January 29, 1850: Senator Henry Clay of Kentucky introduced the Compromise of 1850, a set of resolutions aimed at diffusing the sectional crisis over the expansion of slavery into newly acquired territories following the Mexican-American War. The compromise was passed in September 1850.
May 30, 1854: The Kansas-Nebraska Act became law. Designed by Senator Stephen Douglas of Illinois, the Act repealed the geographical boundaries set in place by the Missouri Compromise of 1820 by allowing settlers in the new territories of Kansas and Nebraska to decide through “popular sovereignty” whether to permit or prohibit slavery.
May 22, 1856: Just days after delivering his inflammatory “Crime Against Kansas” speech in opposition to slavery in the Kansas Territory, Senator Charles Sumner of Massachusetts was attacked in the Senate Chamber by Representative Preston Brooks of South Carolina, who severely beat the senator with a cane.
January 4, 1859: The Senate moved to its new chamber in the newly expanded Capitol.
December 5, 1859: The Senate convened for the 36th Congress.
December 14, 1859: The Senate launched an investigation into the attack on Harper's Ferry.