John Brown (May 9, 1800 - December 2, 1859) was an American abolitionist who believed in and advocated armed insurrection as the only way to overthrow the institution of slavery in the United States. He first gained attention when he led small groups of volunteers during the Bleeding Kansas crisis of 1856. He was dissatisfied with the pacifism of the organized abolitionist movement: 'These men are all talk. What we need is action--action!' In May 1856, Brown and his supporters killed five supporters of slavery in the Potawatomie massacre, which responded to the sacking of Lawrence by pro-slavery forces. Brown then commanded anti-slavery forces at the Battle of Black Jack (June 2) and the Battle of Osawatomie (August 30, 1856).