On the night of September 18, 1931, Kwantung Army Lieutenant Suemori Kawamoto set off a small explosive on a small section of the South Manchuria Railway line near Mukden. The explosion caused only minor damage to the rail track and a Mukden-bound train passed through it later without encountering any difficulty. Kwantung Army conspirators, led by officers Itagaki and Ishiwara, initiated this action, which historically is called the Mukden Incident, in order to accuse the Chinese of armed provocation and thereby justify a Japanese military reaction that would lead to a full-scale conquest of Manchuria.
(Taken from Japanese Invasion of Manchuria – Wars of the 20th Century – Twenty Wars in Asia: Vol. 5)
Immediately following the Mukden Incident, on Colonel Itakagi’s orders, Japanese forces attacked the Chinese Army garrison at Mukden. The 7,000-man garrison Chinese force did not resist the 500 Japanese attackers, but fled their garrison and Mukden. Col. Itakagi also mobilized Japanese forces all across the 1,100-km long South Manchuria Railway and as per the pre-arranged plan, moved to seize towns and cities throughout Manchuria.
In Ryojun (Port Arthur), Kwantung Army commander General Honjo was infuriated that junior officers had initiated military action without his approval. But after being counseled by Col. Ishiwara and the other conspirators, General Honjo was won over, and immediately requested more troops to be brought in from Korea. A few hours after the start of hostilities, on September 19, 1931, General Honjo transferred the Kwantung Army headquarters to Mukden, which by now was under full Japanese control.
Within a few days, Japanese forces seized much of Liaoning and Kirin (Jilin) provinces, including virtually all regions, towns, and cities such as Anshan, Haicheng, Kaiyuan, Tieling, Fushun, Changchun, Yingkou, Antung, Changtu, Liaoyang, Kirin, Chiaoho, Huangkutun, and Hsin-min. In Tokyo, the central government was stunned by this latest act of gekokujō (military insubordination, which was widespread among junior officers), but gave its consent and sent more Japanese troops to Manchuria to support the Kwantung Army’s spectacular successes.
Thereafter, Japanese military authorities successfully co-opted many Chinese military commanders (including Generals Xi Qia, Chang Ching-hui, and Chang Hai-peng), warlords, and officials to form local and provincial administrations in the various jurisdictions, replacing the deposed pro-KMT governments. By October 1931, many such pro-Japanese local governments had been established in Kirin (Jilin) and Liaoning provinces. The Japanese conquest of southern Manchuria was completed in early January 1932 with the capture of Chinchow (Jinzhou) and Shanhaiguan, with Chinese forces offering no resistance and withdrawing south of the Great Wall into Hebei Province.
Earlier in October 1931, pro-Japanese General Xu Jinglong led an army north to take Heilongjiang Province, but met strong resistance at the Nen River crossing near Jiangqiao. But with the support of Japanese troops that protected work crews repairing the bridge, the attack soon broke through and by November 18, 1931, Tsitsihar (Qiqihar), the provincial capital, was taken, with loyalist General Ma Zhanshan and his troops escaping to the east of Heilongjiang Province. Following the conquest of southern Manchuria, Japanese authorities tried to win over through negotiations Ma Zhanshan and the other defiant northern KMT commander, General Ting Chao, but failed. Japanese forces then launched an offensive to take Harbin, the last KMT stronghold in Manchuria, which fell in early February 1932. In this battle, the Japanese came to the assistance of their collaborationist Chinese allies whose attack earlier had been thrown back by loyalist Chinese forces.
To provide legitimacy to its conquest and occupation of Manchuria, on February 18, 1932, Japan established Manchukuo (“State of Manchuria”), purportedly an independent state, with its capital at Hsinking (Changchun). Puyi, the last and former emperor of China under the Qing dynasty, was named Manchukuo’s “head of state”. In March 1934, he was named “Emperor” when Manchukuo was declared a constitutional monarchy.
Manchukuo was viewed by much of the international community as a puppet state of Japan, and received little foreign recognition. In fact, Manchukuo’s government was controlled by Japanese military authorities, with Puyi being no more than a figurehead and the national Cabinet providing the front for Japanese interests in Manchuria.
Beset by internal turmoil, Chang Kai-shek’s Nationalist government in Nanjing was unable to military oppose the Japanese invasion, for a number of reasons. First, in the period after reunifying China in 1928, Chiang struggled to maintain control of the country, as large parts of China remained de facto autonomous and were dominated by powerful warlords who pledged only nominal allegiance to the central government. Second, even Chiang’s own government was racked by power struggles, and political rivals tried to set up alternative regimes in other parts of the country. Third, Chiang also faced a growing communist insurgency (under the Communist Party of China), which in the years ahead, would become a major threat to his authority. To confront these domestic problems and also deeming that China was yet military incapable of facing Japan in war, Chiang adopted the policy of “First internal pacification, then external resistance”, that is, first, defeat the communists, warlords, and political rivals, and then confront Japan.
China sought international diplomatic support. On September 19, 1931, one day after the start of hostilities, it appealed to the League of Nations to exert pressure on Japan. On September 22, the League called on the two sides to resolve their disputes peacefully. But with Japan continuing armed action, on October 24, 1931, the League passed a resolution demanding that Japanese forces withdraw from Manchuria by November 16, which was rejected by the Japanese government.
The League then formed the investigative Lytton Commission (named after the British administrator Victor Bulwer-Lytton, 2nd Earl of Lytton), which arrived in China in January 1932, to determine the causes of the conflict. In October 1932, the Lytton Commission released a report, whose findings included the following: that Japan was the aggressor and its claim of acting in self-defense was untrue; and that China’s anti-Japanese policies and rhetoric, and refusal to compromise, aggravated the crisis. No mention was made of the side responsible for causing the Mukden Incident. The Commission also refused to recognize Manchukuo, stating that it did not come from a “genuine and spontaneous independence movement”. In February 1933, the League of Nations approved the Lytton Commission’s report; the following month, Japan revoked its membership in the League and left.