Roots of the conflict in North Mexico
The 1832 boundaries of Comancheria
, the Comanche homeland
The northern area of Mexico was sparsely settled and not well controlled politically by the government based in Mexico City. After independence from Spain in 1821, Mexico contended with internal struggles that sometimes verged on civil war and the northern frontier was not a high priority. In the sparsely settled interior of northern Mexico, the end of Spanish rule was marked by the end of financing for presidios and for subsidies to indigenous Americans to maintain the peace. There were conflicts between indigenous people in the northern region as well. The Comanche were particularly successful in expanding their territory in the Comanche–Mexico Wars and garnering resources. The Apache–Mexico Wars also made Mexico's north a violent place, with no effective political control.
Comanches of West Texas
in war regalia, c. 1830
The Apache raids left thousands of people dead throughout northern Mexico. When the United States Army entered northern Mexico in 1846 they found demoralized Mexican settlers. There was little resistance to US forces from the civilian population.
Hostile activity from indigenous people also made communications and trade between the interior of Mexico and provinces such as Alta California and New Mexico difficult. As a result, New Mexico was dependent on the overland Santa Fe Trail trade with the United States at the outbreak of the Mexican–American War.
Mexico's military and diplomatic capabilities declined after it attained independence and left the northern half of the country vulnerable to the Comanche, Apache, and Navajo. The indigenous people, especially the Comanche, took advantage of the weakness of the Mexican state to undertake large-scale raids hundreds of miles into the country to acquire livestock for their own use and to supply an expanding market in Texas and the US.
The Mexican government's policy of settlement of US citizens in its province of Tejas was aimed at expanding control into Comanche lands, the Comancheria. Instead of settlement occurring in the central and west of the province, people settled in East Texas, where there was rich farmland and which was contiguous to southern US slave states. As settlers poured in from the US, the Mexican government took steps to discourage further settlement, including its 1829 abolition of slavery.
In 1836, Mexico was relatively united in refusing to recognize the independence of Texas. Mexico threatened war with the United States if it annexed the Republic of Texas. Meanwhile, U.S. President Polk's assertion of Manifest Destiny was focusing United States interest on westward expansion beyond its existing national borders.
Designs on California
During the Spanish colonial era, the Californias (i.e., the Baja California peninsula and Alta California) were sparsely settled. After Mexico became independent, it shut down the missions and reduced its military presence. In 1842, the US minister in Mexico, Waddy Thompson Jr., suggested Mexico might be willing to cede Alta California to settle debts, saying: "As to Texas, I regard it as of very little value compared with California, the richest, the most beautiful, and the healthiest country in the world ... with the acquisition of Upper California we should have the same ascendency on the Pacific ... France and England both have had their eyes upon it."
US President John Tyler's administration suggested a tripartite pact that would settle the Oregon boundary dispute and provide for the cession of the port of San Francisco from Mexico. Lord Aberdeen declined to participate but said Britain had no objection to U.S. territorial acquisition there. The British minister in Mexico, Richard Pakenham, wrote in 1841 to Lord Palmerston urging "to establish an English population in the magnificent Territory of Upper California", saying that "no part of the World offering greater natural advantages for the establishment of an English colony ... by all means desirable ... that California, once ceasing to belong to Mexico, should not fall into the hands of any power but England ... daring and adventurous speculators in the United States have already turned their thoughts in this direction." But by the time the letter reached London, Sir Robert Peel's Tory government, with its Little England policy, had come to power and rejected the proposal as expensive and a potential source of conflict.
A significant number of influential Californios were in favor of annexation, either by the United States or by the United Kingdom. Pío de Jesús Pico IV, the last governor of Alta California, was in favor of British annexation.
Republic of Texas
The Republic of Texas
: The present-day outlines of the individual U.S. states are superimposed on the boundaries of 1836–1845.
In 1800, Spain's colonial province of Texas (Tejas) had few inhabitants, with only about 7,000 non-Indian settlers. The Spanish crown developed a policy of colonization to more effectively control the territory. After independence, the Mexican government implemented the policy, granting Moses Austin, a banker from Missouri, a large tract of land in Texas. Austin died before he could bring his plan of recruiting American settlers for the land to fruition, but his son, Stephen F. Austin, brought over 300 American families into Texas. This started the steady trend of migration from the United States into the Texas frontier. Austin's colony was the most successful of several colonies authorized by the Mexican government. The Mexican government intended the new settlers to act as a buffer between the Tejano residents and the Comanches, but the non-Hispanic colonists tended to settle where there was decent farmland and trade connections with American Louisiana, which the United States had acquired in the Louisiana Purchase, rather than further west where they would have been an effective buffer against the Indians.
In 1829, as a result of the large influx of American immigrants, the non-Hispanic outnumbered native Spanish speakers in the Texas territory. President Vicente Guerrero, a hero of Mexican independence, moved to gain more control over Texas and its influx of southern non-Hispanic colonists and discourage further immigration by abolishing slavery in Mexico. The Mexican government also decided to reinstate the property tax and increase tariffs on shipped American goods. The settlers and many Mexican businessmen in the region rejected the demands, which led to Mexico closing Texas to additional immigration, which continued from the United States into Texas illegally.
In 1834, General Antonio López de Santa Anna became the centralist dictator of Mexico, abandoning the federal system. He decided to quash the semi-independence of Texas, having succeeded in doing so in Coahuila (in 1824, Mexico had merged Texas and Coahuila into the enormous state of Coahuila y Tejas). Finally, Stephen F. Austin called Texians to arms, and they declared independence from Mexico in 1836. After Santa Anna defeated the Texians in the Battle of the Alamo, he was defeated by the Texian Army commanded by General Sam Houston and captured at the Battle of San Jacinto; he signed a treaty recognizing the independence of Texas.
Texas consolidated its status as an independent republic and received official recognition from Britain, France, and the United States, which all advised Mexico not to try to reconquer the new nation. Most Texians wanted to join the United States of America, but annexation of Texas was contentious in the US Congress, where Whigs were largely opposed. In 1845 Texas agreed to the offer of annexation by the US Congress and became the 28th state on December 29, 1845.