Though the just war tradition has an ancient pedigree, like any tradition of thought, it is subject to historical highs and lows. Drawing on examples from the history of warfare from the Crusades to the present day, this book explores the limits and possibilities of the moral regulation of war. It focuses on the tensions which exist between war and morality. The moral ambiguity and mixed record of that tradition is acknowledged and the dangers which an exaggerated view of the justice or moral worth of war poses are underlined. The adoption of a 'dispositional' view of ethical life, in which moral character and moral culture play a decisive part, widens and transforms the ethics of war. Realism resists the application of morality to war. Pacifism harms and benefits the just war tradition in about equal measure. In opposition to the amoral and wholly pragmatic approach of the 'pure' realist, the just war theorist insists on the moral determination of war where that is possible, and on the moral renunciation of war where it is not. Moral realism is what the just war tradition purports to be about. Legitimate authority has become entirely subordinated to the concept of state sovereignty. If moderate forms of consequentialism threaten the principle of noncombatant immunity, more extreme or purer forms clearly undermine it. The strategic and the ethical problems of counterterrorism are compounded by the emergence of a new and more extreme form of terrorism.