Long considered the embodiment of national resilience and fraternal loyalty in the wake of World War I, Fernand Léger’s art overshadows a far less heroic story, one that prompts a demythification of his legendary identification with the working class and provokes important questions about psychic trauma. This book draws on Léger’s wartime letters to reassess his work and present an entirely new perspective on how the artist’s war experience informed his art. Maureen G. Shanahan traces the legacy of war and historical trauma in Léger’s work and uses the crisis of masculinity generated by World War I to explain the contradictions and paradoxes of his art and writing during and after the war. Drawing upon psychoanalytic and gender theory as well as memory studies, Shanahan historicizes the work of Léger and the Purist art movement within the psychiatric discourse of the era and anxieties about neurasthenia, which was associated with German Expressionism, Dada, and New Objectivity artists. Notably, Shanahan dismantles Léger’s machine aesthetic as a utopian and regenerative investment and explores the significance of Léger’s collectives of soldiers, female nudes, mass-produced objects, divers, and cyclists—his “machine men”—as vehicles for displacing trauma and disavowing loss. Informed by extensive archival research, this volume turns Léger into a case study of Cubism’s most radical moment, machine modernism’s relationship to war trauma, and aesthetic positions between Socialist Realism and geometric abstraction.