History of South America

Why did the Mexicans attack maericans first in war of 1846?

Mexico did not attack the United States first in the Mexican-American War. In fact, the United States declared war on Mexico in May 1846. There were a number of factors that led to the war, including the annexation of Texas by the United States in 1845, a dispute over the border between Texas and Mexico, and the desire of some Americans to expand the territory of the United States into Mexico.