The 1949 Geneva Conventions are the most important rules for armed conflict ever formulated. To this day they continue to shape contemporary debates about regulating warfare, but their history is often misunderstood. For most observers, the drafters behind these treaties were primarily motivated by liberal humanitarian principles and the shock of the atrocities of the Second World War. This book tells a different story, showing how the final text of the Conventions, far from being an unabashedly liberal blueprint, was the outcome of a series of political struggles among the drafters. It also concerned a great deal more than simply recognizing the shortcomings of international law revealed by the experience of war. To understand the politics and ideas of the Conventions' drafters is to see them less as passive characters responding to past events than as active protagonists trying to shape the future of warfare. In many different ways, they tried to define the contours of future battlefields by deciding who deserved protection and what counted as a legitimate target. Outlawing illegal conduct in wartime did as much to outline the concept of humanized war as to establish the legality of waging war itself. Through extensive archival research and critical legal methodologies, Preparing for War establishes that although they did not seek war, the Conventions' drafters prepared for it by means of weaving a new legal safety net in the event that their worst fear should materialize, a spectre still haunting us today.