This book focuses on the way in which ideas and discourses of security have shaped the conduct of international relations in the past. Its main concerns include how historical actors conceived of security as an idea, used it in their writings and discussions, pondered its implementation and turned conceptions into practice. Security efforts shaped international relations at a crucial moment in history, during the first half of the nineteenth century, when international systems and global divisions of power dramatically changed. International involvement with Mediterranean piracy reflected all of these changes. Yet, in order to better grasp the impact of security considerations, one must look at the means by which contemporaries made sense of, were swayed by and, also, turned against the concept. Security must be historicised.