USA HISTORY

Detailed explanation-1: -On May 12, 1846, the United States Senate voted 40 to 2 to go to war with Mexico. President James K. Polk had accused Mexican troops of having attacked Americans on U.S. soil, north of the Rio Grande. But Mexico claimed this land as its own territory and accused the American military of having invaded.

Detailed explanation-2: -Pres. James K. Polk oversaw a large territorial expansion of the United States. He advocated for annexation of Texas and aggressively prosecuted the resulting Mexican-American War, which added much of the Southwest and California to the country’s territory.

Detailed explanation-3: -In late April 1846, Mexican troops crossed the Rio Grande and killed eleven U.S. soldiers. In response, Polk requested a declaration of war from Congress, arguing that Mexicans had “shed the blood of our fellow-citizens on our own soil.” By May 13, 1846, both nations officially were at war.