Col. John Brown was an American abolitionist known for his radical opposition to slavery. He believed in using violence to achieve his goals and is best remembered for his raid on Harper's Ferry in 1859, where he attempted to seize a federal armory to arm enslaved people for a rebellion. His actions were part of a larger movement against slavery in the United States. Brown's raid ultimately failed, and he was captured, tried, and executed for treason. His actions and martyrdom made him a symbol of the abolitionist movement, influencing public opinion and contributing to the tensions that led to the American Civil War.