Recently, the study of civil wars has attracted more and more attention from scholars of international relations. Using a computer simulation called EARTH (Exploring Alternative Realpolitik THeses) that not only simulates a realist world, but also includes civil wars, the author explores what aspects of a realist world are associated with the onset of civil war. Although features of a realist world are not the dominate factors in accounting for civil wars, the loss of territory that accompanies losing interstate wars does influence the chances of states undergoing civil war.