Mukden incident

Late on 18 September 1931, a small charge of dynamite went off beside a Japanese-owned railway line just outside Mukden, today's Shenyang, in north-east China. Officers of Japan's Kwantung Army had planted it themselves, blamed Chinese troops, and used the blast as the excuse for seizing all of Manchuria. The episode led to the puppet state of Manchukuo, Japan's departure from the League of Nations and, in the eyes of many historians, the first step towards war between China and Japan.

Japan's foothold in Manchuria dated from the Russo-Japanese War of 1904–1905, after which it leased the South Manchuria Railway and stationed soldiers along it as railway guards. As the Nationalist government of Chiang Kai-shek tried to restore Chinese authority after years of warlord rule, it began to challenge Japanese treaty rights. The Manchurian warlord Zhang Zuolin had been assassinated by the Kwantung Army, and his son Zhang Xueliang aligned himself with Nanjing. A short war in 1929 in which the Soviet Union defeated Zhang's troops exposed Chinese military weakness and also worried Japanese planners about growing Soviet strength.

Two Kwantung Army staff officers, Colonel Itagaki Seishirō and Lieutenant Colonel Ishiwara Kanji, decided to manufacture a pretext for conquest. Their plans were complete by the end of May 1931. They chose a stretch of track near Liutiao Lake, some 800 metres from the Chinese barracks at Beidaying. At about 22:20 on 18 September, Lieutenant Kawamoto Suemori's men set off the explosives. The damage was so slight that a train from Changchun passed over the spot a few minutes later.

The Japanese immediately accused Chinese soldiers of the attack. Artillery shelled the Beidaying garrison, and by the evening of 19 September Japanese troops held Mukden; Chinese losses were reportedly around 500, against two Japanese dead. The Kwantung Army commander, General Honjō Shigeru, had not authorised the operation but endorsed it afterwards, and reinforcements came in from Korea. Zhang Xueliang ordered his forces not to resist, and Japanese troops quickly took Changchun and other cities. Despite resistance from some provincial commanders, within about five months the Japanese controlled the major towns of all three north-eastern provinces.

China appealed to the League of Nations on 19 September. The League called for a Japanese withdrawal, but Japan refused. In January 1932 the United States announced the Stimson Doctrine, refusing to recognise any regime created by Japanese action in Manchuria. In March 1932 Japan set up Manchukuo, with the last Qing emperor, Puyi, as its figurehead. The League's Lytton Report, published that October, rejected Japan's claim to have acted in self-defence and described Manchukuo as the product of military aggression. Japan left the League in March 1933.

The post-war evidence that the bomb was a Kwantung Army plot is strong, and Japanese as well as Chinese institutions now accept this. Historians still debate how far the officers acted alone: some stress their insubordination, while others argue that senior commanders tacitly allowed it and that civilian leaders shared their aims. In China the incident is remembered every 18 September with air-raid sirens, and since 2017 the Communist Party has dated the start of its war of resistance against Japan to 1931 rather than to 1937, when the full Second Sino-Japanese War began.

Our 1930 map shows Manchuria as part of the Republic of China, and our 1938 map shows it after its seizure by the Empire of Japan.