The Mukden Incident gave justification for the latter Japanese actions in Manchuria and its conquering.
The Mukden Incident, also known as the Manchurian Incident, is a staged attack on Japanese business in China. The staged act was setting an explosive next to a Japanese owned railway in Manchuria. The explosion was very weak, and didn't even caused any damage to the railway, it was more like an explosion of a bigger firecracker.
The Japanese though, stages this with a purpose of having an excuse to attack China, and so they did. The Japanese officials blamed China for the ''attack'', so as a response the Japanese attacked Manchuria and managed to conquer it as they planned.
