Bleeding Kansas, Bloody Kansas, or the Border War was a series of violent civil confrontations in Kansas Territory, and to a lesser extent in western Missouri, between 1854 and 1859. It emerged from a political and ideological debate over the legality of slavery in the proposed state of Kansas.

Free-Staters was the name given to settlers in Kansas Territory during the "Bleeding Kansas" period in the 1850s who opposed the expansion of slavery. The name derives from the term "free state", that is, a U.S. state without slavery. Many of the "free-staters" joined the Jayhawkers in their fight against slavery and to make Kansas a free state.