Third-Party Intervention and the Civil War Process

Abstract What effect do third parties have on the evolution of civil wars? The authors argue that intervention by third parties is central to the civil war process, a process that is characterized by the duration of hostilities and the type of outcome. The authors examine empirically the effect of third-party intervention into civil wars during the period 1816—1997, using the event history framework of competing risks. From the perspective of competing risks, as a civil war endures, it is at risk of experiencing a transition to one of three civil war outcomes in our sample: military victory by the government, military victory by the opposition group, and negotiated settlement. The competing risks approach provides considerably better leverage on the dynamic qualities of civil wars and, in particular, the influence of interventions by third parties. The analysis suggests that third-party interventions can be decisive in the evolution of civil wars and that third-party interventions have a different effect on the duration than different civil war outcomes. The results show that third-party intervention decreases the time until the supported group achieves military victory. Furthermore, third-party interventions, on both the government and opposition sides, increase the time until a negotiated settlement.