The Wilmot Proviso, as it was called, was passed by the House of Representatives but rejected by the Senate. Senator John C. Calhoun of South Carolina led other members of the Senate against the amendment because they supported the extension of slavery through the South. Those who supported the amendment feared the political power that the South was gaining. For the most part, they opposed slavery on moral grounds. It was evident that some states in the South were willing to secede rather than to accept anything like the Wilmot Proviso. This amendment was to push the issue of slavery to the forefront of American politics from 1847 to the beginning of the Civil War. The Mexican-American War (1846–1848) ended with huge gains in territory for
