This narrative history explores the emergence of one of the most influential Nationalist movements of modern Europe. It explains how and why the movement united the far right with the far left in a militant campaign to wrest control of France from the moderate republicans who were attempting to stabilize the country after a century of political volatility. The agitation groups, propaganda machines, street-fighting gangs, and political hustlers, who made up the Nationalists, all campaigned for one end: to overthrow the Third Republic. The eruption of the Dreyfus Affair (1894-1899) provided the Nationalists with a convenient target for their assaults: the Dreyfusard defenders of a wrongly convicted Jewish army captain, Alfred Dreyfus. This work, based on original archival research in France, argues that the Nationalists posed a real and dangerous threat that dissipated only when their goals were adopted by more moderate competing groups.