In this book, leading scholar Andrew J. Williams examines contemporary liberal thinking on the ending of wars and puts it into its historical context. Using a vast range of archival material, he examines the main strategies used by liberal states to consolidate their gains in the aftermath of war and prevent conflict re-occurring. Considering historical wars from the nineteenth century to the withdrawal from Afghanistan in 2021 and the war in Ukraine since 2022, Williams explores the continuities and changes within western liberalism in response to war and the encouragement of peace. These include, in recent times, the emergence of ‘neoliberalism’, a growing revulsion against ‘humanitarian intervention’ and the evolution of legal attempts to control illiberal regimes. He shows how liberalism and the articulation of international norms and institutions sprang out of historical traditions linked to colonialism but also out of a desire to promote liberty and justice. He examines the attitudes and practices that have distorted liberalism’s essentially emancipatory nature into one that has encouraged hubris in foreign policy and an increasingly divisive set of economic, political and social policies. He suggests that a new liberal impulse to encourage the spread of democracy and international justice is possible, one that returns to a more realistic approach to intervention in international conflicts. The book will appeal to scholars and students of war, conflict and political theory interested in the historical perceptions at the heart of many of the mistakes made by liberalism in the ending of wars. It will also give hope to those who still believe that liberalism can be the organising feature of a just and equitable world order.