The Pottawatomie Rifles was a group of about one hundred abolitionist (or free state) Kansas settlers of Franklin and Anderson counties, both of which are along the Pottawatomie Creek. The band was formed in the fall of 1855, during the Bloody Kansas period, as an armed militia to counter growing proslavery presence (an influx of men known as Border Ruffians) in the area and along the Missouri border.
Led by John Brown's son, John Brown Jr., men from the Pottawatomie Rifles took part in much of the violence known as Bleeding Kansas, including the Battle of Osawatomie and the Pottawatomie massacre. Although John Brown, who was famous for his own raids, such as the raid on Harpers Ferry, frequently accompanied his son, he was not officially a member of the group.
The Pottawatomie Massacre took place between the night of May 24 and the morning of May 25, 1856. In revenge for the sacking of Lawrence, Kansas by pro-slavery forces such as Border Ruffians, in which a sheriff-led mob trashed newspaper offices and a hotel and killed two men, John Brown and various abolitionist settlers and abolitionist groups, most of whom were Pottawatomie Rifles, killed five pro-slavery settlers. The incident occurred north of Pottawatomie Creek, near its junction to Mosquito Creek, in Franklin County, Kansas. Some sources cite that John Brown Sr. led the massacre, beginning from May 22, in a private expedition which consisted of his sons Oliver, Watson, Owen, and Frederick, his son-in-law Henry Thompson, and two men named James Townsley and Thomas Winer who were transporting the men in their wagons, but not his son John Brown Jr.