or if the model is efficient predicting the sort and intensity of violence when some complexity is added, namely more than two players (i.e. Colombian conflict), non-unitary players (adding some proxy of ‘internal cohesion’ to the apparatus of both contenders, since soldiers or militias are at the same time agents of one power and individuals with their own private feuds, grievances and family to defend; and they can commit violence or avoid it even when the rational strategy of the unitary contender is the opposite). Additionally, since the temporal dynamics of the civil war are just roughly outlined, one can ask if frontiers between the five defined categories of controlled areas would be blurred depending on the kind of military strategies that take place. Mutual blitzkriegs and positional wars in a vast, underpopulated territory can make very difficult for players to know the real degree of control that both powers have in any given territory, especially in those considered as “3” in Kalyvas’ categorization (see figure). In other words, trench wars tend to create stable areas, and thus, concentrated violence in disputed regions. The logic of violence in these wars (also called Conventional civil wars) is different from that described by Kalyvas, which applies to Irregular civil wars. Conversely, military strategies that rely in quick movements and constant interchange of lands tend to spread violence across the territory. Reception The book was favorably reviewed by Jóhanna Kristín Birnir (of the University of Maryland), who wrote, "this book combines much of the best that comparative politics has to offer: conceptually clear and rigorous theorizing based on insights from extensive field work, and tested in a methodologically solid fashion on a wealth of quantitative and qualitative data. The conclusions constitute a major contribution to our understanding of violence in civil conflict." Laia Balcells praised the book for its contributions to the political violence and civil war literatures. In criticisms of the book, she argues that Kalyvas's formal model only covers the tactical dimension of civil war, but not the strategic dimension. She also argues that armed groups in full control of territory should have an incentive to gather information about civilians, which should prompt violence. Related references Laia Balcells, "Rivalry and Revenge: Violence against Civilians in Conventional Civil Wars," International Studies Quarterly, Vol. 54, No. 2 (June 2010), pp. 291–313. Laia Balcells, "Continuation of Politics by Two Means: Direct and Indirect Violence