While popular nationalism flourished in the United States from the time of the Revolution onward, reflective treatments of what it meant to be, specifically, a “nation” were rarely produced until the Civil War era. Historians have generally treated northern Civil War theorists of the nation as importers of European ideas of organic nationhood to serve conservative and statist purposes. The most notable mid-century theorists—Francis Lieber, Elisha Mulford, Orestes Brownson, John William Draper, Frederick Douglass, and Charles Sumner—were a more diverse set, however. They brought to the subject different theoretical and political assumptions and produced different models of the American nation, and they accommodated their borrowed conceptions to native materials. If their initial aim was to strengthen the authority and unity of the wartime nation, they soon struggled with the multiracial nation that was emerging from the war. The unity they posited in the nation contended with invidious racial, ethnic, and religious distinctions. In the end, Lieber, Brownson, Mulford, and Draper found diversity difficult or impossible to reconcile with their visions of national unity. Only Sumner and Douglass managed to construct models of the nation that were both heterogeneous and united: their postwar views serve as counterpoint to the tortured efforts of the other writers. In the language of current theory, these writers divided over whether the United States was a civic or an ethnic nation, although not all their exclusions and inequalities emanated from an ethnic model of the nation, nor all their inclusions and liberties from a civic one.