The First World War precipitated a crisis in power politics in the creation and maintenance of the post-war international order. Peacemaking after 1918 revealed the difficulties in accommodating traditional practices of power politics within the new normative environment that prevailed in the aftermath of the Great War. This environment emphasised the importance of international law, the principle of self-determination and the creation of international institutions to manage conflicts and promote cooperation. This chapter explores the influence of these norms on territorial claims and settlements in Europe, East Asia and the Middle East, and the different strategies adopted by victors and vanquished. It highlights a fundamental paradox: power politics were marginalised in the creation of a settlement that owed its existence and future viability to a preponderance of power on the part of the victorious allies. The American Senate’s rejection of the Treaty of Versailles, compounded by the onset of the global economic crisis at the end of the 1920s, deprived the international order of the combination of power that had delivered victory in 1918. This would have far-reaching consequences when that order was challenged by revisionist powers that rejected the norms underpinning the Paris peace settlement in Europe.