worse in rural areas, where denouncers are more visible. If denunciation and violence take place, the victim's kin can either refrain from retaliating or choose to retaliate, depending on the risks of doing so given the level of control of their side in that given territory. When that level is balanced for both sides, the equilibrium can result in either indiscriminate violence or no violence at all due to mutual deterrence. This approach to violence as a joint process, where violence only takes place when civilians and political powers cooperate given their interests and cost-benefits calculations, lets the author to develop a model that predicts on one hand the likelihood of violence in a given area; on the other, it clarifies the moral hazard problem political contenders confront because the abundance of informers is inversely proportional to their usefulness, as we saw above. And, to sum up, that parsimonious model surprise readers because it is able to predict levels (variation) of violence from a micro approach. The evidence To run a convincing empirical test of that model, the author collected regional data of the Greek Civil War, and next to two thirds of violence variation is successfully predicted by the model. And additionally, to test its validity outside the Greek sample, the model is successfully confronted with a large variety of historical and anecdotal accounts about civil wars around the world. Those findings, both theoretical and empirical, have several significant implications. One of them is that violence in any civil war is a function of civilians’ previous feuds among them and the distribution and degree of control of the contenders over the territory in conflict. The former is given before the war, but it only takes the shape of violence jointly to the latter, namely when sovereignty is fragmented by competing powers. These findings also explain why contenders will prefer to use selective to indiscriminate violence, and when the latter will take place. The behavioural microfoundations established in the game-theoretical model, and the principal-agent dilemmas the players confront constantly, let to this work to provide an answer to violent outcomes based on incentives and rational behaviour, instead of on gut reactions and irrational impulses. Open extensions Leaving apart those implications, the argument of the manuscript arises some questions that are partially answered by the author, specifically if the model is applicable both to ethnic and non-ethnic violence during civil wars,