Political Regime Type and Warfare: Evidence from 600 Years of European History

Abstract

Is the democratic peace a wholly modern phenomenon or a continuation of previous historical trends? This paper offers the first quantitative analysis of political regime type and conflict in late medieval and early modern Europe. We argue that the modern democratic peace is borne out of centuries of conflict between early parliamentary regimes, which enabled states to raise greater fiscal resources to put toward warfare. To test this argument, we construct a new dyadic panel database of all conflicts, belligerents, and political regime types for the full universe of sovereign polities in Europe between 1200 and 1800. Our database includes more than 900 conflicts and 80 polities. We find that parliamentary regimes fought significantly more than non-parliamentary regimes, both overall and against each other. Furthermore, we find that the causal relationship between parliaments and warfare was reciprocal, with war participation creating the demand for parliamentary institutions, and such institutions creating the capacity for more war. Our results suggest that the institutional predecessors of modern democracies were regimes with significant capacity to make war, but -- until recently -- not enough constraints to prevent it.