Window of Opportunity: War and the Origins of Parliament

Two important puzzles characterize the development of pre-modern Eurasian polities. First, most rulers convened councils of nobles, but only European monarchs expanded them to create parliaments. Second, war was common throughout Eurasia, but only in Europe did it correlate with the formation of parliaments. We advance a new argument about the emergence of parliaments that accounts for both stylized facts while integrating the literature highlighting the rulers' need to finance wars with that emphasizing the importance of the medieval communal revolution. Using novel data, we document a ‘no communes, no parliaments’ rule: monarchs established parliaments only after they had fostered the creation of self-governing towns (aka communes). We also show that war was a significant predictor of parliamentary births across medieval Europe – but only during a window of opportunity that opened after a polity had experienced the communal revolution.