In this provocative interdisciplinary study, Nicholas and Peter Onuf argue that the American Civil War was the first great war between modern nations, emerging from the wreckage of a federal union that was supposed to secure perpetual peace. Situating conceptions of nationhood and war in the broader context of modern history, the authors draw attention to overlooked aspects of liberal thought that stand in tension with the a historical individuals and markets that are so familiar to us today. The liberal conception of the autonomous, rights-bearing individual is the product, not the predicate, of what has actually been a protracted process of development. New ways of historical thinking gave rise to new ideas about the nations that collectively constituted international society; the behavior of sovereign nations in turn provided a liberal model for the reorganization of domestic societies. Changing conceptions of markets provided the impetus for nation-making, as well as for war. In the book's second part the authors show how controversy over trade policy in the early American republic led to irreconcilable ideas about the nature of the union and the relationship between home and world markets. When Southerners embraced the logic of nationhood of their known region and insisted that slavery promoted the wealth and welfare of the civilized world, Northerners held that an expanding continental republic embodied their national aspirations. In this light, the clash between Southern concerns with free markets and Northern concerns about nation-making, each classically liberal in its own way, looms especially large in the sectional tensions that led to the Civil War. The Union and Confederacy went to war as great nations determined to secure their place in the modern, civilized world because they were so much alike. Their war should not be seen as a tragic, inexplicable anomaly in American history. It was, instead, the precedent for subsequent, and even more horrific, conflicts among nations.