Should Kansas be admitted into the Union as a free state or a slave state? That’s the question settlers faced in a vote following the Kansas-Nebraska Act of 1854. The vote over the status of the new territory caused both opponents and supporters of slavery to descend upon the region to sway the decision. In the period known as Bleeding Kansas, these groups then engaged in a series of brutal confrontations that ultimately contributed to the start of the Civil War.

“Bleeding Kansas really radicalizes white northerners and white southerners against each other in the 1850s and causes them to distrust the other side,” says Nicole Etcheson, author of Bleeding Kansas: Contested Liberty in the Civil War Era and a history professor at Ball State University. “These tensions have been around for a long time, but they come to a critical mass in the 1850s and all the things that go on in the Kansas territory from 1854 to 1861 just turn people against each other.”

The Kansas-Nebraska Act—formally known as “An Act to Organize the Territories of Nebraska and Kansas”—repealed the Missouri Compromise of 1820, which had banned slavery north of the 36º30’ latitude in the Louisiana territories, with the exception of Missouri. Introduced in January 1854 by Senator Stephen Douglas of Illinois, the Kansas-Nebraska Act gave both of the new states the right to decide whether or not to permit slavery when it joined the Union. This choice reignited the dispute about the fate of slavery in the United States.

Douglas was a champion of Manifest Destiny, or the belief that God had willed the United States toward rapid expansion, even if doing so drove Indigenous groups from their homelands. After sawmill operator James W. Marshall found gold in California, interest in Westward expansion intensified, with plans for a transcontinental railroad from east to west.

Douglas wanted Chicago to be the home of the eastern terminal, but for that to happen, the Nebraska territory had to be organized. Needing the Southern vote to achieve his goal, Douglas presented the Kansas-Nebraska Act, which passed on May 30, 1854.

The legislation infuriated opponents of slavery because the Missouri Compromise would have prohibited human bondage in both territories, which were north of the 36º30’ latitude line. Determined to stop the spread of slavery, they headed to Kansas with the goal of winning the first election after the Kansas-Nebraska Act’s passage. About 1,200 New Englanders headed to the territory with support from efforts like the New England Emigrant Aid Company established by U.S. Representative Eli Thayer of Massachusetts. But most of the Northern settlers came from the Midwest.

Thousands of slavery supporters, many of them Missourians, traveled to Kansas, too, and the bloodshed that followed gave rise to the term “Bleeding Kansas.” Historians have attributed violence in Kansas and Missouri during this era to the competing governments that formed in the region, fights over land, and fraudulent elections. Three major factions became embroiled in these conflicts: pro-slavery forces, abolitionists, and Free-Staters, also known as free soilers, who opposed slavery’s expansion.

“At the same time that white Southerners are coming out to make Kansas a slave state, some of those people are slaveholders themselves,” says Kristen Epps, an associate professor of history at Kansas State University and editor of Kansas History: A Journal of the Central Plains. “So you have enslaved African Americans coming out as well. Of course, they're wanting freedom, right? They don't want to spread slavery, they don't want to be enslaved themselves and have their children be enslaved.”

Thousands of pro-slavery settlers, known as “Border Ruffians” because so many streamed in from neighboring Missouri, voted in a proslavery congressional delegate in November 1854. Registered voters accounted for just half the ballots. When another election took place in March 1855 to select members of the territorial legislature, the Ruffians once again triumphed. That time around, registered voters cast fewer than half the ballots.

“The elections were a mess,” Etcheson says. “There was real election fraud in Kansas in 1854 up through like 1858 in these territorial elections. The Missourians came over into Kansas and they voted. ​​The census—they’d done a count in early 1855—they knew how many people were in Kansas territory. They knew that there were less than 3,000 adult white men eligible to vote in the territory, but the slavery candidates win with…twice as many votes possible.”

With Kansas in their control, the proslavery state legislature implemented laws that imposed stringent penalties for individuals who spoke out against slaveholding, including hard labor or death for anyone who helped enslaved fugitives. In response to these laws, the Northerners established a Free State legislature in Topeka, resulting in Kansas housing two competing governments. President Franklin Pierce only acknowledged the fraudulent pro-slavery government.

Although Kansas became the national epicenter of the slavery question, most settlers cared more about land ownership than the issue of human bondage. “Free soilers are looking to limit slavery’s expansion, not necessarily for moral or ethical reasons, but really more as a way to limit competition from free Black labor and from slave labor,” Epps says.

As the Free Staters, abolitionists and proslavery forces fought for control of Kansas, more outbreaks of violence occurred, including shootouts between the factions, guerilla warfare and  the imprisonment of Free-Staters by the federal government, Etcheson says.

These incidents prompted a congressional committee in April 1856 to head to the new home of the pro-slavery government in Lecompton, Kansas. The committee found evidence of widespread election fraud in the territory and determined that most settlers supported a free Kansas. The federal government, however, ignored these findings, and violence continued.

After proslavery forces burned the Free State Hotel in Lawrence on May 21, 1856, among other offenses, abolitionist John Brown and his four sons infamously massacred five slavery supporters at Pottawatomie Creek.

“John Brown is not a typical Free-Stater,” Etcheson says. “He shows up in Kansas late. He doesn't participate in creating the Free State movement. He is not part of this extra legal government. He doesn't much believe in voting anyway. He’s a loose cannon.”

Free-State leaders such as Charles Robinson, an abolitionist and Massachusetts doctor who settled in Kansas, feared the use of violence among his faction would lead the federal government to squash the movement, so Free-Staters initially tried to engage in nonviolent resistance, according to Etcheson. Brown did not represent this ideology with his egregious acts of violence.

Even Congress was not spared from the viciousness associated with Bleeding Kansas. After giving a speech called “The Crime Against Kansas” that called out proslavery senators, including Andrew Butler of South Carolina, Senator Charles Sumner of Massachussetss was savagely caned by Butler's nephew on May 22, 1856.

“It takes him a while to recover and he's not quite himself for a few years after that,” Epps says.

In the summer of 1856, more violence erupted when roughly 30 slavery supporters settled near Fort Scott. These settlers arrived from South Carolina with purported help from the Southern Emigrant Aid Society and were thought to belong to the Dark Lantern Societies. These groups were notorious for tormenting Free-Staters to get them to leave Kansas.

When John W. Geary became the new territorial governor in September 1856, outbreaks of brutality in Kansas finally waned.

“John Geary had been mayor of San Francisco during the gold rush,” Etcheson said. “He's this big, tough guy, and he is sent out explicitly with instructions to restore order in Kansas. He comes in and says, ‘I don't care who's running around the territory shooting at each other. They're going to stop. I don't care if they're pro-slavery. I don't care if they're free state.’”

Because Geary was impartial, Etcheson says, the army trusted him and worked to drive out bands of armed vigilantes from the territory, including John Brown, who went on to raid the  U.S. arsenal at Harpers Ferry, Virginia, with the aim of starting a slave rebellion in the South.

Despite new territorial leadership, on May 19, 1858, Border Ruffians captured 11 Free-Staters, killing five in a final spasm of violence that became known as the Marais des Cygnes massacre.

With the support of James Buchanan, who succeeded Pierce as president in 1857, the proslavery forces attempted to institute a proslavery constitution and get Kansas admitted to the Union as a slave state.

But Free Staters and Northern Democrats such as Douglas, whose Kansas-Nebraska Act caused the unrest in the region in the first place, objected, claiming that there had never been popular sovereignty in Kansas due to widespread election fraud. After new territorial governors oversaw what what regarded as a fair election, Free-Staters finally won control of the legislature.

“By 1858, you’ve got the turning point where the pro-slavery party realizes it's over,” Etcheson says. “They've got federal territorial officials who aren't putting up with them anymore. They know this is not going to work.”

In July 1859, Kansas drafted a free state constitution to join the Union—but not without objections from the pro-slavery faction, who later seceded. Only then did Kansas officially become a free state on January 29, 1861. Altogether, 55 people were killed in the territory from 1854 to 1861. The violence served to deepen the North-South divide on slavery, making a civil war imminent.

Epps points out that the clashes reflected a heated battle not only over slavery as a concept—but over laws that would determine people's very lives.

"There are enslaved people living in Kansas territory at the time that are living on the Kansas-Missouri border," Epps says. "So this is more than just this kind of abstract debate about the morality of this system. It's actually a conversation that grows so heated because it does have these really tangible implications.”