Manifest Destiny: Manifest Destiny was the belief popular among Americans in the 19th century that it was their destiny and right to expand westward across North America, spreading democracy and civilization.
Mexican-American War: The Mexican-American War was a conflict fought between Mexico and the United States from 1846 to 1848. It was primarily sparked by border disputes and U.S. expansionist ambitions.
Annexation of Texas: The annexation of Texas refers to when Texas, which had previously been an independent republic after gaining independence from Mexico, joined the United States as its 28th state in 1845. This event played a significant role in escalating tensions between Mexico and the U.S., leading up to the Mexican-American War.