The Mexican-American War (1846-1848) denoted the principal U.S. outfitted clash primarily battled on outside soil. It set a politically partitioned and militarily ill-equipped Mexico against the expansionist-disapproved of organization of U.S. President James K. Polk, who trusted the United States had a "show predetermination" to spread over the mainland to the Pacific Ocean.

An outskirt encounter along the Rio Grande began off the battling and was trailed by a progression of U.S. triumphs. At the point when the residue cleared, Mexico had lost around 33% of its domain, including almost all of present-day California, Utah, Nevada, Arizona and New Mexico.

Reasons for the Mexican-American War
Texas picked up its freedom from Mexico in 1836. At first, the United States declined to join it into the association, to a great extent since northern political interests were against the expansion of another slave state. The Mexican government was likewise promising outskirt attacks and cautioning that any endeavor at extension would prompt war.

In any case, addition systems were immediately started after the 1844 race of Polk, who crusaded that Texas ought to be "re-added" and that the Oregon Territory ought to be "re-possessed." Polk additionally had his eyes on California, New Mexico and whatever remains of what is today the U.S. Southwest.

At the point when his offer to buy those grounds was rejected, he induced a battle by moving troops into a questioned zone between the Rio Grande and Nueces River that the two nations had already perceived as a feature of the Mexican province of Coahuila.