Over the past two decades or so, medieval geopolitics have come to occupy an increasingly prominent place in the collective imagination-and writings-of International Relations scholars. Although these accounts differ significantly in terms of their respective analytical assumptions, theoretical concerns and scholarly contributions, they share at least one common - arguably, defining - element: a belief that a careful study of medieval geopolitics can help resolve a number of important debates surrounding the nature and dynamics of "international" relations. There are however three generic weaknesses characterizing the extant literature: a general failure to examine the existing historiography of medieval geopolitics, an inadequate account of the material and ideational forces that create patterns of violent conflict in medieval Latin Christendom, and a failure to take seriously the role of "religion" in the geopolitical relations of medieval Latin Christendom. This book seeks to address these shortcomings by providing a theoretically guided and historically sensitive account of the geopolitical relations of medieval Latin Christendom. It does this by developing a theoretically informed picture of medieval geopolitics, theorizing the medieval-to-modern transition in a new and fruitful way, and suggesting ways in which a systematic analysis of medieval geopolitical relations can actually help to illuminate a range of contemporary geopolitical phenomena. Finally, it develops an historically sensitive conceptual framework for understanding geopolitical conflict and war more generally.