Academic Seminar with Saumitra Jha

Saumitra Jha

Political Trenches: War, Polarization and Partisanship

with Pauline Grosjean, Michael Vlassopoulos and Yves Zenou

We study the dynamics between local segregation, partisan conversion, and political polarization. We use the large-scale exogenous assignment to peers in a high-stakes historical context: that of universally conscripted soldiers assigned from each of 35,000 municipalities to line infantry regiments in WWI France. We wed these to municipality-level voting data immediately before and after the war. We first find that municipalities whose soldiers were assigned to the same line regiment in WWI converge politically after the war. Further, by exploiting local discontinuities in regimental assignment across 435 military boundaries, we demonstrate that adjacent municipalities that happened to be assigned to different regiments containing strong political partisans diverge from each other, towards the political preferences of those partisans. These further generate sharp local differences across military boundaries after the war, manifesting themselves both in extreme local political polarization in the inter-war period and ultimately in violent civil conflict between Collaborators and the Resistance during WWII.