In this volume, Mark Douglas presents an environmental history of the Christian just war tradition. Focusing on the transition from its late medieval into its early modern form, he explores the role the tradition has played in conditioning modernity and generating modernity’s blindness to interactions between ‘the natural’ and ‘the political.’ Douglas criticizes problematic myths that have driven conventional narratives about the history of the tradition and suggests a revised approach that better accounts for the evolution of that tradition through time. Along the way, he provides new interpretations of works by Francisco de Vitoria and Hugo Grotius, and, provocatively, the Constitution of the United States of America. Sitting at the intersection of just war thinking, environmental history, and theological ethics, Douglas’s book serves as a timely guide for responses to wars in a warming world as they increasingly revolve around the flashpoints of religion, resources, and refugees.