Missouri Compromise: An agreement passed by Congress in 1820 that temporarily resolved tensions over the expansion of slavery by admitting Missouri as a slave state and Maine as a free state.
Popular Sovereignty: A principle that allowed residents of a territory to decide whether it would be admitted as a free or slave state through voting.
John Brown: An abolitionist who played a significant role in Bleeding Kansas, leading attacks against pro-slavery settlers and initiating conflicts during this period.