The League of Nations was the forerunner to the United Nations. It was an international organization established by the Treaty of Versailles at the end of World War I (1914–18). Since the United States never ratified that treaty, it was not a member.

The league was set up to handle disputes among countries and to avoid another major conflict such as the Great War (which is how World War I was referred to until the outbreak of World War II). But the organization proved to be ineffective; it was unable to intervene in such acts of aggression as Japan’s invasion of Manchuria in 1931, Italy’s conquest of Ethiopia during 1935 to 1936 and occupation of Albania in 1939, and Germany’s takeover of Austria in 1938.

The League of Nations dissolved itself during World War II (1939–45). Though unsuccessful, the organization did establish a basic model for a permanent international organization.