1914-1918WW1, known as the Great War was a devestating event, resulting in 20 million casualities and 20 million injured personnel. In 1918, Germany surrendered and were forced to sign the Treaty of Versailles
The Big Three, known as Woodrow Wilson, Lloyd George and Georges Clemenceau met at the Palace of Mirrors in the Palace of Versailles to sign the Treaty of Versailles. They all wanted to make Germany pay, such as reducing their army, implementing trade sanctions, etc.
The big 3 debated and discussed about different points to add. Woodrow Wilsion himself prepared 14 points for the Treaty of Versailles, one of which was the creation of The League of Nations, a diplomatic organisation that would solve disputes, fight world problems and to encourage disarmement.
On 10th January 1920, the League of Nations was finally formed. Around 40-50 countries joined the LON just in 1920. The aim of the LON was to maintain peace and security, improve living and working conditions and encourage disarmement and co-operation.
The American Senate and the people refused to join the LON as they wanted to focus on their own development. They didn't want to suffer anymore and didn't want to be a part of anything again. Other powers, like Russia did not join the LON as well, which was why the LON was so weak.
On 20th April, 1946, the League of Nations officialy ended. They were a huge failure and were unable to prevent WW2, which caused many more casualties and destruction.