The origins of the First World War remain one of the greatest twentieth century historical controversies. In this debate the role of military planning in particular and of militarism in general, are a key focus of attention. Did the military wrest control from the civilians? Were the leaders of Europe eager for a conflict? What military commitments were made between the various alliance blocks? These questions are examined in detail here in eleven essays by distinguished historians and the editor’s introduction provides a focus and draws out the comparative approach to the history of military policies and war plans of the great powers.