The League of Nations grew out of the catastrophe of World War I (1914–18). Though the idea of the establishment of a body in which the nations of the world could settle their disagreements had been put forth periodically since antiquity, the League, created at the 1919 Paris Peace Conference, was the first organization of sovereign states designed to be universal and devoted to the settlement of disputes and the prevention of war. The League's failure to prevent the outbreak of World War II in 1939 did not destroy the belief in the need for a universal organization. On the contrary, it bred a determination to learn from the mistakes of the past and to build a new world body more adequately equipped to maintain international peace in the future.
The differences between the League of Nations and the UN begin with the circumstances of their creation. First, whereas the Covenant of the League was formulated after hostilities were ended, the main features of the UN were devised while war was still in progress. The more comprehensive powers assigned to the UN for the preservation of peace may owe something to the urgent conditions in which it was conceived. Second, the Covenant was drawn up in an atmosphere of divided attention at the Paris Peace Conference and was incorporated as part of the peace treaty with Germany. Although countries were permitted to ratify the Covenant and the treaty separately, the link between them was not good psychology and contributed, for example, to the unwillingness of the US Senate to ratify the Covenant. In contrast, the UN Charter was drafted as an independent legal instrument at a conference especially convened for the purpose. Third, the Covenant was hammered out behind closed doors, first by the five major powers of the era—France, Italy, Japan, the UK, and the US—and eventually in conjunction with nine other allied nations. The final text of the UN Charter, on the other hand, was the product of combined efforts of 50 nations represented at the 1945 San Francisco Conference and therefore took into account the views of the smaller nations, especially their concern to give the new organization far-reaching responsibilities in promoting economic and social cooperation and the independence of colonial peoples.