On November 11, 1918, World War I came to an end. Although the guns fell silent on the western front, military violence continued. Border wars, civil wars, and armed uprisings became endemic. In addition to such traditional forms of military violence, a new phenomenon emerged and became a hallmark of the interwar years: street violence produced by clashes between the “political soldiers” of opposing social and political “fronts.” If in international terms the interwar years represented an era of cold war between defenders and opponents of the order created at the Paris Peace Conference, in domestic terms it was an era of civil war, open and latent, between the (primarily Marxist) left and the (primarily bourgeois) right. Interwar domestic politics opened not with the end of the First World War in 1918 but with the Russian Revolution of 1917 and closed not with the beginning of the Second World War but with its end. If before 1914 war was the continuation of politics by other means, after 1917 politics became a continuation of war by other means, politics in a new, martial key.

There were a number of reasons for the postwar militarization of politics. War surplus made the hardware readily available. Arms were ubiquitous, and some states lost their monopoly on the means of violence. In addition to military hardware, there was a form of social war surplus that facilitated the militarization of politics: veterans. Many middle- and upper-class officers were unable to find their way in the postwar world, unable to recapture the status and sense of adventure they had enjoyed during the war; for many ordinary soldiers the war was the decisive formative experience of their lives, and they were unable to free themselves from its spell. As a result, every belligerent nation was host to a substantial postwar army of men unable to psychologically demobilize. In dealing with this problem the established democracies had an advantage. While the postwar military forces in Germany and Austria were limited by treaty and in Italy by fiscal considerations, France and Britain could absorb those who wanted to continue their military careers in relatively expanded peacetime armies, ship them off to colonies, or, in the case of Britain, to Ireland. In Germany, Austria, and Italy there were no safety valves for militarized veterans, and they were driven like a poison into the body politic.