The document summarizes key events from the 1850s that increased tensions between the North and South leading up to the Civil War. The Kansas-Nebraska Act repealed the Missouri Compromise banning slavery north of 36°30', sparking violence in "Bleeding Kansas." The Dred Scott decision found that slaves were not citizens and Congress could not ban slavery in territories. John Brown's raid on Harpers Ferry further alarmed Southerners, while Northerners saw Brown as a martyr. The Republican party was formed to prevent the spread of slavery.