Answer:
The reasons for the failure of the League of Nations of 1920 include:
3. The League of Nations was created by the unpopular Treaty of Versailles
5. The US Senate did not allow the US to become involved in the League of Nations.
Explanation
The League of Nations otherwise known as the Society of Nations was a global intergovernmental diplomatic organization aimed as maintaining and promoting world peace. It was established in 1920 by the Treaty of Versailles with its headquarter in Geneva, Switzerland. It was established after the first world war to encourage disarmament and prevent war and armed conflicts. However, the League of Nations failed to achieve most of its goals with the outbreak of the second world war. Some of the reasons for the failure of the League of Nations include: the Treaty of Versailles that established the League of Nations was an unpopular one which was criticized by nations. Countries like the US and Germany did not welcome the idea of the treaty, so they refused to become members of the League. Also, the League of Nations ha no standing army to back it up. More so, some notable nations like the United States, Russia, Germany, etc. refused to join the League of Nations, thus this weakened League.