Hello, I'm an expert in international relations and history. I specialize in the study of global organizations and their impact on world affairs. Today, I'll be discussing a pivotal organization from the early 20th century: the League of Nations.
The League of Nations was an international organization founded after World War I as part of the Treaty of Versailles. Its purpose was to maintain world peace and prevent future conflicts through collective security and disarmament. The League was established on January 10, 1920, and it had 42 founding members. However, not every country that was invited to join did so, and some significant nations never became members.
One of the most notable absences from the League was the United States. Despite President Woodrow Wilson's significant role in the creation of the League and his advocacy for its formation, the United States never joined. Wilson faced strong opposition from the U.S. Senate, which was largely isolationist and reluctant to commit the country to international entanglements. The Senate refused to ratify the Treaty of Versailles, which included the covenant establishing the League of Nations, and as a result, the United States remained outside the organization.
Another significant country that did not join the League was the Soviet Union. The Soviet Union was not invited to join the League initially due to ideological differences and the fact that it was under a period of isolation following the Russian Revolution. However, the League did eventually extend an invitation to the Soviet Union to join, which it accepted in 1934. Yet, the Soviet Union's membership was short-lived. In 1939, following the Soviet invasion of Finland, the League expelled the Soviet Union, making it the only member to be formally expelled from the organization.
It's also worth noting that there were other countries that chose not to join the League for various reasons. Some were due to political considerations, while others were influenced by economic or strategic factors. The League's inability to prevent aggression by the Axis powers in the 1930s, particularly the invasion of Manchuria by Japan and the annexation of Austria and Czechoslovakia by Germany, ultimately led to its downfall and the establishment of its successor, the United Nations, in 1945.
In conclusion, while the League of Nations was an ambitious attempt to foster global cooperation and prevent war, its membership was not universal. The absence of key powers like the United States and the expulsion of the Soviet Union significantly impacted the League's effectiveness and contributed to its eventual dissolution.
read more >>

The Soviet Union was the only country to be expelled by the League (in 1939, following its invasion of Finland). Despite formulating the concept and signing the Covenant, the United States never joined the League of Nations.read more >>