Rationalist Explanations for Two-Front War

Abstract

By extending the extant costly-lottery models of dyadic war to three-party bargaining scenarios, we offer rationalist explanations for two-front war, where a state at the center is fought by two enemies at opposing peripheries. We found that even though private information exists only in one front, war can break out in both fronts. Because the war outcome in one front can affect the outcome in the other through the shift of military balance, a peripheral state may preventively join the war ongoing in the other front to leverage its power (e.g. Napoleonic Wars), or the central state may preemptively initiate war in one front to establish its preponderance in the other (e.g. World War I). These findings echo Waltz’s neorealism concern that a multi-polar system may not be so stable as the bipolar system that bargaining models of dyadic war commonly presume.