Wilson advocated international law and arbitration. In January 1917 he had made an unsuccessful attempt to persuade the belligerents to end the war, calling for a "peace without victory". After the USA had entered the war, Wilson outlined his view on a post-war settlement through his "Fourteen points". These became the guiding principles for the Paris Peace Conference (1919-20), and included the establishment of the League of Nations. However, Wilson failed to obtain ratification of the Treaty of Versailles, and the USA did not join the League of Nations.
Lange served as secretary to the Norwegian Nobel Committee from 1901 to 1909, and he played an important role in the founding and development of the Norwegian Nobel Institute that opened in 1905. He advocated peace and disarmament and he attended several international peace conferences. Lange was secretary general of the Inter-Parliamentary Union from 1909 to 1933. During WWI he moved the office of the Inter-Parliamentary Union to Oslo, in order to continue and preserve the work of the Union and to protect its records from possible wartime destruction.