Sharing Battlespace: Aims, Ability, and Interests

• In Event: Resources, Logistics, and War

Abstract

States frequently go to war with partners; 32 of the 62 (52%) interstate wars fought between 1900 and 2003 involved multinational forces on at least one side. However, they do not always fight side-by-side on the battlefield; in the 371 major battles waged during those 32 interstate wars, only 178 (48%) involved multinational forces sharing the same combat space. Why and when do militaries fielded by multiple belligerents fight together in battle? Battlefield coalitions are amalgamations of officers, troops, and materiel provided by multiple discrete actors with variable war aims that, in theory, possess greater resources, capabilities, and likelihood of collective achievement of combat objectives than forces fighting along (Riker 1962). However, like all collective entities, they are subject to coordination problems including principal-agent problems, free-riding and other transaction costs (Leighton, 1952: 401–402, 422; Moller, 2016; Weitsman, 2003a: 104; Wilkins, 2006: 1122–1123). Fighting as part of a battlefield coalition may provide some benefits but is not a cost-free, obvious choice, even for belligerents fighting on the same side in a war. We argue that three variables explain why and when belligerents fighting on the same side in a war choose to take the additional, organizationally costly step of fighting together in the same battlespace: belligerents’ war aims, logistical capacities, and stakes in the coming battle. When belligerents share overarching war aims and it is logistically easy to for each member to both project forces into and sustain combat effort into a potential battlespace, they will be likely to fight alongside one another. When their overarching war aims diverge and it is logistically difficult for belligerents to project force into and sustain combat effort in a potential battlespace, they will be unlikely to fight alongside one another. When belligerents’ overarching war aims are shared and their logistical capacity is limited or when their overarching war aims diverge but their logistical capacity is significant, the likelihood that the forces will fight alongside one another in combat depends on the stakes of the battle. When the stakes involved are high, the belligerents will be more likely to work to fight together despite divergent war aims or limited logistical capacity. When the stakes involved are low, however, the belligerents will be unlikely to make a significant effort to overcome the inertia and hurdles of divergent war aims or limited logistical capacity. We assess our hypotheses through examinations of German and Austro-Hungarian coalition fighting on the Eastern Front during World War I and British, American, and Chinese coalition fighting in Burma during World War II. These cases, by offering significant variation on all three of our variables over time, provide a particularly informative initial tests of our claim and support our hypotheses.

Authors

• Rosella Cappella Zielinski, Boston University

• Ryan D. Grauer, University of Pittsburgh