A tribute to the distinguished diplomatic historian, Professor Michael Dockrill (1936-2018), this collection provides a comprehensive overview of the field of twentieth-century British foreign and defence policy. With contributions from the most esteemed academic thinkers in the field, this collection will be of great value to anyone interested in British foreign and strategic policy, whether they are a senior academic or an undergraduate researcher. In memory of the late Professor Dockrill, the essays place British foreign policy in a wide range of geographical, thematic and chronological perspectives. Volume I examines international diplomacy in relation to the conduct of the First World War, the peace-making process that followed it, and the origins of the Second World War, mapping very closely to the interests of Professor Dockrill in the early stages of his career. Focusing on Great Power diplomacy seen through the lens of bi-lateral relations between states, the essaysexplore Britain’s relations not only with European powers, but also with the United States and Japan. The views and operations of the British Foreign Office feature heavily, as do the lives and opinions of diplomats, primarily from the British Diplomatic Service, during the years 1890-1939. Analysing British strategic thinking around war and its consequences, this collection sheds light on the first steps in the evolution of international bodies built to preserve order around the world.