This article addresses the Anglo-Egyptian dispute over Sudan following the Ottoman defeat in World War One and Cairo’s nominal independence in 1922. Drawing from Foreign Office documents, League of Nations archives, Egyptian parliamentary records and contemporary academic jurisprudence, it traces the failed Egyptian attempt to activate the settlement mechanisms of the Covenant after the assassination of the British governor of Sudan. In parallel, the article investigates the British preparations to face international arbitration, including the hypothetical request for a League mandate over Sudan. Through Cairo’s and London’s perceptions, we can grasp the global reach of the Geneva organization beyond its limited membership and agency. Although the League undertook no measures, the possibility of its intervention triggered competing legal arguments, as well as rival discourses of Egyptian and Sudanese self-determination. Thus, this essay sheds light on a recolonization process pre-dating World War Two. The clash of British and Egyptian imperial projects in the Nile Valley warns historians against forcing a teleology of the end of empire on the interwar roots of decolonization.