Providing a comparative and cross-cultural exploration of the role of religion in war from the second millennium BCE until early modernity, this book focuses on the ancient Near East, the Mediterranean basin, and Europe.The significance of religion and its influence on war has come to the forefront in recent years, either through reports from war-torn Syria or Iraq or of terrorist acts in Western capitals. Yet religion has been at the heart of violent conflict throughout human history, and the new-found urgency for informed, academic debate must recognize this. This book explores the historic link between the conduct of war and the growing complexity of a human society conditioned by the ownership of ideological authority which, in most cases, was religious. Chapters, sourced from experts in a range of disciplines, highlight the sheer complexity of the relationship between religion and war, and the variety of experiences it encompasses. Together, they challenge assumptions about the historical background of this pressing and fundamental historical nexus, and caution against simplistic views of its modern instantiations.