Border Ruffians were pro-slavery activists from the slave-state of Missouri. From 1854 to 1860 they crossed the state border into Kansas Territory to force the acceptance of slavery there. The name was applied by Free-Staters 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.