This book explains how and why the Basque separatist armed group ETA decided to end its armed campaign against the Spanish state. The ETA’s armed campaign for Basque independence lasted fifty years and led to more than 800 casualties. This book analyzes the factors that led to ETA ending its campaign of violence in 2011, despite having yet to achieve its political objectives. It explains how the Basque pro-independence movement’s political leadership won an internal battle and brought ETA to a position in which abandoning violence was the only feasible choice. The work argues that the key factor leading to the cessation of violence was the loss of support for armed struggle within the pro-independence social base, and it examines why and how that support decreased so decisively. Written by a former journalist, the narrative is based on more than 30 interviews, including former members of ETA, Spanish judges, former ministers of the Spanish government, political leaders of all Basque political parties—from the Nationalist Left to the Partido Popular (PP)—and international mediators. As such, it is the first book to recount in detail the inside story of the internal struggle within the Nationalist Left movement, and particularly between the political party Batasuna and ETA. This book will be of much interest to students of political violence, ethnic conflict, nationalism, Spanish politics, security studies, and IR.