In 1854, the Missouri Compromise, which had restricted the expansion of Slavery in the United States, was done away with by the Kansas–Nebraska Act. Based on the doctrine of popular sovereignty, the federal government allowed the issue of slavery to be decided by those settling the Kansas Territory. By popular vote the people who lived there would decide whether Kansas would become a "slave-state" or be a "free-state" (free of slavery). Pro-slavery Missourians, Free-Staters and abolitionists all poured into Kansas. Soon, the different sides held their own elections and set up two opposing territorial governments. In May 1856, a drunken mob of pro-slavers sacked the town of Lawrence. Brown was enraged at this and wanted vengeance.