Quiz Questions on the Versailles Treaty (1919) The First World War was fought by the Allies to be the war to end all wars. What liberal principles would guide the new peace? What went wrong with the principle of national self-determination? What went wrong with the principle of open diplomacy? What went wrong with the idea of 'colonial mandates'? Why was it a mistake to punish Germany so severely? What made the League of Nations an ineffective international organization?