This study focuses on the efforts of Sir Charles Addis, a London merchant banker, to preserve and then restore the pre-1914 system of cosmopolitan capitalism. Our central research question is to understand why this business leader fought to preserve cosmopolitan capitalism when so many of his peers acquiesced to and even championed its demise. Addis's moral ideal was an international economic order in which the nationality of firms had a limited impact on the strategies of managers. The First World War profoundly changed the international business environment and dramatically increased the salience of firm nationality in international business. Addis, who was a committed classical liberal, fought against this trend to a degree that is hard to explain with reference to economic selfinterest alone. The paper, which is based on a range of sources including Addis's diary, explores Addis's connections to, and views of, 'German' bankers, his relations with the British government, and the political economy of the reparations imposed on Germany by the Versailles Peace settlement.