The 1850s incidents and time period that became known as “Bleeding Kansas” grew out of the 1854 Kansas-Nebraska Act that governed the legality of slavery in the Western States. A reaction to the Missouri Compromise, the Act gave more leeway for each territory to decide the legality of slavery. This freedom of choice, called “popular sovereignty,” emphasized the territories’ rights over federal standardization, which foreshadowed the states’ rights issue emphasized in the Civil War.
Kansas became the primary state in which the battles over slavery were fought, both legally and physically. Two separate legislatures were established. People swarmed to the state in support of both sides. Many new settlers brought workers whom they insisted could be legally enslaved. Abolitionists and opponents of the expansion of slavery not only verbally confronted the pro-slavery residents, but even attacked them and destroyed their property. These conflicts reached a peak with incidents at Pottawotamie Creek, led by the ardent abolitionist John Brown, and at Marais de Cynges. The level of violence and the inability of the two sides to compromise peacefully in the 1850s foreshadowed the nationwide violent conflict of the 1860s.