Academics who study the scourge of civil war tend to see the engineers of violence as rational actors engaging in carefully calculated cost-benefit analyses. Petersen fights that line of thought. He finds the conventional analysis inadequate and believes it leads to wrong-headed explanations of why the international community’s efforts to mitigate civil wars often fall short. Having spent years trying to understand the violence in the former Yugoslavia, he insists that those who have no interest in peace skillfully exploit fear, anger over lost status, and the desire for revenge generated by the bloodletting. International peacemakers, operating from conventional rational-choice calculations that rely on material incentives, do not understand the asymmetric disadvantage they are at when the rawness of emotions is used to thwart their efforts. Petersen not only presents rigorous, detailed case studies of the intervention in Kosovo and other Balkan interventions; he also demonstrates the similarities between them and other cases of interethnic conflict, such as in Rwanda and Northern Ireland.