When, if ever, is a political community justified in going to war? Is there such a thing as a just war? If there is, how should it be waged? Does anything go, or must communities respect strict limitations when conducting hostilities? These are hard questions to answer. The principal conceptual framework for addressing them is the just war tradition. While its key tenets-e.g., the principles of ‘just cause’, ‘last resort’, and ‘discrimination’-are frequently invoked by today’s political and military leaders, the just war tradition boasts a long and venerable history, encompassing contributions from classical political thought, early Christian political theology, medieval chivalric thinking, early modern jurisprudence, and contemporary political philosophy. Thus defined, the tradition comprises an evolving body of thought that aims to distil the wisdom of the ages into a useful guide for thinking through the ethical questions war raises. This project makes a novel contribution to this tradition by focusing upon the concept of victory, and asking what it means in relation to the idea of just war. Although the idiom of ‘winning’ is central to how war is framed, just war scholars have been reticent to engage it. Why is this, and is it a mistake? Is victory a helpful concept for thinking through the ethical issues that war raises, or have just war scholars been wise to excise it from their discourse? Straddling International Political Theory, War Studies, and the History of Political Thought, this project thereby presents a new approach to the old and overlooked, yet also urgent, question of what victory means in relation to just war. In so doing, it employs the just war tradition to shed new light on what victory might mean, while using victory as a prism through which to develop a critical ‘historical ontology’ of just war.