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.
Notably, only a few of the Border Ruffians actually owned slaves; most were too poor. What motivated them was hatred of Yankees and abolitionists, and fear of free blacks living nearby. The Ruffians were driven by the rhetoric of leaders such as U.S. Senator David Rice Atchison of Missouri, who called Northerners "negro thieves" and "abolitionist tyrants." He encouraged Missourians to defend their institution "with the bayonet and with blood" and, if necessary, "to kill every God-damned abolitionist in the district."
Ironically, the bulk of Free-State men in Kansas were not abolitionists, and opposed the presence of both free blacks and slaves. "We want no slaves and we want no Negroes" was the prevailing sentiment reported by an abolitionist in 1854. 
Additionally, the presence of bands of both Kansan and Missourian combatants in the area made it difficult for families on the border to remain neutral.
The Border Ruffians in "Bleeding Kansas" 
Kansas Territory was created by the Kansas-Nebraska Act of 1854. The Act repealed the previous Federal prohibition on slavery in that area. Instead, the locally elected territorial legislature would decide.
At this time, many (probably most) of the settlers in Kansas opposed slavery. However, slavery advocates determined to have their way regardless. When elections were held in Kansas Territory, bands of armed Ruffians seized polling places, prevented Free-State men from voting, and cast votes themselves (illegally, since they were Missourians).
On 29 November 1854, Border Ruffians elected a pro-slavery territorial representative to Congress. On 30 March 1855, the Ruffians elected a pro-slavery legislature.
Despite these measures, far more Free-State settlers moved to Kansas than pro-slavery settlers. In 1857, pro-slavery settlers in Kansas proposed the Lecompton Constitution for the future state of Kansas. The Ruffians tried to get the Lecompton Constitution adopted with additional fraud and violence, but by then there were too many Free-Staters there.
The Border Ruffians also engaged in general violence against Free-State settlements. They burned farms and sometimes murdered Free-State men.
Most notoriously, the Ruffians twice attacked Lawrence, Kansas, the Free-State capital. On 1 December, 1855, a small army of mainly Border Ruffians laid siege to Lawrence, but were driven off. (This was the nearly bloodless climax to the "Wakarusa War".)
Free-State settlers sometimes struck back. Free-State irregulars (known as Jayhawkers, Redlegs, or Redleggers) attacked pro-slavery settlers and suspected Ruffian sympathizers. Most notoriously, abolitionist fanatic John Brown killed five pro-slavery men at Osawatomie.
The Border Ruffians in the Civil War 
During the Civil War, the violence in this area not only continued, but escalated tremendously. Many of the former Ruffians became pro-Confederate guerrillas. They operated in western Missouri, sometimes raiding into Kansas, and Union forces campaigned to suppress them. Farms were burned and looted. Suspected guerrillas were killed; guerrillas killed Union sympathizers and suspected informers. (See Bushwhacker.)
Many of the Union troops involved were Kansas Jayhawkers, and had deep grudges against Missourians. Jayhawkers destroyed several towns in Missouri, such as Osceola. The destruction of Osceola is depicted in the movie The Outlaw Josey Wales.
See also 
- "Border Ruffians - KS-Cyclopedia - 1912". 2002. Retrieved 2007-11-19.
- "Bleeding Kansas: Mid 1850s - Precursor to the Civil War". www.u-s-history.com. 2002-2005. Retrieved 2007-11-19.
- Furnas, J. C. The Road To Harpers Ferry 1959, p.?
- "Bleeding Kansas". Fort Scott National Historic Site. Retrieved 2007-11-19. Unknown parameter
- Bad Blood, the Border War that Triggered the Civil War DVD documentary. Kansas City MO: Kansas City Public Television (KCPT) and Wide Awake Films. 2007. ISBN 0-9777261-4-2