Purpose – The forced rural–urban migration in Colombia is a phenomenon that could be seen as the collateral damage of an armed conflict that takes place mainly in rural areas. Nevertheless, there is a significant percentage of cases in which the main reason to flee is a direct threat by an armed actor. This chapter proposes a possible reason why an illegal armed group displaces population from rural to urban areas.Design/methodology/approach – A two-stage game theoretical model is considered, in which the central government struggles over the control of a region with the insurgents. In the first stage, rebels have the choice of forcing a proportion of peasants out of the rural areas or not. In the second stage, both players choose the level of military expenditure.Findings – It is found that, under certain circumstances, the displaced population could be used by the insurgents as a means to deter the central government from fighting. This model predicts that the larger the value rebels attached to the contested region, the higher the proportion of forced migrants. It is also consistent with the idea that if the central government can commit to warfare, then forced migration will be useless for rebels.Originality/value – This chapter explores a new rationale for forced displacement which consists in lowering government's incentives to fight for a region, by reducing the remaining population which in turn reduces income for the government.