We ask how enforcement can endogenously emerge in a landscape in which only raw power, iron fists, govern the interaction of agents. If two agents are ranked in terms of power, the more powerful one can expropriate, at a cost, the less powerful one. Alternatively, both agents can engage in surplus-augmenting cooperation (e.g. trade). If expropriation is not too costly and cooperation is not overwhelmingly productive, for any pair of ranked agents the possibility of expropriation prevents cooperation. The more powerful agent finds it profitable to expropriate the less powerful one.