Coalition Quality and Multinational Dispute Outcomes1

Multinational military coalitions are an increasingly common phenomena in international conflict, presumably because coalitions are more likely to secure their conflict aims than single states. Yet what makes a coalition more or less likely to succeed is poorly understood. We argue that the quality of multinational military coalitions—in terms of the coalition’s skill, coordination, and legitimacy—can provide better strategic decisions, more harmonious relations within the coalition, and thus a greater chance of securing conflict aims. Empirical testing reveals that elements of coalition quality do in fact affect the probability of military success: a history of success, both alone and with the same coalition partners, predicts military success. Moreover, increasing a coalition’s legitimacy via more diverse members has a weak effect, indicating that diversity comes at the expense of coordination and cooperation challenges. Last, we find that elements of coalition quality affect initiating and defending coalitions differently.