During the great transformation of the period 1914–1921, some of the elements of fascist warfare were distilled. The trend towards total mobilization entailed the military mobilization not only of men, but also of the entire ‘national community’. Modern ideologies such as ethno-nationalism intersected with modern technology, producing an enormous increase in destructive force. Fascism was unthinkable without a war culture, including a totalizing militarism, an obsessive cult of death, and a hierarchical racial perception of the enemy. It derived not only from the Great War, but also from long-term traditions and colonial warfare. Elements of fascist warfare showed convergence with changes in the military under the impact of modern war. The chapter explores also (transnational) learning processes, limits to fascist warfare, and the genocidal potential.