Civil wars are rarely fought between a single insurgent group and the state but rather are crowded arenas in which different rebel organisations must decide whether to fight alone or to cooperate with rivals whose loyalty is never assured. When rebels do ally, how do they govern their relations with one another, and which institutional mechanisms hold a coalition together?

This book answers these questions by introducing the concept of horizontal wartime institutions, the bodies rebel groups build to govern rebel-to-rebel relations when part of coalitions. While the rebel governance literature has focused on how armed groups govern civilians, this book turns to a parallel and overlooked class of institution-building, including joint commands, political councils, and shared governing bodies through which coalition members manage rebel-to-rebel relations. Developing a typology of tactical and strategic, homogeneous and heterogeneous alliances, it shows how the different types of coalitions shape the institutions they create. Furthermore, the book aims to capture the institutional mechanisms that rebels create to govern such institutions, arguing that power-sharing mechanisms create the conditions for cohesive alliances during wartime.

Drawing on the Syrian Civil War and the Italian partisan movement and its National Liberation Committees (1943–1945), the book offers a framework to understand how rebel groups govern rebel-to-rebel relations when part of alliances, and which institutional mechanisms contribute to the alliance’s internal cohesion.

Edoardo Corradi is a Postdoctoral Research Fellow at the University of Bologna. His work focuses on rebel alliances and rebel governance in civil wars and has been published in outlets including Civil Wars, Small Wars & Insurgencies, Media, War & Conflict, Mediterranean Politics, Studies in Conflict & Terrorism, and Italian Political Science Review. He taught courses on Security Studies and International Relations at Sciences Po, Florida International University, and the University of Genoa.