Question

Following the Mexican-American War, which issue broke party unity and divided Congress largely along sectional lines?

Answer 1

The issue that becomes the reason of broken trust in the party that leads to the division and unity of the Congress party is the slavery extension in the territories in addition to the Mexico acquired territories.

The whole war started in 1846 and ended in 1848 which come to know as US-Mexican war.

Answer 2

The extension of slavery into territories acquired from mexico.