"Bleeding Kansas" refers to a series of violent conflicts that occurred between 1854 and 1859 in the Kansas Territory. This turmoil arose from the debate over whether Kansas would enter the Union as a free or slave state, following the passage of the Kansas-Nebraska Act. Pro-slavery and anti-slavery settlers rushed into the territory to influence the decision, leading to clashes and bloodshed. The violence was marked by events such as the Sack of Lawrence and the actions of figures like John Brown, an abolitionist who believed in using force to combat slavery. Ultimately, "Bleeding Kansas" highlighted the deep divisions in the United States over slavery, foreshadowing the Civil War.