After the First World War, everyone wanted to avoid repeating the mass slaughter of the war which had just ended. They also agreed that a League of Nations, an organisation that could solve international problems without resorting to war, would help achieve this.
President Wilson wanted the League of Nations to be like a world parliament where representatives of all nations could meet together regularly to decide on matters which affected them all. In 1918 he quoted, "Merely to win a war was not enough. It must be won in such a way as to ensure the future peace of the world." By February he had drafted a very ambitious plan, which would contain all of the following; all major nations would join the League, they would disarm and if they had a dispute with another country, they would take it to the League. They promised to accept the decision made by the League and to protect one another if they were invaded. If any member did break the covenant and go to war, other members would stop trading with it and send troops if necessary to force it to stop fighting. .
Most people in Europe were prepared to give Wilson's plans a try. They hoped that no country would dare invade another if they knew the USA and other powerful nations of the world would stop trading with them or send armies to stop them. However, in America, the idea of a League was not very popular and Woodrow Wilson needed the approval of his Congress. The Republicans campaigned for America to be isolationist and it won. So, when the League opened for business in January 1920, the American chair was empty and it never joined. This was a huge blow to the League.
The covenant set out the League's aims which included, to discourage aggression from any nation, to encourage countries to cooperate, especially in business and trade and to encourage nations to disarm.
The League and its collective security policy were very successful in settling border disputes during the 1920's.