The U.S. state of Kansas came into being as a federal territory in 1854 as a result of the Kansas-Nebraska Act. Although Kansas lay north of the 36-30' line of latitude dividing free soil from areas where slavery was permitted, the K-N Act allowed popular sovereignty to decide the status of the two new territories being formed from previously unorganized territory. Southerners interpreted this as a chance to balance an obviously northern, free soil Nebraska Territory with a pro-slavery Kansas Territory.

In 1856, an election was held in an attempt to form a government in Kansas. 1500 men were registered to vote, but 6307 actually did, many from slave state Missouri. As a result of this, a fraudulent pro-slavery government was formed at Shawnee Mission. As a reaction, abolitionist forces, who probably should have won a fair election, formed an extra-legal free soil government at Topeka. Conflicts emerged very quickly, particularly since both governments were attempting to grant the same parcels of federal land to settlers.

On 21 May 1856, pro-slavery forces instigated a bloody brawl/battle at Lawrence between pro- and anti-slavery supporters. No one was killed in this battle, but an abolitionist legend heard a rumor that five abolitionists were killed, and decided to seek vengeance, since he himself felt that he was God's emissary on Earth with the sole purpose of ending slavery in America.

On 24 May 1856, John Brown and seven other men, including four of his sons and his son-in-law, attacked at Pottawatomie Creek, selected five pro-slavery whites, and, with their wives and children watching, butchered them with broadswords. The "Pottawatomie Creek Massacre," as it became known, instigated an internal civil war in Kansas, which was only settled by federal troops and the replacement of the territorial governor.

Although Kansas would apply for statehood as early as 1859, as a free state, it would not actually be admitted until 1863, after 11 of the 15 slave states had left to form the Confederate States of America.