The last thirty years of the nineteenth century were for the peoples of western Europe, if not for those of the world as a whole, an era of virtually unbroken peace. In western Europe there was an interval between the Wars of Unification which had shattered the pattern of the Vienna Settlement and the conflicts over the lands of the disintegrating Turkish empire which were to develop into the first World War. Even outside this area there were only three instances where two major powers were involved in mutual conflict—the Russo-Turkish War of 1877–8, the Sino-Japanese War of 1894 and the Spanish-American War of 1898—and these quarrels, either by their nature or from the agreed policy of the great powers, were kept strictly within local bounds. European powers protecting or extending their interests in Africa and Asia were constantly engaged in minor conflicts, and Great Britain in 1899 became involved in a struggle with the Boer Republics of South Africa which assumed proportions transcending the category of ‘small wars’; but within Europe itself, outside the Balkan Peninsula, the Peace of Frankfurt signed between France and the victorious German empire in 1871 ushered in forty-three years of uninterrupted peace.

Yet during these years the great powers, particularly those of Europe, were preparing for war with a diligence for which modern history had hitherto offered no parallel. Engines of war, maritime and military, were multiplied prodigiously in number, complexity, and cost. Defence preparations received an ever-swelling allocation in national budgets; and the male populations of the mainland states of Europe became bound to military service from the end of their adolescence until the onset of later middle age.