Explain how the Japanese invasion of China led to the Second World War.

Japan’s ambitions grew after the First World War. Needing raw materials and markets for her expanding industries, she invaded MANCHURIA in 1931 and, despite the opposition of the League of Nations, occupied it and set up a puppet government there. She later began an undeclared war on China itself.

The significance lies in what did NOT happen. The League condemned Japan and sent the Lytton Commission, but when Japan simply walked out of the League in 1933 and kept Manchuria, no member was willing to use force.

This exposed the helplessness of the League and showed the world that aggression could go unpunished. It encouraged Mussolini to attack Abyssinia in 1935 and Hitler to violate the Treaty of Versailles openly — and that chain of unchecked aggression led directly to the Second World War.

The link the examiner wants is not "Japan was aggressive" but that the LEAGUE FAILED TO ACT, and that its failure emboldened others. Build the answer in three stages: what Japan did, what the League did (and did not) do, and what other dictators concluded. Naming the later examples — Abyssinia 1935, Hitler’s breaches of Versailles — is what turns a description into a CAUSE, which is exactly what the question asks for.