The League of Nations relied on collective security, members acting together against an aggressor, so it only worked if governments kept their promises.
The League of Nations began work in 1920. Its founding rules, the Covenant, set out ways to avoid war. Countries could discuss disputes, or ask a neutral body to judge them. This is arbitration. Members promised to respect each other's land and independence.
A country that went to war against the rules could face economic sanctions, where other countries cut trade and financial links with it. The League's Council could also ask governments to send troops. This was collective security. Members would act together, so an attacker would face many countries, not just its victim.
But the League had no army of its own. It depended on governments to provide troops and enforce sanctions. Many decisions needed unanimity, meaning all the members involved had to agree. Britain and France were the leading members, but acting against an aggressor could clash with their own money or security interests.
The USA never joined, so the League lacked the backing of a great power. Germany was kept out at first, but joined in 1926. So the League's rules mattered, but governments still had to choose to cooperate.
- 1920
- League of Nations begins work.
- Collective security
- Members act together against an aggressor.
- Weaknesses
- No army; USA never joined; decisions often needed all to agree.
Worked example: Why sanctions need everyone
Suppose members stop selling key goods to an aggressor, but other suppliers keep trading.
- Sanctions aim to make aggression costly.
- If others keep selling, the cost falls.
- So check who actually stopped trading before saying sanctions worked.
Watch out for this
The League could send its own army whenever a country attacked.
The League had no army. It depended on member governments to act.
Check your understanding
What was the League's biggest practical weakness?
- It had too many American troops.
- It banned arbitration.
- It had no army and relied on members to act.