Drawing on an array of archival material, this study sheds light on Sir George Russell Clerk, an important, yet forgotten figure in British and European diplomatic history. During the First World War, Clerk was a senior Foreign Office official strongly sympathetic to the cause of the 'oppressed nationalities' of the Austro-Hungarian Empire. This biographical study focuses on the most significant part of Clerk’s career, his role as a nation-builder in post-war Europe until his eventual downfall at the hands of Antony Eden, and retirement in 1937. This is an excellent account of the thoughts and deeds of a remarkable man in British History.