John Brown (May 9, 1800 – December 2, 1859) was a white American abolitionist who advocated and practiced armed insurrection as a means to abolish all slavery. He led the Pottawatomie Massacre in 1856 in Bleeding Kansas and the unsuccessful raid at Harpers Ferry in 1859.
President Abraham Lincoln said he was a "misguided fanatic" and Brown has been called "the most controversial of all 19th-century Americans." His attempt in 1859 to start a liberation movement among enslaved African Americans in Harpers Ferry, Virginia, electrified the nation. He was tried for treason against the state of Virginia and was hanged, but his behavior at the trial seemed heroic to millions of Americans.
Southerners alleged that his rebellion was the tip of the abolitionist iceberg and represented the wishes of the Republican Party. Historians agree that the Harpers Ferry raid in 1859 escalated tensions that a year later led to secession and the American Civil War. http://en.wikipedia.org/wiki/John_Brown_(abolitionist)