken a reshuffling of presidios to establish a new defense line to conform with the Royal Regulations of 1772 (see NEW REGULATIONS FOR PRESIDIOS). The staggering toll of Indian depredations all across the frontier convinced him of Oconór's incompetence. Croix faced the necessity of reorganizing the presidial line again. He ultimately returned some of the forts to their original position and buttressed them with a secondary line of fortified towns. In August 1777 Caballero de Croix left Mexico to inspect his jurisdiction. The entourage crossed the Rio Grande near San Juan Bautista on December 24 and remained in what is now Texas until January 22, 1778. At Monclova, San Antonio, and Chihuahua, Croix convened war councils to discuss with frontier officers the means of confronting the Apache menace that was common to all the Interior Provinces. Out of the juntas came a request for the new governor of Louisiana, Bernardo de Gálvez, to join Croix in the Apache campaign, uniting a Louisiana force to 2,000 troops the commandant general hoped to obtain from the crown. Such plans, which might have enhanced the stature of both men, were doomed by the prospect of Spain's entry into the war that the North American colonists were waging against England.
Croix built up a more extensive military establishment over the entire northern frontier than any that had existed previously, with 4,686 militiamen and presidials under arms from Texas to Sonora. With his departure, however, the bulk of his policy was abandoned. On February 13, 1783, he was promoted to lieutenant general and relieved of his duties to become viceroy of Peru. Two years later his friend Bernardo de Gálvez, having achieved notable successes in the war with England, was appointed viceroy of New Spain to succeed his late father, Matías de Gálvez. If the Croix and Gálvez families had achieved a colonial dynasty, it was short-lived. Bernardo died in office in November 1786. Caballero de Croix served as viceroy of Peru from April 6, 1784, to March 25, 1790. In 1791 he was made a colonel in the king's bodyguard and a commander in the Teutonic Order. He died in Madrid in 1792.