Kagi was admitted to the Nebraska bar that year, but he soon went south to join the abolitionists working to make Kansas a free state, serving under General James H. Lane. Later Kagi enlisted in Aaron Stevens's ("Captain Whipple's") Second Kansas Militia, and met the abolitionist John Brown in Lawrence; another source says they met in Topeka. Deeply influenced by the man, Stevens and Kagi became two of Brown's closest advisers.