who was the person who killed all of the slave owners and helped with the underground railroad?

Answer 1

Osawatamie Brown! Also known as John Brown. The massacre on Pottawattame, KS was not slave owners, but those who moved to the territory that were pro-slavery. At this time the Missouri Compromise allowed each state to select slavery or not based on votes. John Brown moved him and his sons to Kansas to swing the vote to a non-slave state. John Brown didn't himself kill the pro-slavers, but approved of the massacre.

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Answer 2

Are you referring to John Brown?