The Mexican War of 1846-1848 was of major importance to United States history, but has since fallen into the annals of obscurity. It was the nation's first war fought on foreign soil: a war that advocated the concept of "manifest destiny," the United States' God-given right to claim territory for the establishment of a society free democracy (Stevenson 2009). Although many historians claim that the war was forced on Mexico by slave owners hungry for new territory, President John Polk saw the war as an opportunity to defend the annexation of Texas, to establish the Rio Grande as a border and to acquire the Mexican territories of California. and New Mexico (Stevenson 2009). The annexation of the newly formed Republic of Texas sparked fierce debate on all sides. All the slave states wanted to bring Texas into the Union, but a number of free states opposed it because it would destroy the balance of power in Congress. Britain also denounced annexation because it wanted to stop American expansion (McGill 2009). The Mexican government, which still claims the disputed territory, has repeatedly warned that if Texas becomes a U.S. state, there would be war. Despite political controversy and the prospect of war, the annexation of Texas was important because Britain was negotiating an alliance with the Republic of Texas. This alliance would destroy the cotton trade in the South and stop American expansion (The Mexican War, 2006). Newly elected President James Polk, a strong advocate of American expansion, sent John Slidell to Mexico to negotiate an agreement on the territories of New Mexico and California and to seek Mexican recognition of the Rio Grande River. as the new US-Mexico border. It was important for the United States to establish its border...... middle of paper ...... evoking Mexico by slave owners hungry for new territory, President John Polk saw the war as an opportunity to defend the annexation of the country. Texas, establish the Rio Grande as the border and acquire the Mexican territories of California and New Mexico. Possibility of defending the annexation of Texas, establishing the Rio Grande as a border and acquiring the Mexican territories of California and New Mexico. References McGill, S. (2009). The War for Texas Independence and the Annexation of Texas. War for Texan Independence and Texas Annexation, 1. Retrieved from EBSCOhost.Stevenson, K. (2009). The Mexican War. Mexican War, 1. Taken from EBSCOhost.The Mexican War. (2006). Current Events, 106(3), 2. Retrieved from EBSCOhost. Tindall, GB and Shi, DE (2010). America, a Narrative History (8th ed., Vol. 1). New York, NY: W. W. Norton & Company.