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The League of Nations (1920 – 1946) was the first intergovernmental organization established “to promote international cooperation and to achieve international peace and security”. It is often referred to as the “predecessor” of the United Nations.

Its founding document – the Covenant of the League of Nations – was drafted during the peace negotiations at the end of the First World War. It was composed of 26 articles, and covered many aspects of the organization, such as the conditions for membership, the functions of the principal organs, the mechanisms for a peaceful settlement of international disputes, and the obligations of the Member States. The Covenant also contained the main principles on which the League was built.


The creation of the League of Nations marked a new era of multilateral cooperation. The Covenant bound its Member States to try to settle their disputes peacefully. By joining the League, Member States also renounced secret diplomacy, committed to reduce their armaments, and agreed to comply with international law. Each state pledged to respect the territorial integrity and political independence of all members of the League. By establishing a bond of solidarity between Member States, the League is considered the first attempt to build a system of collective security. This principle relied on a simple idea: an aggressor against any Member State should be considered an aggressor against all the other Member States.

The League of Nations was also in charge of supervising the Mandate system. The “mandated territories” were former German colonies and Ottoman territories placed under what the Covenant called the “tutelage” of mandatory powers until they could become independent states.

Although the Covenant focused on conflict prevention and the peaceful settlement of disputes, some articles referred to the role of the League in promoting international cooperation in areas such as health, drug trafficking, transit, freedom of communications, and human trafficking. The efforts in these fields became increasingly important over the years and, in some cases, paved the way for the creation of United Nations entities, such as Specialized Agencies and UN Funds and Programmes.

Some responsibilities were assigned to the League by other international instruments, such as the peace treaties signed in Paris. In 1920, the Saar territory was placed under the League’s administration until a plebiscite was held to decide on its future. The League also supervised the Constitution of the Free City of Danzig and the implementation of the minority treaties. The treaties were signed after the Peace Conference in Paris and drastically changed the borders in Europe.



The League of Nations officially came into existence on 10 January 1920. On 15 November 1920, 41 members states gathered in Geneva for the opening of the first session of the Assembly. This represented a large portion of existing states and corresponded to more than 70% of the world’s population.

Officially, the League was an organization with a universal vocation. The organization was open to “any fully self-governing State, Dominion or Colony”, providing they fulfilled certain requirements and obtained a two thirds majority of votes in favor of their admission. In total, 63 states became members of the League of Nations (with at most 60 at the same time), which represents a great majority of the states existing at that time. However, the League never succeeded to become a truly universal organization. For instance, the United States never joined the organization, and a large part of the world remained under colonial rule.

Additional Information

The UN Archives Geneva Platform allows to navigate and search about 10 linear kilometers of archives, managed by the UN Library & Archives Geneva, which include different collections such as the 19th century peace movements, the League of Nations, the UN Geneva and different UN entities based in Geneva.

The League of Nations Archives are registered on the UNESCO’s Memory of the World Register which lists documentary heritage of outstanding value. Thanks to the LONTAD Project, the entirety of the League of Nations Archives will be available online. This represents almost 15 million pages, 15,000 maps and 3,000 photographs.

Do not hesitate to consult the research guides prepared by UN Library & Archives Geneva if you want more information and resources.