Humanities › History & Culture American History Lesson: Bleeding Kansas When the Fight Over Slavery Became Violent Share Flipboard Email Print MPI/Getty Images History & Culture Military History Battles & Wars Key Figures Arms & Weapons Naval Battles & Warships Aerial Battles & Aircraft Civil War French Revolution Vietnam War World War I World War II American History African American History African History Ancient History and Culture Asian History European History Genealogy Inventions Latin American History Medieval & Renaissance History The 20th Century Women's History View More By Martin Kelly History Expert M.A., History, University of Florida B.A., History, University of Florida Martin Kelly, M.A., is a history teacher and curriculum developer. He is the author of "The Everything American Presidents Book" and "Colonial Life: Government." our editorial process Martin Kelly Updated February 01, 2019 Bleeding Kansas refers to the time between 1854 and 1859 when the Kansas territory was the site of much violence over whether the territory would be free or slave-owned. This time period was also known as Bloody Kansas or the Border War. A small and bloody civil war over slavery, Bleeding Kansas made its mark on American history by setting the scene for the American Civil War around 5 years later. During the Civil War, Kansas had the highest rate of casualties of all Union states due to its pre-existing division of slavery. The Beginning The Kansas-Nebraska Act of 1854 led to Bleeding Kansas as it allowed the territory of Kansas to decide for itself whether it would be free or slave-owned, a situation known as popular sovereignty. With the passage of the act, thousands of pro- and anti-slavery supporters flooded the state. Free-state proponents from the North came into Kansas to sway the decision, while "border ruffians" crossed over from the South to advocate for the pro-slavery side. Each side organized into associations and armed guerilla bands. Violent clashes soon occurred. Wakarusa War The Wakarusa War occurred in 1855 and was galvanized when free-state advocate Charles Dow was murdered by pro-slavery settler Franklin N. Coleman. Tensions escalated, which led to pro-slavery forces besieging Lawrence, a known staunch free-state town. The governor was able to prevent an attack by negotiating peace treaties. The only casualty was when anti-slavery Thomas Barber was killed while defending Lawrence. Sack of Lawrence The Sack of Lawrence took place on May 21, 1856, when pro-slavery groups ransacked Lawrence, Kansas. Pro-slavery border ruffians wreaked havoc and burned a hotel, the governor's home, and two abolitionist newspaper offices in order to quench abolitionism in this town. The Sack of Lawrence even led to violence in Congress. One of the most publicized events that occurred in Bleeding Kansas was when one day after the Sack of Lawrence, violence occurred on the floor of the U.S. Senate. Congressman Preston Brooks of South Carolina attacked abolitionist Senator Charles Sumner of Massachusetts with a cane after Sumner spoke out against Southerners responsible for violence in Kansas. Pottawatomie Massacre The Pottawatomie Massacre occurred on May 25, 1856, in retaliation of the Sack of Lawrence. An anti-slavery group led by John Brown killed five men associated with the Franklin County Court in a pro-slavery settlement by Pottawatomie Creek. Brown's controversial actions sparked retaliatory attacks and thus counter-attacks, causing the bloodiest period of Bleeding Kansas. Policy Several constitutions for the future state of Kansas were created, some pro- and some anti-slavery. The Lecompton Constitution was the most important pro-slavery Constitution. President James Buchanan actually wanted it to be ratified. However, the Constitution died. Kansas eventually entered the Union in 1861 as a free state.