This book offers a genuinely comparative analysis of the dictatorships that launched the Second World War: their origins, nature, dynamics, and common ruin. It seeks to understand their similarities and differences historically, without recourse to failed generic concepts such as "fascism." The result is an unconventional and compelling analytical overview from territorial unification in the 1860s to national catastrophe in 1943/45 that places Fascism and Nazism firmly in the tradition of revolutionary mass politics inaugurated in the French Revolution.