In the classic formulation of nineteenth-century Prussian general and military theorist Karl von Clausewitz, war is an instrument of national policy by which states pursue their interests using force and violence. This picture presumes that the governmental system wielding such an instrument will be able to control it and, more important, will survive to see the armed conflict brought to a conclusion. For some countries. World War I developed into a test their systems of government could not endure. An essential feature of the conflict—and a measure of its intensity—was the way in which World War I overturned venerable monarchies, and how prominent and long-estabHshed mukinational states dissolved. World War I helped to bring on upheavals in Russia and a number of other major European countries. Political and social tensions existed everywhere in the Europe of 1914, and in the following wartime years all of the great European belligerents experienced events that shook the old order. But neither the war alone nor prewar tensions alone brought on revolution. Irish nationalism, for example, as demonstrated in the uprising of Easter 1916, could not yet dissolve the unity of Great Britain. Nor did the army mutinies in France in 1917 undermine domestic stability. In imperial Russia in 1917 and in Austria-Hungary in 1918, where the strains and traumas of the war combined with existing problems, dramatic breaks with the old order occurred. Russia's debased, unpopular monarchy and inept bureaucracy, its impoverished rural population, and its alienated urban working class had already shown how they could threaten national stability. In addition, talented and determined revolutionary leaders were either on the scene or only a short distance away in foreign exile. Finally, an imperial population in which only half the tsar's subjects were ethnic Russians added an explosive nationalities problem. In Austria-Hungary, the most volatile internal conflict also turned on the question of nationalities, and led finally to the collapse of the old order. Drastic and dramatic change came to the two great powers at different points in the war, and came about in different ways. The two countries' peacetime circumstances varied, and so too did their wartime experiences. In each country, the role of the monarch, the radicalism practiced by leaders of the domestic opposition, and the success of the armed forces and their state of discipline all played a role. There were also important differences concerning the presence or absence of enemy armed forces on the country's soil and the relationship each country had with its wartime allies. Most important in the short run—when the discontented had to decide whether or not to take to the streets—was how well the government functioned in maintaining public order and in guaranteeing an adequate food supply.