In the 2011 wave of popular uprisings shaking authoritarian rule in the Middle East, mass societal mobilizations have been the crucial factor. But institutional actors, especially armies, are also playing an active role. Armies in the region have generally had less and less involvement in formal interstate wars and consequently have played more of a role, willingly or not, in underpinning regimes. Recent events demonstrate two patterns: armies that have refused to play this role (Egypt, Tunisia) and armies that have been willing, at least for some time, to answer the regimes’ requests to engage in repression (Bahrain, Yemen, Syria) or even civil war (Libya). How can we account for the military's growing role in civil strife or civil peace?