The Republican Party, however, wanted to repeal the Kansas-Nebraska Act and restore the provision in the Missouri Compromise that prohibited slavery in Kansas. Northern abolitionists began to work under the rules established by Senator Douglas, popular sovereignty, in order to get Kansas admitted as a free state. Both sides of the slavery question sent settlers into the territory of Kansas, in hopes of outnumbering the other side, and electing a territorial legislature and a future state constitution that would either outlaw, or permit slavery.
So called border ruffians raided into Kansas creating violence on both sides of the issue. The most famous was John Brown, a noted abolitionist who felt he was called by God to free the slaves in the South and West. In 1856, a group of border ruffians raided Lawrence, Kansas, an anti-slavery town, burning the buildings and killing one citizen. Five days later, John Brown and his sons and followers raided a settlement along Pottawatomie Creek and ordered five proslavery Kansans executed with a farmers scythe.
The fighting that continued in Kansas became known as Bleeding Kansas and was a sign of the Civil War to come. The popular sovereignty stirred up sectional tensions because it overturned the Missouri Compromise of 1820, which stated that slavery would not expand into any western territory north of Missouris southern border. This made antislavery northerners angry because they wished to stop the spread of slavery in the west, and they felt popular sovereignty was just another tool of the slave power. Their resistance in turn made southerners angry since hey wanted the spread of slavery and felt the Kansas-Nebraska Act had been lawfully passed, therefore northerners couldnt resist it. The act also led to exacerbated sectional tensions between the people of Kansas and Nebraska; for both northerners and southerners moved there to influence the vote and this resulted in riots. These riots further caused discord among antislavery Northerners and proslavery Southerners, who thought Kansas and Nebraska, should be anti or pro slavery, respectively. All these events stirred up and were some of the key cause of the Civil War over slavery.