The election of 1856 saw the emergence of the Republican Party and the political realignment that produced the Civil War. While these events are often interpreted as a defensive response to proslavery aggression, in Kansas and elsewhere, this essay emphasizes the extent to which they reflected the victory of antislavery agitation in national politics. The Republican campaign of John C. Fremont was built around a populist assault on the Slave Power as an entrenched elite: politicians and activists from Henry Wilson to Frederick Douglass celebrated mass mobilization against corrupt legal authority, arguing that a sovereign popular will could not be constrained by cautious appeals to "law and order." This consciously revolutionary campaign had even more revolutionary implications. Although they were defeated on election day, Republicans made themselves the dominant party in the North, transforming national politics into an existential contest over the future of slavery.