The League of Nations was an international organization created in 1920 after World War I to keep peace through collective security and diplomacy; in AP World, it matters as a cause of WWII (it failed to stop aggression) and as the flawed predecessor of the United Nations.
The League of Nations was the world's first major attempt at a permanent international peacekeeping organization. It came out of the Paris Peace Conference and the Treaty of Versailles in 1920, built on the idea of collective security, meaning if one member got attacked, the others would respond together so no aggressor could win. The League also pushed disarmament and tried to settle disputes through negotiation instead of war.
Here's the catch, and it's the part AP World cares about most. The League had no army of its own, the United States never joined (despite Woodrow Wilson basically inventing the idea in his Fourteen Points), and its strongest tool was economic sanctions that members often ignored. When Japan invaded Manchuria in 1931 and Italy invaded Ethiopia in 1935, the League condemned the aggression but couldn't stop it. Aggressors learned the lesson fast. The League also ran the mandate system, which handed former German and Ottoman territories to Britain and France to administer. In practice, that was imperialism with new paperwork, and it fueled anti-imperial resistance across Africa, the Middle East, and Asia.
The League shows up across two units. In Unit 7, it's central to Topic 7.5 (Unresolved Tensions After World War I) and Topic 7.6 (Causes of World War II). The CED's essential knowledge for 7.6.A names the "unsustainable peace settlement after World War I" as a cause of WWII, and the League is the institutional face of that settlement. Its failure to enforce collective security is exactly the kind of cause you weigh under 7.9.A when explaining the relative significance of causes of global conflict. The mandate system also supports 7.5.A, since the transfer of former German colonies to Britain and France through League mandates is listed essential knowledge on territorial continuity.
In Unit 9, the League is the backstory for 9.8.A. The United Nations and other postwar institutions were designed with the League's failures in mind. If you can explain why the UN got a Security Council with enforcement power and US membership, you're really explaining what the League lacked. That's a continuity-and-change argument the exam loves.
Keep studying AP World Unit 7
Treaty of Versailles (Unit 7)
The League was created by the Treaty of Versailles, so they share a fate. The same harsh, unstable peace settlement that the CED calls "unsustainable" also produced the organization that was supposed to defend it, and both collapsed under the pressure of the 1930s.
United Nations (Unit 9)
The UN is essentially League of Nations 2.0 with the bugs patched. After 1945, the new organization got US membership and a Security Council that could authorize real force, fixing the two biggest reasons the League failed. This is a classic continuity-and-change pairing for essays.
Collective Security (Unit 7)
Collective security was the League's whole operating theory, an attack on one is an attack on all. The League proves the idea only works if members actually enforce it, which is why Manchuria and Ethiopia are the go-to evidence that the theory broke down in practice.
Anti-Imperial Resistance (Unit 7)
The League's mandate system handed former German and Ottoman territories to Britain and France, which looked a lot like colonialism rebranded. That hypocrisy fed anti-imperial movements like the Indian National Congress and West African strikes and congresses, both named in the CED.
Multiple-choice questions usually test the League through its failures. A common stem asks what Japan's invasion of Manchuria demonstrated about the League, and the answer is that collective security was toothless without enforcement power or universal membership. You might also see counterfactual reasoning, like what would have changed if Wilson's Fourteen Points had been fully adopted, or comparison questions linking interwar instability to nationalism in other periods.
No released FRQ has used the term verbatim, but the League is high-value FRQ evidence in two directions. For a causation essay on WWII (7.6, 7.9), the League's weakness is concrete evidence that the postwar settlement couldn't contain fascist aggression. For a continuity-and-change essay on international institutions (9.8), the League-to-UN arc is a ready-made argument about how globalization changed interactions among states. Don't just say the League "failed." Explain the mechanism, no army, no US, sanctions nobody enforced.
The League of Nations (1920) came after WWI; the United Nations (1945) came after WWII and replaced it. The big differences are membership and muscle. The US never joined the League, and the League had no real enforcement power, while the UN included the US from day one and gave its Security Council the authority to back resolutions with force. On the exam, the League belongs in Unit 7 arguments about the causes of WWII, while the UN belongs in Unit 9 arguments about globalization and international cooperation.
The League of Nations was founded in 1920 after World War I to maintain peace through collective security, disarmament, and diplomatic dispute resolution.
The United States never joined the League, which crippled it from the start since the world's rising power wasn't bound by its decisions.
The League's failure to stop Japan in Manchuria (1931) and Italy in Ethiopia (1935) showed aggressors that collective security wouldn't be enforced, helping cause World War II.
The League's mandate system transferred former German colonies to Britain and France, continuing imperial control under a new name and sparking anti-imperial resistance.
The United Nations was designed in 1945 to fix the League's flaws, with US membership and a Security Council that had real enforcement power.
On the exam, use the League as evidence for the 'unsustainable peace settlement' cause of WWII in Unit 7 and as the predecessor to the UN in Unit 9.
The League of Nations was an international organization founded in 1920 by the Treaty of Versailles to prevent another world war through collective security, disarmament, and diplomatic resolution of disputes. It grew out of Woodrow Wilson's Fourteen Points after WWI.
Three big reasons. The US never joined, the League had no military force of its own, and its economic sanctions were rarely enforced. When Japan invaded Manchuria in 1931 and Italy invaded Ethiopia in 1935, the League condemned both but stopped neither.
No. Even though President Wilson championed the idea, the US Senate rejected the Treaty of Versailles and the US returned to isolationism. American absence is one of the main reasons the League couldn't enforce its decisions.
The League (1920) followed WWI and failed; the UN (1945) followed WWII and replaced it. The UN fixed the League's biggest flaws by including the US as a founding member and giving its Security Council real enforcement power. For AP World, the League is Unit 7 material and the UN is Unit 9.
No, mostly the opposite. The mandate system transferred former German and Ottoman territories to Britain and France to 'administer,' which in practice extended imperial control between the wars. The CED lists this transfer as a territorial continuity, and it fueled anti-imperial resistance movements.