One theme of this breadth study is policing conflict: how far an international organisation could settle quarrels between countries without war. In the 1920s the League of Nations had some real successes. This lesson looks at three of them. In each one, remember that the League had no army, so it relied on persuading countries to accept its decision.
The Aaland Islands, 1920-21
The Aaland Islands lie in the sea between Finland and Sweden. Finland had become independent from Russia in 1917 and controlled the islands. Most islanders spoke Swedish and wanted to join Sweden. Finland refused to give them up, and both countries talked of using force.
In 1920 Britain referred the dispute to the League. The League investigated and listened to both sides. In 1921 it decided that the islands should stay part of Finland, but with autonomy and with protection for the islanders' Swedish language and customs. The islands were also to be demilitarised, so they could not be used to threaten Sweden.
Why it worked: Finland and Sweden were both small countries with no wish to fight. Both were League members and both accepted the ruling. The decision gave each side something: Sweden got guarantees for the islanders and safety from a fortified neighbour, and Finland kept the land. No Great Power had a strong interest of its own to protect, so none stood in the way.
Upper Silesia, 1921
Upper Silesia was a region rich in coal mines and heavy industry. After the First World War, the Treaty of Versailles said its people should vote in a plebiscite on whether to belong to Germany or to Poland. The vote was held in March 1921. Germany won more votes overall, but Polish speakers formed the majority in many districts. Fighting broke out, with Polish uprisings and German armed groups clashing in the area.
The Allied governments could not agree a solution, so the matter was handed to the League. The Council asked a committee of experts from countries not involved in the dispute to study the area. In October 1921 the Council divided the region. Germany kept the larger share of the land, but most of the coal mines and heavy industry went to Poland. In 1922 Germany and Poland also signed an agreement to protect the rights of minorities living on each side of the new border.
Why it worked: the League used neutral experts and a fair compromise, and both Germany and Poland accepted the result. Germany, a defeated country, did not yet have the strength to resist. The Great Powers on the Council backed the decision, and the League was handed the problem because the Allies themselves were stuck.
The Greek-Bulgarian War, 1925
In October 1925 there was a shooting on the border between Greece and Bulgaria, and a Greek soldier was killed. The Greek army then invaded Bulgaria. Bulgaria did not fight back. Instead it appealed to the League.
The Council met quickly. Its chairman, the French foreign minister Aristide Briand, called on both sides to stop fighting and pull back their troops. The Council sent a commission to investigate. It found Greece to blame and ordered it to pay Bulgaria £45,000 compensation. Greece withdrew its army and paid.
Why it worked: it was a quick response to a small war. Bulgaria, which had been on the losing side in the First World War, was weak and trusted the League. Britain and France, the two strongest League members, backed the Council's demand. Greece was a small country, which could not stand up to pressure from the Great Powers, and it had no wish to be seen as an aggressor.
What the three cases have in common
✅ Why the League succeeded
The countries were small or weak and accepted the League's decision. Finland, Sweden, Greece and Bulgaria were members; Germany was not yet a member in 1921, but the Allies handed it the problem. The Great Powers supported the decision, and none of them had a big interest of its own in the outcome.
📝 What the League did
It listened to both sides, sent investigators or commissions, called for a stop to fighting and proposed a settlement that each side could accept.
Change and continuity
These successes came in the 1920s, when the Great Powers were willing to back the League. A later lesson shows how things changed in the 1930s, when stronger countries ignored it. Notice that in all three cases the League only succeeded because the countries involved chose to obey.
Common mistakes
Common mistakes
- Writing "the League solved it" without saying what it did. Name the action, such as the commission, the ruling or the compensation.
- Mixing up the cases. Aaland stayed with Finland, Upper Silesia was divided, and Greece paid Bulgaria.
- Saying the League used force. In none of these cases did it use an army.
- Giving a "why it worked" that applies to every case. Use facts specific to each dispute.
Exam-style question
Explain TWO causes of the League of Nations' success in settling disputes in the 1920s. [8 marks]
Model answer
One cause was that the countries involved were small or weak and accepted the League's decisions. In the Aaland Islands dispute of 1920-21, Finland and Sweden were both League members and neither wanted a war. When the League ruled in 1921 that the islands should stay with Finland, with autonomy for the islanders and demilitarisation, both accepted. In 1925 Bulgaria, a weak country, appealed to the League rather than fight, and Greece withdrew and paid £45,000 compensation. The League could settle these disputes because the countries chose to obey.
A second cause was that the League handled the disputes fairly and, in 1925, quickly, with the support of Britain and France. In Upper Silesia the Council used a committee of experts from neutral countries and in October 1921 divided the region, with most of the coal mines going to Poland and Germany keeping the larger share of the land. Both Germany and Poland accepted this compromise. In 1925 the Council, chaired by Briand, met quickly and demanded that the fighting stop. Because the two strongest members backed the demand, Greece complied, and a small war ended.
What lifts this to the top level: two different causes, each supported by precise facts from more than one dispute, and a clear explanation of how each cause led to success.
Exam tip
Give two separate causes in two paragraphs. One cause alone cannot score more than half marks. Pick a cause, support it with dates and facts from a dispute, then say how it led to the League's success.
Recap
- Aaland Islands (referred 1920, settled 1921): the islands stayed Finnish, with autonomy, and were demilitarised.
- Upper Silesia (1921): after a plebiscite and violence, the League divided the region; Poland received most of the industry.
- Greek-Bulgarian War (1925): the Council demanded a halt, Greece withdrew and paid £45,000 compensation.
- The League succeeded when small countries accepted its authority and the Great Powers backed it.