John Brown was a militant abolitionist who had no problem using violence against those who would enslave another human being. After stirring up trouble during the Bleeding Kansas incidents, Brown hatched and executed a plan to lead an army of freed slaves to fight a war against slavery in Virginia. (Harpers Ferry is now in West Virginia. The state wasn’t created until 1863 by Virginians who were opposed to slavery.)
The first step in the plan – to steal guns from a federal arsenal – didn’t go very well. Most of the group was quickly killed or captured by federal police. John Brown was sentenced to death for treason against the state. He was hung two months later.