Statehood, territory and international spaces are at the heart of a specific branch of international law: the international law of territory. International territorial disputes and their settlement are investigated from the standpoint of legal titles: acquisition and loss of territorial sovereignty, use of force (annexation, conquest), the right of peoples to self-determination (and secession), ius cogens norms etc. The existence, among others, of de facto states, puppet states, ‘drowning’ and ‘failed’ States shows the Protean character of statehood. Peculiar territorial regimes are likewise examined: international administration, leases, servitudes, protectorates, international cities and territories, as well as the League of Nations Mandates and the United Nations Trusteeship system.