After World War I, US President Woodrow Wilson helped to build an international peacekeeping organization.  


  • The League of Nations was established at the end of World War I as an international peacekeeping organization.
  • Although US President Woodrow Wilson was an enthusiastic proponent of the League, the United States did not officially join the League of Nations due to opposition from isolationists in Congress.
  • The League of Nations effectively resolved some international conflicts but failed to prevent the outbreak of the Second World War.

The experience of the First World War

World War I was the most destructive conflict in human history, fought in brutal trench warfare conditions and claiming millions of casualties on all sides. The industrial and technological sophistication of weapons created a deadly efficiency of mass slaughter. The nature of the war was thus one of attrition, with each side attempting to wear the other down through a prolonged series of small-scale attacks that frequently resulted in stalemate.
Though the origins of the war were incredibly complex, and scholars still debate which factors were most influential in provoking the conflict, the structure of the European alliance system played a significant role.1^1 This system had effectively divided Europe into two camps, based on treaties that obligated countries to go to war on behalf of their allies.
In the immediate aftermath of the war, American and European leaders gathered in Paris to debate and implement far-reaching changes to the pattern of international relations.2^2 The League of Nations was seen as the epitome of a new world order based on mutual cooperation and the peaceful resolution of international conflicts.

The establishment of the League of Nations

The Treaty of Versailles was negotiated at the Paris Peace Conference of 1919, and included a covenant establishing the League of Nations, which convened its first council meeting on January 16, 1920.
The League was composed of a General Assembly, which included delegations from all member states, a permanent secretariat that oversaw administrative functions, and an Executive Council, the membership of which was restricted to the great powers.3^3 The Council consisted of four permanent members (Great Britain, France, Japan, and Italy) and four non-permanent members. At its largest, the League of Nations was comprised of 58 member-states. The Soviet Union joined in 1934 but was expelled in 1939 for invading Finland.
Members of the League of Nations were required to respect the territorial integrity and sovereignty of all other nation-states and to disavow the use or threat of military force as a means of resolving international conflicts. The League sought to peacefully resolve territorial disputes between members and was in some cases highly effective. For instance, in 1926 the League negotiated a peaceful outcome to the conflict between Iraq and Turkey over the province of Mosul, and in the early 1930s successfully mediated a resolution to the border dispute between Colombia and Peru.
However, the League ultimately failed to prevent the outbreak of the Second World War, and has therefore been viewed by historians as a largely weak, ineffective, and essentially powerless organization.4^4 Not only did the League lack effective enforcement mechanisms, but many countries refused to join and were therefore not bound to respect the rules and obligations of membership.

The United States and the League of Nations

US President Woodrow Wilson enunciated the Fourteen Points in January 1918. The Fourteen Points laid out a comprehensive vision for the transformation of world politics. Wilson believed that affairs between nations should be conducted in the open, on the basis of sovereignty, self-determination (the idea that all nations have the right to choose their own political identity without external interference), and the disavowal of military force to settle disputes. Wilson’s vision for the postwar world was hugely influential in the founding of the League of Nations.5^5
President Wilson’s intense lobbying efforts on behalf of US membership in the League of Nations met with firm opposition from isolationist members of Congress, particularly Republican Senators William Borah and Henry Cabot Lodge. They objected most vociferously to Article X of the League’s Covenant, which required all members of the League to assist any member threatened by external aggression. In effect, Article X would commit the United States to defending any member of the League in the event of an attack. Isolationists in Congress were opposed to any further US involvement in international conflicts and viewed Article X as a direct violation of US sovereignty. As a result, the Senate refused to ratify the treaty, and the United States never became a member of the League of Nations.6^6
Though the League had failed to prevent the outbreak of another world war, it continued to operate until 1946, when it was formally liquidated. By this time, the Allied powers had already begun to discuss the creation of a new successor organization, the United Nations. The United Nations, which is still in existence today, was based on many of the same principles as the League of Nations, but was designed specifically to avoid the League’s major weaknesses. The UN boasts much stronger enforcement mechanisms, including its own peacekeeping forces, and the membership of the UN is substantially larger than that of the League even at its peak.

What do you think?

Why did the United States refuse to join the League of Nations?
How effective was the League of Nations as an international peacekeeping organization?
Do you think the League of Nations could have prevented the outbreak of the Second World War if the United States had joined?