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. Texas was annexed by the United States in 1845. Mexico claimed the international border to be the Nuecos River, while the U.S. claimed the border to be at the Rio Grande. The Nuecos River runs roughly parallel to the Rio Grande about fifty to one-hundred miles northeast (the Texas side) of it. Therefore, by claiming their respective river boundaries, both countries were trying to expand their territory. When the Mexican army crossed the Rio Grande and skirmished with U.S. soldiers, President Polk declared that America had been invaded and American blood had been shed. These words…