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During the 1920s, the League of Nations had a mixed record. It achieved some notable successes in settling disputes and improving social conditions, but it also experienced significant failures. This lesson examines the League's achievements and shortcomings in its first decade, providing the context for understanding its collapse in the 1930s.
The League successfully resolved several territorial and political disputes in the 1920s.
| Dispute | Date | Detail | Outcome |
|---|---|---|---|
| Aaland Islands | 1921 | Sweden and Finland both claimed these islands in the Baltic Sea | The League ruled in favour of Finland. Both countries accepted the decision |
| Upper Silesia | 1921 | Germany and Poland both claimed this industrial region | The League organised a plebiscite (vote). The region was divided between the two countries based on the results |
| Mosul | 1924 | Turkey claimed the province of Mosul, which had been given to the British mandate of Iraq | The League ruled in favour of Iraq. Turkey reluctantly accepted |
| Greece-Bulgaria | 1925 | Greek troops invaded Bulgaria after a border incident | The League condemned Greece and ordered it to withdraw and pay compensation. Greece obeyed |
Exam Tip: Notice that the League's successes in the 1920s involved smaller nations that were willing to accept its authority. When major powers were involved or unwilling to comply, the League struggled. This pattern is key to understanding its later failures.
The League's special commissions and agencies achieved significant successes in improving lives around the world.
| Agency/Commission | Achievement |
|---|---|
| Refugee Commission | Led by Fridtjof Nansen, it helped approximately 400,000 prisoners of war return home after WWI and provided the "Nansen Passport" for stateless refugees |
| Health Organisation | Worked to combat diseases such as malaria, leprosy, and typhus. Conducted research and ran vaccination campaigns |
| International Labour Organisation (ILO) | Campaigned against child labour, for maximum working hours, and for improved conditions. Successfully persuaded many countries to adopt reforms |
| Slavery Commission | Worked to end slavery and forced labour. Freed 200,000 slaves in Sierra Leone and challenged forced labour in Tanganyika |
| Mandates Commission | Supervised territories (former German and Ottoman colonies) administered by League members |
Exam Tip: The League's humanitarian work is often overlooked but is an important success story. In "How successful was the League?" questions, you should always discuss these achievements alongside the political disputes.
The League also experienced notable failures, particularly when major powers were involved.
| Dispute | Date | Detail | Outcome |
|---|---|---|---|
| Vilna | 1920 | Poland seized Vilna (the capital of Lithuania) by military force | The League protested but took no effective action. Poland kept Vilna. This demonstrated the League's inability to act against a determined aggressor supported by a major power (France backed Poland) |
| Corfu | 1923 | Italian general Tellini and four colleagues were assassinated on the Greek-Albanian border. Italy's Mussolini blamed Greece and bombarded and occupied the Greek island of Corfu | The League condemned Italy, but Mussolini refused to accept its authority. The Conference of Ambassadors (a separate body) intervened, and Greece was forced to pay compensation to Italy. The League was humiliated |
| Ruhr | 1923 | France and Belgium occupied Germany's Ruhr region when Germany defaulted on reparations payments | The League did nothing. Two of its leading members were the aggressors |
| Factors for Success | Factors for Failure |
|---|---|
| The countries involved were small and willing to accept the League's authority | Major powers (Italy, France, Poland) ignored the League when it suited them |
| No major power had a vital interest in the dispute | When major powers were involved, the League was powerless |
| The dispute could be settled through negotiation and compromise | Military aggression by a determined power could not be stopped without an army |
| The 1920s were a period of relative economic stability and goodwill (especially after Locarno, 1925) | The League had no enforcement mechanism — no army and weak sanctions |
Exam Tip: The Corfu Crisis is the most important failure of the 1920s. It showed that the League could not stand up to a major power (Italy) that was willing to use force. This was a warning of what would happen in the 1930s with Manchuria and Abyssinia.
The mid-to-late 1920s saw a period of improved international relations, sometimes called the "Locarno honeymoon" or the "spirit of Locarno."
| Development | Date | Significance |
|---|---|---|
| Dawes Plan | 1924 | Restructured German reparations; American loans stabilised the German economy |
| Locarno Treaties | 1925 | Germany accepted its western borders; created a mood of reconciliation |
| Germany joins the League | 1926 | A significant moment — the former enemy was now a member |
| Kellogg-Briand Pact | 1928 | 65 nations renounced war as a tool of foreign policy |
This period gave the impression that the League's system of collective security was working. However, this optimism was fragile and depended on continued economic prosperity and goodwill — both of which would be shattered by the Great Depression.
| Date | Event |
|---|---|
| 1920 | Vilna Crisis (Poland seizes Lithuanian capital) |
| 1921 | Aaland Islands dispute resolved; Upper Silesia plebiscite |
| 1923 | Corfu Crisis; French occupation of the Ruhr |
| 1924 | Dawes Plan; Mosul dispute resolved |
| 1925 | Locarno Treaties; Greece-Bulgaria dispute resolved |
| 1926 | Germany joins the League |
| 1928 | Kellogg-Briand Pact |
The League's humanitarian work in the 1920s was a genuine success of considerable scope, but its importance must be weighed against the resolution of territorial disputes, the mood of international cooperation symbolised by Locarno, and the structural limitations exposed by failures such as Corfu. The Refugee Commission under Fridtjof Nansen systematically repatriated approximately 400,000 prisoners of war after 1920 and issued the Nansen Passport to some 450,000 stateless persons. The Health Organisation conducted vaccination campaigns against typhus, leprosy, and malaria. The International Labour Organisation drafted 67 international conventions on working hours and child labour. The Slavery Commission freed an estimated 200,000 slaves in Sierra Leone. These achievements mattered because they demonstrated that international cooperation could produce concrete results and established institutional precedents that shaped the post-1945 United Nations system. However, the resolution of territorial disputes — the Aaland Islands (1921), Upper Silesia (1921), Mosul (1924), and the Greek-Bulgarian border incident (1925) — was arguably the more prominent political success, since these disputes involved the League's core peacekeeping function. The Locarno Treaties of October 1925, which formalised Germany's acceptance of its western borders and enabled German League membership in 1926, created the so-called "Locarno honeymoon" that seemed to validate the entire collective security project. The most sustained line of reasoning recognises that humanitarian work was the League's most durable legacy — its institutional DNA shaped the ILO and UNHCR — while its political successes depended on favourable conditions that would vanish in the 1930s. Therefore, humanitarian work was arguably most important in long-term significance, even if political disputes dominated contemporary perception.
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