the pottawatomie massacre happened on the night of may 24, 1856. john brown and a number of volunteer free-staters attacked and murdered five men in a small settlement on the pottawatomie creek near osawatomie, kansas. the killings were particularly brutal. one by one, settlers were dragged from their homes and hacked to death with broadswords and shot. the victims were pro-slavery, but were not slave owners themselves. the murders were in response to pro-slavery missouri border ruffians who burned and looted lawrence, kansas three days earlier. it happened just two days after the caning of charles sumner, the senator from massachusetts on the floor of the united states senate. the pottawatomie massacre was one of the many bloody episodes in kansas preceding the american civil war. it marked the beginning of the period called bleeding kansas.