"Following its original plan for the war, the United States sent its army from the Rio Grande, under
Taylor, to invade the heart of Mexico while a second force, under Col.
Stephen Kearny, was to occupy New Mexico and California. Kearny’s campaign into New Mexico and California encountered little resistance, and the residents of both provinces appeared to accept U.S. occupation with a minimum of resentment. Meanwhile, Taylor’s army fought several battles south of the Rio Grande, captured the important city of
Monterrey, and defeated a major Mexican force at the
Battle of Buena Vista in February 1847. But
Taylor showed no enthusiasm for a major invasion of Mexico, and on several occasions he failed to pursue the Mexicans vigorously after defeating them. In disgust, Polk revised his war strategy. He ordered Gen.
Winfield Scott to take an army by sea to
Veracruz, capture that key seaport, and march inland to
Mexico City. Scott took Veracruz in March after a siege of three weeks and began the march to Mexico City. Despite some Mexican resistance, Scott’s campaign was marked by an unbroken series of victories, and he entered Mexico City on September 14, 1847. The fall of the Mexican capital ended the military phase of the conflict."
from this site:
Mexican-American War | Definition, Timeline, Causes, & Facts
