This book offers a new perspective on peace missions in intra-state wars, based on comparative field research. In theoretical terms, this book proposes a new definition of peace operation success based on two crucial elements: the (re)establishment of order and the accomplishment of the mandate. The work presents a new typology for assessing peace operations as failures, partial failures, partial successes, or successes. This focus on ‘blurry’ outcomes provides a clearer theoretical framework to understand what constitutes successful peace operations. It explains the different outcomes of peace operations (based on the type of success/failure) by outlining the effect(s) of the combination of the key ingredients-strategy and the type of interveners. Empirically, this book tests the saliency of the theoretical framework by examining the peace operations which took place in Somalia, Sierra Leone and Liberia. This book refutes the classification of these three cases as the ‘worst’ context for ‘transitional politics’, and demonstrates that peace operations may succeed, partially of totally, in challenging contexts, and that the diverse outcomes are better explained by the type of intervener and the strategy employed than by the type of context. This work shows that, for a peace operation in an intra-state war, the adoption of a deterrence strategy works best for re-establishing order while the involvement of a great power facilitates the accomplishment of the mandate. This book will be of much interest to students of peacekeeping, conflict resolution, civil wars, security studies and IR in general.