Leavenworth, founded in 1854, was the first city incorporated in the territory of Kansas. The city developed south of Fort Leavenworth, which was established as Cantonment Leavenworth in 1827 by Colonel Henry Leavenworth. Its location on the Missouri River attracted refugee African-American slaves in the antebellum years, who were seeking freedom from the slave state of Missouri across the river. Abolition supporters helped them find refuge. In the years before the American Civil War, Leavenworth was a hotbed of anti-slavery and pro-slavery agitation, often leading to open physical confrontations on the street and in public meetings.