This book improves our understanding of battlefield coalitions, providing novel theoretical and empirical insight into their nature and capabilities, as well as the military and political consequences of their combat operations. The volume provides the first dataset of battlefield coalitions, uses primary sources to understand how non-state actors of varying types form such groupings, reports interviews with policymakers illuminating North Atlantic Treaty Organization operations, and uses cases studies of various wars waged throughout the nineteenth, twentieth, and twenty-first centuries to understand how other such collectives have operated. Part I introduces battlefield coalitions as an object of study, demonstrating how they are distinct from other wartime collectives. Using a novel dataset of actors fighting in 492 battles during interstate wars waged between 1900 and 2003, it provides, for the first time, a comprehensive portrait of the universe of battlefield coalitions. Part II
