When various revolutions mostly forced the Europeans out of the continent, Texas ceased to belong to Spain and France to become a part of the Mexican Empire; later it was an independent country, and currently one of the 50 states of the United States. During a short period, rebellious Texas again separated from the U.S. to join the Confederate States of America with other secessionist states.
Of course, the most important war of all for Texas came in the early 19th century, and the common story heard in America is about rebellion against intolerance, oppression and Mexican cruelty. The Battle of the Alamo in particular, surrounded by legend and testimonies of heroism, is a textbook example of the fight for freedom, comparable to the Jewish defenders during the Roman siege at Masada. The words "martyrs" and "Mexican tyranny" are almost always present in the recounts, and "Remember the Alamo!" is both a slogan of self-glorification and martyrdom that remains one of the most famous phrases in America.
Naturally, this typical account is portrayed through rose-colored glasses. As in every story, everything depends on which side readers are positioned and whose histories they´re reading. The Texas Revolution certainly pursued freedom, but not for the tired, poor and huddled masses yearning to breathe free, the homeless or the wretched refuse of alien shores; it was rather the freedom to suck in land from a weak country and to preserve slavery in the cotton fields, added to enthusiasm for cheap land and inexhaustible natural resources.
The policy of manifest destiny increased tensions with Mexico in the 1840s. Mexico's northern half formed the western border of the territory bought in the Louisiana Purchase. Naturally, notions of the United States expanding to the Pacific Ocean alarmed Mexico, which held what is today the west coast of the United States.
However, Mexico first came to regard American expansion as a serious problem with the immigration of Americans into its northeastern territory. These Americans declared independence from Mexico and created a nation in the Mexican province of Texas. After winning independence in 1836, Texas became an independent republic.
Texas formally asked to be annexed by the United States in 1845. This annexation angered the Mexican government, which still considered Texas to be part of its territory. Mexico had previously warned that the annexation of Texas would cause Mexico to declare war on the United States.
When the annexation bill was passed by Congress, it included an additional provocation to Mexico: it claimed that the southern border of Texas was the Rio Grande. The actual territory controlled by the Republic of Texas did not extend nearly to the Rio Grande, and this border would represent a further loss of territory to the United States.
When a Mexican patrol attacked American cavalry in the disputed area north of the Rio Grande, President Polk went to Congress for a declaration of war. The declaration passed on May 13, 1846. The war against Mexico was unpopular with the opposition Whig party, especially in the North. Opponents of the war denounced it as a war of aggression, and denied that there had been a valid reason for war.
Small American military units were quickly able to occupy key points in California, including San Francisco and Los Angeles. Although California was sparsely populated, some Mexican inhabitants formed an effective resistance which was eventually put down in 1847 by American reinforcements. Subsequently, a larger American army was sent to invade central Mexico, and managed to capture the Mexican capital, Mexico City, on September 13, 1847. Although a large Mexican army was still fighting American forces in northeast Mexico and Texas, news of the capital falling caused it to retreat to try to retake the capital. After the defeat of the last Mexican army, major hostilities ended.