John Brown was a radical abolitionist who believed in the violent overthrow of the slavery system.

Brown and his sons led attacks on pro-slavery residents. Justifying his actions as the will of God, Brown soon became a hero in the eyes of Northern extremists and was quick to capitalize on his growing reputation.

He had succeeded in enlisting a small “army” of insurrectionists whose mission was to foment rebellion among the slaves

In 1859, Brown and 21 of his followers attacked and occupied the federal arsenal in Harpers Ferry.

Their goal was to capture supplies and use them to arm a slave rebellion. Brown was captured during the raid and later hanged, but not before becoming an anti-slavery icon

http://www.history.com/topics/black-history/underground-railroad
http://history.howstuffworks.com/historical-events/underground-railroad.htm
http://thegoldenpathway.blogspot.com/2011/01/code-words-were-essential-in-conducting.html