Brown lived mostly in Springfield, Massachusetts before moving to the Kansas Territory. This would later become the state of Kansas in 1861. Several of his sons were already living there. Brown's sons wanted his help to fight people from Missouri. The people in Missouri wanted slavery to be legal in Kansas. On May 24, 1856, Brown and his sons killed five people in Kansas who wanted slavery to be legal. They dragged the people out of their homes and killed them with swords. This came to be known as the Pottawatomie massacre. Many people in Kansas were shocked and upset about this. More violent things happened after this. This was the beginning of the period in the Kansas Territory known as Bleeding Kansas. Before leaving Kansas, Brown and his followers were attacked at the Battle of Osawatomie on August 30, 1856. His son Frederick was killed there.