During the year leading up the war with mexico the united states used major disputes and reasons for going to war being manifest destiny, Rio grande boundary dispute, and slidell 's mission. Manifest Destiny was the word used throughout the 1840s which is the belief that Americans had the right and the duty, to expand westward across the North American, from the Ocean to Ocean.In order to have this destiny, Americans would have to go to war with Mexico. so in 1844, James K. Polk who won the election, He and the Democrats went with Manifest Destiny, a concept that stated that the U.S. was destined to expand across the continent and get as much land as possible. In Polk prestindestce he promised in his four step plan to get land westward and he did getting california and oregon. But in the process of wanting California he found it was difficult due to strained U.S. and Mexican relations. This lead to Slidell 's mission where the U.S. then sent John Slidell to Mexico City as an envoy instructed to buy California for $25 million. …show more content…
Polk at this time looking at mexico with no opposition turn to congress to declare war. congress did not want to because of the reasons Polk wanted war were invalid, but congress did say if they shot at us we would have no choice than to go to war with mexico. So frustrated Polk now forced a showdown, and on Jan. 1846, he ordered men under Zachary Taylor to march from the Nueces River to the Rio Grande, provocatively near Mexican troops. As events would have it, on April 1846, news of Mexican troops crossing the Rio Grande and killing of wounding 16 Americans came to Washington, and Polk pushed for a declaration of war. so with the Push by Polk, Congress declared war, and so began the Mexican-American War which mexico was trapped in fighting. So the following events lead up to mexico being trapped in a war with the U.S. manifest destiny, Rio grande boundary dispute, and slidell 's mission lead to the impacts of war between U.S. and