Military of New Spain
The Military of New Spain played an insignificant role during the 17th century. The new Mexican society growing on the ruins left by the conquest was peaceful. A very limited number of regular troops, a couple of companies, were enough to keep the peace. The defense against external enemies was based on a limited number of fortified port cities. British aggression during the 18th century changed this. The Bourbon Reforms meant sending regular troops from the motherland to Mexico, raising several colonial regular regiments, and creating a local militia that also included people of color. The Northern frontier was the exception to the peacefulness of Mexico, with constant warfare with the nomadic Indians.
In sharp contrast to New France's militarization, but also in contrast to the experience of the Thirteen Colonies during the French and Indian Wars, the military in New Spain played an insignificant role during the 17th century. The new Mexican society growing on the ruins left by the conquest was peaceful. The indigenous population was unarmed and the few popular uprisings could easily be defeated and posed no serious threat to Spanish power. In the interior of Mexico, there were only a couple of regular companies, which in the event of disruptions could be strengthened with levies from the merchant, haciendados, and artisan classes. The geographical limitations insulated the interior of Mexico from external enemies. The silver mines in the north were secured by the large desert areas that a hostile army could not penetrate. The deadly tropical diseases on the Caribbean coast, the lack of suitable bases on the West Coast, and the long and poor road network, made the coastal regions of the Gulf of Mexico, the only areas in need of defense, against hostile powers, pirates and smugglers. 
The defense of New Spain against external enemies was based on a limited number of fortified port cities. On the west coast, there were no serious threats and the small Fort of San Diego in Acapulco, the port of call for the Manila galleon, was enough to meet all foreseeable contingencies. In the Caribbean, there were stronger fortifications to secure maritime communications with the mother country. The dominant winds led the silver galleons through the Straits of Florida; the fortress city of Havana, and the fortifications of St. Augustine in Florida, protected the only point where New Spain could really be threatened. On the surrounding mainland there were also strong fortress cities with regular garrisons. On the Mexican mainland it was Veracruz; in Yucatan, Campeche; and in the New Granada, Cartagena de Indias. As long as these fortresses could be held or quickly relieved, and as long as the large annual convoys could be assembled, there were no serious threats against New Spain.
During the eighteenth century, British aggression undermined the strategic position of New Spain. The British government used its naval dominance to create a global colonial empire. The conquest of New France and the acquisition of British India are perhaps the two best-known results of this aggression, but one of the first goals of the British government was the dismembering of the Spanish Empire which was perceived as both rich and weak. Initially, the seventeenth-century defense strategy of Spanish America, with strong fortresses and few mobile troops, succeeded in averting British aggression. When colonial troops from Carolina, under James Moore, besieged St. Augustine, Florida, the besiegers were driven away by Spanish colonial troops from Cuba. The full-scale British attack on Cartagena de Indias failed due to tropical diseases and the persistence of the defenders. Thousands of British soldiers, sailors and North American auxiliaries died. The Seven Years' War, however, saw the collapse of Spain's colonial defense strategy; the British taking both Havana and Manila in 1762, shocking the Spanish military and colonial establishment and leading to radical reforms, although both cities were returned by the Treaty of Paris 1763. 
The main goal of the Bourbon reforms in New Spain was to strengthen its defensive capabilities, although it led to significant social and political changes. Militarily, the reform aimed to strengthen the coastal fortifications, increasing the size of their garrisons by colonial troops, and to rotate unites from the mother country to the colonies on a regular basis. The military reforms in themselves did not alter social relationships, but since the military buildup in the mother country limited the means available for colonial defense, the reformers decided to arm the colonial population. Hence, a disciplined and organized permanent militia was created. Although mainly consisting of criollos, it was still considered new and dangerous to arm any others than peninsulares. The lack of suitable criollo recruits in some areas led the Spanish military authorities to organize militia units of pardos and morenos. The arming of people of color was an even greater breach with traditional policy than arming white Mexicans. 
The northern frontier, the Provincias Internas, with its population of nomadic Indians, was the only warlike area in Mexico. Apaches, Navaho, Comanches, and other native peoples not subordinated to the Spanish authorities, attacked the settled population, both the Spanish speakers, living on mission stations and cattle ranches or in mining villages, and the Pueblo Indians living in their prehistoric villages. The frontier area contained a third of Mexico's territory, and only one road, the Camino Real de Tierra Adentro, connected the frontier with Mexico City, 2,000 km away. The defenses of the northern frontier consisted of a series of forts or strongholds, presidios. They were garrisoned by a special type of soldiers, the soldados de cuera, whose equipment was adapted to Native American warfare. They took their name from the heavy leather armor they wore in the field as a protection against Indian arrows. Besides them, and their Indian scouts (Indios exploradores), Indian auxiliaries (Indios auxiliaries) under Spanish command fought against the nomadic Indians. . A special form of Indian auxiliaries was the Indios amigos that fought under their own captains.    
Military units of New SpainEdit
Eighteenth century before the Bourbon ReformsEdit
|Armada de Barlovento, Battalion of Marines||6||18||600|
|Dragoons of Veracruz||5||?||?|
|Infantry battalion La Corona||6||23||552|
Veteran Troops after the Bourbon Reforms (1799)Edit
|Ciudad de México||Compañía de Alabarderos de la Guardia del Virrey||25|
|Regimiento de Infantería fijo de México||979|
|Real Cuerpo de Artillería||1,910|
|Real Cuerpo de Ingenerios||9|
|Regimiento Veterano de Dragones de España [a]||461|
|Veracruz||Regimiento de Infantería de la Corona, fijo de Nueva España||979|
|Regimiento de Infantería fijo de Nueva España||979|
|Batallón de Infantería fijo de Veracruz||1,000|
|Puebla and Sonora||Regimiento Veterano de Dragones de México||461|
|Sonora and California||Compañía fija de Infantería Ligera Voluntarios de Cataluña||150|
|Acapulco||Compañía fija de Infantería de Acapulco||77|
|Isla del Carmen||Compañía fija de Presidio de Isla del Carmen||100|
|Compañía de Dragones de Presidio de Isla del Carmen||43|
|San Blas||Compañía fija de Infantería de San Blas||105|
|Campeche||Batallón fijo de Infantería de Campeche||550|
|Source:   |
Dragones de cueraEdit
|San Francisco de Conchos||50|
|San Pedro del Gallo||45|
|Nuestra Señora del Pasaje de Cuencame||45|
|Field companies of Parral and Durango||45|
|Santa Catalina de Tape Huames||9|
|Paso del Rio del Norte||49|
|Cerralvo, Calderita y León||20|
|San Antonio Casas Grandes||50|
|Santa Catarina de Tepehuenes||9|
Presidios and their strength in the several provinces:
- Bahía del Espíritu Santo, 51
- Adaes, 61
- San Sabá, 101
- Trinidad, 31
- Nuevo México
- Santa Fe, 81
- El Paso, 50
- Nayarit, 43
- Nueva Vizcaya
Junta de los Ríos, 50 Janos, 51 Guajoquilla, 51
Rio Grande. 33 San Francisco de Coahuila. 36 Santa Rosa del Sacramento. 52
- Nuevo León
San Agustín Ahumada, 27
Corodeguachi, 51 Guebavi, 51 Horcasitas, 51 Tubac, 51 Caborca (Altar), 51 Buenavista, 51
Loreto, 30 San José del Cabo, 30
- Nuevo Santander
- Santa Ana Calnargo, 13
- Villa de San Fernando, 10
- Villa de San Antonio Padilla, 5
- Nuestra Señora De Loreto de Burgos, 12
- Santa Maria de Llera, 12
- San Francisco de Güemes, 8
- San Juan Bautista Horcasitas, 11
- Dulce Nombre de Jesús Escandan, 9
- Soto la Marina, 11
- Cinco Señores de Santander, 22
- Reinosa, 11
- Santa Maria de Aguayo, 1
- San Antonio Padilla, 12
- Shy, John (1979). "Armed forces in colonial North -America: New Spain, New France, and Anglo-America." Records of the 4th International Colloquy on Military History. Ottawa: 10-26.
- Christon I. Archer (1977). The Army in Bourbon Mexico, 1760-1810. University of New Mexico Press.
- Kuethe, Allan J. (1986). Cuba, 1753-1815: Crown, Military, and Society. The University of Tennessee Press.
- Santiago, Mark. Eighteenth-Century Military Policy In Northern New Spain 2019-04-10.
- Polzer S.J., Charles W. Long before the Blue Dragoons: Spanish Military Operation's in Northern Sonora and Pimeria Alta 2019-09-04.
- "Pecos, the Plains, and the Provincias Internas 1704-1794." National Park Service: 2019-09-04.
- Mission Life 2012-04-10.
- Galván, José Luis Mirafuente (1993). "Las Tropas de Indios Auxiliares: Conquista, contrainsurgencia y rebelión en Sonora." Estudios de historia novohispana (13): 93-114.
- Bueno, José Maria (1984). Tropas Virreynales (I): Nueva España, Yucatan y Luisiana. Malaga.
- Albi, Julio (1987). La Defensa de las Indias (1764-1799). Instituto de Coperacion Ibero-Americana.
- Escamilla, Juan Ortiz (1997). Guerra y gobierno: los pueblos y la independencia de México. Universidad Internacional de Andalusia, Appendix 2.
- Bueno, José María (2014). Las Guarniciones de los Presidios de Nueva España: Los Dragones Cuera. Madrid: Ministerio de Defensa, p. 8.
- Bueno 2014, p. 9.
- Bueno 2014, pp. 11-12.