d) It was weakened by American refusal to join.
The League of Nations (SDN) or League of Nations was an international organization created by the Treaty of Versailles on June 28, 1919. It was proposed to establish the bases for peace and the reorganization of international relations once the First World War. Although it failed to solve the serious problems that arose in the 20s and 30s, it is important because it was the first organization of its kind in history and the antecedent of the UN.
The League of Nations achieved some success in its work, helped to peacefully resolve some conflicts in the immediate postwar period and had its peak in the period 1924-1929. During this period the Treaty of Locarno was signed in 1925, Germany joined the Society in 1926, and the Briand-Kellogg Pact was signed in 1928. However, when the international situation became turbulent after the 1929 depression, the League of Nations was totally incapable of maintaining peace.
The SDN was based on the principles of international cooperation, arbitration of conflicts and collective security. The Covenant of the SDN (the first 26 articles of the Treaty of Versailles) was drafted in the first sessions of the Paris Conference, which began on January 18, 1919, at the initiative of the President of the United States, Woodrow Wilson.
On November 15, 1920, the first assembly of the company was held in Geneva, with the participation of 42 countries.
After the end of the Second World War in the middle of the 20th century, the SDN was dissolved on April 18, 1946, and was succeeded by the United Nations (UN). In reality, it was not a succession of one international organization by another. The experience of the League of Nations is the closest thing to the current UN, but this precedent was not even mentioned by the drafters of the Charter since, in order to restructure the post-war world of the Second World War, the winning states opted to make the League of Nations disappear and create an entirely new international organization.