The Mexican American War was a conflict between the United States and Mexico. This was a battle for land where Mexico was fighting to keep what they thought was their property and the U.S. desired to retain the disputed land of Texas and obtain more of Mexico’s northern lands. There were two main causes of the Mexican War. First, the idea of “Manifest destiny” meaning the belief that America had a God-given right to occupy and civilize the whole continent. As large number of Americans migrated towards the west searching for land, the fact that most of those areas already had people living in them was ignored. Instead, an attitude and belief that democratic Americans would do a better job of running the lands than the Native Americans prevailed. President Polk shared and led the vision of Manifest Destiny, and did offer to buy the southwest land from Mexico. However, the Mexican government refused the offer, and because of this tensions continued to rise. The second major cause of the Mexican War actually started off with the Texas War of independence .During the 1830s, Mexico needed settlers in the under populated northern parts of the country and therefore allowed U.S. citizens to come and live in the Texas area as long as they took an oath of allegiance to Mexico and converted to Catholicism. Thousands of Americans accepted the invitation and migrated to the Mexican province of Texas. However, many of the new “Texans” were not satisfied with the way the Mexican government tried to run the province. So that led to the Texas Revolution began as both Mexicans and Americans living in Texas fought for independence from the Mexican government. A final victory resulted in the capture of the Mexican President who was forced to sign the Treaty of Velasco, granting Texas its independence.