Drawing on more than 150 interviews with former IRA, INLA, UVF and UFF prisoners, this book is a major analysis of why Northern Ireland has seen a transition from war to peace. Most accounts of the peace process are ‘top-down’, relying upon the views of political elites. This book is ‘bottom-up’, analysing the voices of those who actually ‘fought the war’. What made them fight, why did they stop and what are the lessons for other conflict zones? Using unrivalled access to members of the armed groups, the book offers a critical appraisal of one-dimensional accounts of the onset of peace, grounded in ‘mutually hurting stalemate’ and ‘ripeness’, which downgrade the political and economic aspects of conflict. Military stalemate had been evident since the early 1970s and offers little in explaining the timing of the peace process. Moreover, republicans and loyalists based their ceasefires upon very different perceptions of transformation or victory. Based on a Leverhulme Trust project, the book offers an analysis based on subtle interplays of military, political, economic and personal changes and experiences. Combined, these allowed combatants to move from violence to peace whilst retaining core ideological beliefs and maintaining long-term constitutional visions. Former prisoners now act as ambassadors for peace in Northern Ireland. Knowledge of why and how combatants switched to peaceful methodologies amid widespread skepticism over prospects for peace is essential to our understanding of the management of global peace processes.