They envisioned a brave new world, and what they got was fascism. As vibrant as its counterparts in Paris, Munich, and Milan, the avant-garde of Florence rose on a wave of artistic, political, and social idealism that swept the world with the arrival of the twentieth century. How the movement flourished in its first heady years, only to flounder in the bloody wake of World War I, is a fascinating story, told here for the first time. It is the history of a whole generation's extraordinary promise--and equally extraordinary failure.

The "decadentism" of D'Annunzio, the philosophical...