Term applied to a period of civil unrest (1854–59) between proslavery and antislavery advocates for control of the new Kansas Territory.
Under the doctrine of popular sovereignty , antislavery emigrants from the North clashed with armed proslavery groups from Missouri. In 1856 a proslavery raid and burning of a hotel and newspaper in Lawrence were followed by several murders instigated by antislavery radicals under John Brown . Sporadic battles continued until Kansas was admitted to the Union as a free state in 1861.