Political Institutions, Resources, and War: a General Theory and 900 Years of Empirics from Ancient Rome

Abstract: How do political institutions shape the incentives to go to war? I contribute by providing a theoretical model and empirically investigating the monumental political transition of recorded history - the Roman transition from Republic to Empire. My hypothesis is that political institutions determine the type of conflict but not the level. By increasing the breadth of the ruling political coalition, more people share private goods but more people benefit from public goods. These forces are opposed and predict an ambiguous amount of total military activity. To test this idea, I compile a uniquely large and disaggregated spatio-temporal data set on ancient Roman battles and human settlement around the Mediterranean. The raw data and the regression analysis show that dictators engage in battles that are less desirable for citizens of the state.