This book assesses the use of ‘mercenaries’ by states, and their integration into the national armed forces as part of a new hybridisation trend of contemporary armies. Governments, especially in the West, are undertaking an unprecedented wave of demilitarisation and military budget cuts. Simultaneously, these same governments are increasingly opening their armies up to foreign nationals and outsourcing military operations to private companies. This book explores the impact of this hybridisation on the values, cohesion and effectiveness of the armed forces by comparing and contrasting the experiences of the French Foreign Legion, private military companies in Angola, and the merging of private contractors and American troops in Iraq. Examining the employment of foreign citizens and private security companies as military forces and tools of foreign policy, and their subsequent impact on the national armed forces, the book investigates whether the difficulties of coordinating soldiers of various nationalities and allegiances within public-private joint military operations undermines the legitimacy of the state. Furthermore, the author questions whether this trend for outsourcing security can realistically provide a long term and positive contribution to national security. This book will be of much interest to students of private military companies, strategic studies, international security and IR in general.