This dissertation analyzes how Republican leaders and intellectuals embraced a new understanding of their polity as they scrambled to save it during the Civil War. An adequate solution to the problem of secession and slavery required a much broader reconceptualization of the political system as a whole. But most Republicans did not see it this way at the time. They sincerely believed that the conservative and revolutionary elements of their agenda were not only compatible but complimentary, a belief that arose almost automatically from their perception of the “slavepower” as an external threat to their cherished order, rather than an intrinsic part of it. Far from inhibiting the Republicans, this illusion united their hopes and fears into a resolute sense of purpose. Only gradually, in responding to one emergency after another, did Republicans begin to accept that the moral and practical imperatives of the war entailed a fundamental departure from the constitutional system they were trying to preserve, a departure that went beyond any particular issue to redefine the very meaning of free government. My goal is to show how the key concepts in the antebellum political vocabulary – liberty, equality, state(s), and citizen – were refashioned in the violent process by which an entirely new conception of the Republic emerged from the failure of the old.