The League of Nations: Structure and Membership
A New Idea: Collective Security
When Wilson’s Fourteen Points called for a ‘general association of nations’, he was proposing something the world had never tried. The idea, set out in the League’s founding document — the Covenant — was collective security: aggression against any member would be treated as aggression against all, deterring war by threatening combined response. The Covenant formed the first 26 articles of the Treaty of Versailles. It came into force on 10 January 1920, the day the treaty took effect. The League worked from London at first and moved its headquarters to Geneva in November 1920.
The League of Nations came into being on 10 January 1920 and moved to its Geneva headquarters in November 1920. Its founding document was the Covenant. Its core principle was collective security — that an attack on one member would be met by all.
The Bodies of the League
The League had four main parts. The Council was a small executive body for handling disputes. It originally had four permanent members — Britain, France, Italy and Japan — and four (later more) non-permanent members elected by the Assembly. The Council met three times a year and in emergency sessions. The Assembly was the parliament of the League, with all member states represented. Each state had one vote, regardless of size. The Assembly met annually and dealt with budgets, admitting new members and broad policy.
A common student error is to confuse the two: think of the Council as the engine room and the Assembly as the debating chamber. Both, fatally, required unanimity for major decisions, meaning a single member could veto action. Behind these political bodies sat the Secretariat (the civil service, headed by a Secretary-General) and the Permanent Court of International Justice (the legal arm, based in The Hague).
Beyond political dispute resolution, the League ran a network of specialist agencies that did real work for ordinary people. The International Labour Organization (ILO) lobbied for shorter hours, fairer pay and bans on child labour. The Health Committee tackled cholera, malaria and leprosy and laid foundations for what became the World Health Organization. The High Commission for Refugees, led from 1921 by Norwegian explorer Fridtjof Nansen, helped resettle hundreds of thousands of people displaced by the war and the Russian Civil War. The League’s Slavery Commission worked to end the slave trade in Africa, and Mandate Commissions monitored the territories taken from Germany and the Ottomans. These agencies were among the League’s most lasting successes — they outlived the League itself, becoming the basis of much of the modern UN system.
The Powers of the League
When a member broke the rules, the League had three escalating responses. First came moral condemnation — a public statement that the aggressor was in the wrong. Second, economic sanctions — cutting off trade or finance. Third, in theory, military force — member states would contribute troops to enforce League decisions. In practice, the third option was almost never used because the League had no army of its own and members had no obligation to send troops.
This made the League essentially a discussion forum backed by economic threat. Where great powers were the aggressors and willing to bear sanctions, there was little the League could do.
Membership: A League of Missing Powers
The League launched with 42 members in 1920. By the late 1920s membership rose past 50, and by 1934 it reached 58. But the membership story is largely a story of missing or temporary great powers.
The United States, despite Wilson’s leading role in designing the League, never joined — the Senate refused to ratify the Treaty of Versailles in 1919-20. The Soviet Union was excluded as ideologically hostile after the 1917 Bolshevik Revolution; it would not join until 1934, only to be expelled in 1939 for invading Finland. Germany was excluded as a defeated outlaw and only joined in 1926, after the rehabilitation of Locarno and Stresemann’s reconciliation diplomacy. In 1933, the year Hitler came to power, Germany resigned from the League; Japan resigned the same year over the Manchurian crisis. Italy left in 1937 after invading Abyssinia. By 1939 the League’s great-power membership was effectively just Britain and France.
The USA never joined the League. Germany joined 1926, left 1933. Japan founding member, left 1933. The USSR joined 1934, expelled 1939. By 1939 the only remaining great-power members were Britain and France.
Eric Drummond and the Civil Service
The League’s first Secretary-General, the British diplomat Eric Drummond, served from 1920 to 1933. He built the Secretariat into a genuinely international civil service, recruiting staff loyal to the League rather than their home states. This was a quiet but important innovation: it created the model for the UN civil service that followed in 1945. Drummond’s low-key style worked well in the 1920s when the League was fighting for legitimacy, but the system would prove no match for great-power aggression in the 1930s.