On April 25, 1846, the Mexican Army attacked a group of United States soldiers under the command of General Zachary Taylor. The Mexicans killed about a dozen American soldiers and then besieged an American fort along the Rio Grande. While General Taylor called for reinforcements and with the help of rifles and superior weapons, the Americans managed to defeat the Mexicans in the battles of Polo Alto and Resaca de la Palma. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay After those battles ended, James J. Polk, former governor of Tennessee, told the U.S. Congress that “the cup of tolerance has been exhausted, even before Mexico crossed the border of the United States, invaded our territory and shed American blood on Americans alone.” Then, on May 13, Congress declared war, without the opposition of some Northern legislators. In my opinion, I think the Mexican-American War was justified because the term “destiny manifesto” was the expression of an idea on the part of the Americans. It was also a justification, because they wanted the territory and needed an excuse to push into a territory over which they had no control written during revolutionary times, with the desire for Canada in the period between the American War of Independence and the War of 1812. The Mexican-American War had a huge impact on the tension between the North and the Southern states because opposition to he expansion came from those who believed that the United States could not succeed as an experiment in self-government if it became too large. This involvement became known as the Whig Party. The United States initially believed that expansion would contribute to the nation's downfall. Then, shortly thereafter, the Northeast and East Coast thought they would lose the power of the United States and admitted more states into the Union. Finally, people who supported slavery in the North were grateful that Mexico's victory would lead to the incorporation of more slave territories into the United States. Please note: this is just an example. Get a custom paper from our expert writers now. Get a Custom Essay The annexation of Texas seemed to be a part of the natural exposure of the United States, which became part of the Louisiana Purchase. Then Mexico expanded more lands to Texas for the use of slave lands. John Quincy Adams, a member of the House of Representatives, believed that the push to annex Texas was a slaver's plan, although historians have shown that there was no slaver's plan for the United States.