A second edition of this leading introduction to the origins of the First World War and the pre-war international system. William Mulligan shows how the war was a far from inevitable outcome of international politics in the early twentieth century and suggests instead that there were powerful forces operating in favour of the maintenance of peace. He discusses key issues ranging from the military, public opinion, economics, diplomacy and geopolitics to relations between the great powers, the role of smaller states and the disintegrating empires. In this new edition, the author assesses the extensive new literature on the war's origins and the July Crisis as well as introducing new themes such as the relationship between economic interdependence and military planning. With well-structured chapters and an extensive bibliography, this is an essential classroom text which significantly revises our understanding of diplomacy, political culture, and economic history from 1870 to 1914.