This book presents, tests, and analyzes what has come to be known as the territorial explanation of war, arguing that a key both to peace and to war lies in understanding the role territory plays as a source of conflict and inter-group violence. Of all the issues that spark conflict, territorial disputes have the highest probability of escalating to war. Settling territorial disputes and establishing mutually recognized boundaries can produce long periods of peace between neighbours, even if other salient issues arise. While territory is not the only cause of war and wars arise from other issues, territory is one of the main causes of war, and learning how to manage it, can, in principle, eliminate an entire class of wars. Containing five previously published essays and six new essays on the territorial explanation of war over twenty years by John Vasquez (one of the world's leading IR scholars and theorists) and Marie Henehan, it builds on the argument presented in "The War Puzzle" (Vasquez, 1993). "Territory, War, and Peace" will be of great interest to all students of war and conflict studies, causes of war and peace, international security and strategic studies.