What was "popular sovereignty"? Did it succeed in Kansas?

In 1854, Congress again confronted the issue of slavery in the West when the Nebraska Territory was opened to settlement. This vast land, stretching north to the Canadian border, was large enough to become several states. Stephen Douglas successfully urged that the issue of slavery in these new territories be decided by popular sovereignty. This meant settlers could vote for or against slavery. In theory, popular sovereignty would reduce the controversy over slavery; instead of allowing arguments over slavery to tear apart the U.S. Congress, Americans would have a series of smaller debates in each new Western state. These smaller debates might become heated, but they would not split the nation in two. The Kansas-Nebraska Act (1854) opened these new territories to popular sovereignty.

In practice, popular sovereignty proved a disaster, especially in the Kansas Territory. Both pro-slavery and antislavery forces streamed into the new territory so they could gain a majority when Kansans wrote a state constitution and applied to join the United States. Elections in Kansas became very angry and were marred by widespread voter fraud. Two rival governments claimed the right to rule over Kansas--a pro-slavery government in Lecompton, and a free state government in Topeka. Violence also erupted in Kansas: pro-slavery forces burned parts of the free state stronghold of Lawrence in 1856, and antislavery settler John Brown led a raid near Pottawotomie Creek, in which he and his followers murdered five pro-slavery settlers.

Bleeding Kansas, as Americans called it, demonstrated that popular sovereignty, far from minimizing the conflict over slavery, was transforming the debate over slavery into a war over slavery. Popular sovereignty also failed to remove the controversy over slavery from the halls of Congress. As events in Kansas turned increasingly violent, Senator Charles Sumner of Massachusetts delivered an antislavery speech in which he harshly criticized Senator Andrew Butler of South Carolina. Upon hearing of this speech, Representative Preston Brooks (another South Carolinian, and Butler's cousin) stormed into the Senate chamber and beat Sumner savagely with his cane. Sumner was so badly injured that he required three years to recover fully from the beating and return to his position as the Senate's leading opponent of slavery. While many Americans were shocked by Brooks' attack, many white Southerners cheered, sending Brooks dozens of new canes to replace the one he had splintered while clubbing Senator Sumner. The political controversy in Kansas continued for years, until Kansas was finally added to the Union as a free state in January 1861.