The Compromise of 1850 was a set of resolutions designed to persuade both northern and southern states to make concessions about the expansion of slavery in order to avoid civil war. After years of simmering tension, disagreements between the northern and southern states had erupted as a result of the Mexican-American War (1846–1848). The acquisition of thousands of miles of western territory from Mexico raised questions about the expansion of slavery. The controversy grew especially intense in the U.S. Congress, where antislavery and proslavery factions used increasingly hostile language and threatened to break up the Union. Undertaking the difficult challenge of calming the situation was Senator Henry Clay, a veteran Kentucky legislator and three-time presidential nominee.