Expansion of rebellion: From periphery to heartland

Why do some rebellions expand gradually as rebel groups challenge in sequence, whereas other rebellions explode instantaneously as rebel groups challenge in unison? To address this question, we develop a dynamic and spatial model of rebellion that illustrates patterns of war fought between a hegemon (government) and its challengers (rebel groups). Our model incorporates three features into the standard coordination game: (a) potential rebel groups (players) are uncertain about the government's strength; (b) battle outcomes are unpredictable; (c) these groups can be heterogeneous in terms of resolve and strength. In contrast to what existing theories commonly presume, our theory suggests that the sequence and timing of challenges are determined endogenously, depending on rebel groups' resolve and strength. Through equilibrium analyses, we demonstrate that while simultaneous challenges are likely when rebel groups are relatively homogeneous, sequential challenges may emerge when one group is outstanding in terms of resolve and strength. Once this group rebels, other groups are inclined to 'bandwagon' as battles evolve, because the government is gradually revealed to be weak and because accumulated challenges shift the balance of power away from the government. Our theory also addresses why rebellious movements often spread across the periphery and can eventually reach the heartland as if a siege tightens. With an eye to historical incidents, we delineate four patterns of rebellion: (i) snowballing rebellion, which gradually escalates as more challengers are drawn in (Napoleonic Wars); (ii) catalytic rebellion, in which an instigator provokes a galvanizing event to inspire others to challenge the government (Boshin War); (iii) partially coordinated rebellion, which is initiated by a subset of ex post rebel groups (American Civil War, Yugoslav Wars); (iv) fully coordinated rebellion, in which all the rebel groups challenge collectively (American Revolution, Glorious Revolution).