The Border Ruffians were pro-slavery activists from the slave state of Missouri, who in 1854 to 1860 crossed the state border into Kansas Territory to force the acceptance of slavery there. The name was applied by Free-State settlers in Kansas and abolitionists throughout the North. Armed Ruffians interfered in territorial elections, and attacked Free-State settlements. This violence was the origin of the phrase "Bleeding Kansas". The Ruffians contributed to the growing sectional tensions, and helped bring on the American Civil War.