Mexican American War

The Mexican War between the United States and Mexico began with a Mexican attack on American troops along the southern border of Texas on Apr. 25, 1846. Fighting ended when U.S. Gen. Winfield Scott occupied Mexico City on Sept. 14, 1847; a few months later a peace treaty was signed at Guadalupe Hidalgo.

The war between the United States and Mexico had two basic causes. First, the desire of the U.S. to expand across the North American continent to the Pacific Ocean caused conflict with all of its neighbors; from the British in Canada and Oregon to the Mexicans in the southwest and, of course, with the Native Americans. Ever since President Jefferson's acquisition of the Louisiana Territory in 1803, Americans migrated westward in ever increasing numbers, often into lands not belonging to the United States. By the time President Polk came to office in 1845, an idea called "Manifest Destiny" had taken root among the American people, and the new occupant of the White House was a firm believer in the idea of expansion. The belief that the U.S. basically had a God-given right to occupy and "civilize" the whole continent gained favor as more and more Americans settled the western lands. The fact that most of those areas already had people living upon them was usually ignored, with the attitude that democratic English-speaking America, with its high ideals and Protestant Christian ethics, would do a better job of running things than the Native Americans or Spanish-speaking Catholic Mexicans. Manifest Destiny did not necessarily call for violent expansion. In both 1835 and 1845, the United States offered to purchase California from Mexico, for $5 million and $25 million, respectively. The Mexican government refused the opportunity to sell half of its country to Mexico's most dangerous neighbor.

The second basic cause of the war was the Texas War of Independence and the subsequent annexation of that area to the United States. Not all American westward migration was unwelcome. In the 1820's and 1830's, Mexico, newly independent from Spain, needed settlers in the under populated northern parts of the country. An invitation was issued for people who would take an oath of allegiance to Mexico and convert to Catholicism, the state religion. Thousands of Americans took up the offer and moved, often with slaves, to the Mexican province of Texas. Soon however, many of the new "Texicans" or "Texians" were unhappy with the way the government in Mexico City tried to run the province. In 1835, Texas revolted, and after several bloody battles, the Mexican President, Santa Anna, was forced to sign the Treaty of Velasco in 1836 . This treaty gave Texas its independence, but many Mexicans refused to accept the legality of this document, as Santa Anna was a prisoner of the Texans at the time. The Republic of Texas and Mexico continued to engage in border fights and many people in the United States openly sympathized with the U.S.-born Texans in this conflict. As a result of the savage frontier fighting, the American public developed a very negative stereotype against the Mexican people and government. Partly due to the continued hostilities with Mexico, Texas decided to join with the United States, and on July 4, 1845, the annexation gained approval from the U.S. Congress.

http://en.wikipedia.org/wiki/Mexican-American_War