Can heroes legitimize strongly-proscribed and repugnant political behaviors? We exploit the purposefully arbitrary rotation of French regiments to measure the legitimizing effects of heroic credentials. 53% of French line regiments happened to rotate under a specific general, Philippe Petain, during the pivotal WWI battle of Verdun (1916). Using recently declassified intelligence data on 95,314 individuals, we find the home municipalities of regiments serving under Petain at Verdun raised 7% more Nazi collaborators during the Petain-led Vichy regime (1940–44). The effects are similar across joining Fascist parties, German forces, paramilitaries that hunted Jews and the Resistance, and collaborating economically. These municipalities also increasingly vote for right-wing parties between the wars. The voting effects persist after WWII, becoming particularly salient during social crises. We argue these results reflect the complementary role of the heroes of Verdun in legitimizing and diffusing the authoritarian values of their former leader.