The First World War saw tens of millions slaughtered, as the world’s great powers fought a total war for four long years. It was not the rulers who would do the fighting and dying though, that was left to tens of millions of workers and peasants, sent to slaughter each other in trench warfare. In the end the war was only ended through revolutions, made by these lower classes, in Russia and Germany. But why did the war happen at all? Were the Allies merely victims of German aggression? Was it all just a big accident, as the great powers “sleep-walked” into war? Would greater economic integration have prevented the war? These questions remain hotly contested. The fairly established consensus, even among many mainstream historians, that this was an imperialist and unjust war on all sides, is under renewed attack by some historians, military strategists and politicians who want to soften up the population for their current arms race and preparations for war.