He is a historian of modern France and its empire, with a broad training in cultural and intellectual history. Their research has led from original interests in labor history, political economy and Marxist thought to the history of medicine, war, and colonialism. His first book, What Nostalgia Was: War, Empire, and the Time of a Deadly Emotion (Chicago, 2017) explores how people once died of nostalgia in order to tell a larger story about social transformation in the eighteenth and nineteenth centuries.