This chapter explores the rise of inter-ethnic tensions and violence in large parts of Europe in the wake of the First World War through to Hitler’s appointment as German Chancellor. Although tensions between aspiring nationalist movements and their imperial overlords had been on the rise from the latter third of the nineteenth century onwards, it was the Great War, the implosion of Europe’s land empires and the proliferation of revolutionary movements of the left and right that created the spaces in which violence became possible. Surveying the situation in different European countries – from Russia in the east to Ireland in the west – the chapter analyzes different patterns and logics of violence that emerged long before the Nazis were a serious political force. Without wanting to exaggerate the role of pre−1933 violence as a precursor to the Holocaust, it is clear that the Nazis’ ever-radicalizing policies against the Jews and other minorities did not come out of nowhere. The Great War had raised, but not solved, many of the issues that allowed Nazism to become a dominant force in German politics in the first place.