Paul Boyer, Todd & Curti’s: The American Nation (Austin: Holt, Rinehart, and Winston, 1995), 348.
With two rival governments in place, conflict was inevitable. Proslavery raiders from Missouri attacked antislavery Kansas settlers, and in May 1856 a proslavery mob of some 700 burned the town of Lawrence, Kansas. In revenge, a group led by abolitionist John Brown attacked a proslavery settlement along Pottawatomie Creek. They dragged five men from their beds and brutally murdered them. The Pottawatomie Massacre enraged southerners, shocked northerners, and sparked more violence in what newspapers began calling "Bleeding Kansas."