Japanese Invasion of Manchuria

Setting the scene

Japan invaded Manchuria on September 18, 1931, following the Mukden Incident, a staged sabotage of the South Manchurian Railway near Mukden (Shenyang). Japanese officers of the Kwantung Army, seeking to justify expansion, planted explosives on the railway and blamed Chinese dissidents. Using this pretext, Japanese troops attacked Chinese forces and within months occupied all of Manchuria, a region three times the size of Japan with abundant resources and 30 million people.

What happened

The invasion was unauthorized by the civilian government in Tokyo, demonstrating the Japanese military's independence and dominance. The League of Nations sent the Lytton Commission to investigate, which concluded in 1932 that Japan had acted aggressively and recommended Manchuria be returned to China. Japan responded by withdrawing from the League in March 1933. In 1932, Japan established the puppet state of Manchukuo, installing Puyi, the last Qing emperor, as nominal ruler.

Why it still matters

The invasion of Manchuria marked the beginning of Japanese aggression in Asia and the collapse of collective security. It was the first major violation of the League of Nations covenant and the Kellogg-Briand Pact outlawing war. The West's weak response—verbal condemnation but no sanctions—emboldened Japan and later Hitler and Mussolini. The invasion began 14 years of war in China, leading to the Second Sino-Japanese War in 1937 and World War II in Asia. Manchuria became Japan's industrial base for further expansion, and the invasion is remembered in China as the start of the War of Resistance Against Japanese Aggression.

Background

The League could not reverse the aggression.