At its greatest extent from 28 September 1934 to 23 February 1935, it had 58 members. After some notable successes and some early failures in the 1920s, the League ultimately proved incapable of preventing aggression by the Axis powers in the 1930s. The credibility of the organization was weakened by the fact that the United States never joined the League and the Soviet Union joined late and was soon expelled after invading Finland. Germany withdrew from the League, as did Japan, Italy, Spain and others. The onset of the Second World War showed that the League had failed its primary purpose, which was to prevent any future world war. The League lasted for 26 years; the United Nations (UN) replaced it after the end of the Second World War and inherited several agencies and organisations founded by the League.