In 1855, Redpath moved to the Kansas-Missouri border and reported for a Free Soil newspaper, the "Missouri Democrat", on the dispute over slavery in Kansas Territory. For the next three years, he was active in Kansas affairs, engaging in politics, writing dispatches, securing support in New England for Free Soil settlers, and writing poetry about Kansas. In 1856, he interviewed John Brown just days after the massacre at Pottawatomie Creek. Redpath and Brown shared the same abolitionist views, and he became Brown's most fervent publicist. In addition to his abolitionist views, he also advocated reparations for slavery.