Civil wars are an enduring feature in history. The crisis and collapse of unified political authority over a territory attracted the attention of ancient Greek and Roman historians just as much as that of present day’s social scientists. Civil wars vary in their causes, severity of violence, length, and outcomes. However, overall, this type of conflict represents, in terms of numbers and lethality, the dominant form of contemporary warfare. This entry discusses the nature of civil war, from the observations of historians in ancient Greece and Rome to the findings of contemporary scholars, with detailed attention to the economic, social, and cultural causes of intrastate conflicts. Next, an analysis of the dynamics of violence in civil wars leads to further observations of the ways in ...