Much of the empirical literature suggests that outside interventions tend to lengthen the expected duration of civil wars; conversely, the policy community often acts as if they hold the opposite expectation for the outcome of intervention. We argue that the divergence can be found in how models of intervention are specified in the literature. We propose a model with two novel contributions. First, we incorporate mediations as the key to resolving the strategic problems that the civil war parties face. Second, we account for the decaying effect of interventions over time. Our results suggest that diplomacy is critically important for understanding the duration of civil conflicts. We find that mediation has a dramatic effect on the expected duration of a civil war, and that when controlling for diplomatic efforts, economic interventions can also reduce the expected duration.