Manchukuo in the context of "Mukden incident"

Japan's Kwantung Army invaded the Manchuria region of China on 18 September 1931, immediately following the Mukden incident, a false flag event staged by Japanese military personnel as a pretext to invade. At the war's end in February 1932, the Japanese established the puppet state of Manchukuo. The occupation lasted until mid-August 1945, towards the end of the Second World War, in the face of an onslaught by the Soviet Union and Mongolia during the Manchurian Strategic Offensive Operation.

With the invasion having attracted great international attention, the League of Nations produced the Lytton Commission (headed by British politician Victor Bulwer-Lytton) to evaluate the situation, with the organization delivering its findings in October 1932. Its findings and recommendations that the Japanese puppet state of Manchukuo not be recognized and the return of Manchuria to Chinese sovereignty prompted the Japanese government to withdraw from the League entirely.

The Second Sino-Japanese War was fought between the Republic of China and the Empire of Japan between 1937 and 1945, following a period of war localized to Manchuria that started in 1931. It is considered part of World War II, and often regarded as the beginning of World War II in Asia. It was the largest Asian war in the 20th century. It is known in China as the War of Resistance Against Japanese Aggression.

On 18 September 1931, the Japanese staged the Mukden incident, a false flag event fabricated to justify their invasion of Manchuria and establishment of the puppet state of Manchukuo. This is sometimes marked as the beginning of the war. From 1931 to 1937, China and Japan engaged in skirmishes, including in Shanghai and in Northern China. Nationalist and Chinese Communist Party (CCP) forces, respectively led by Chiang Kai-shek and Mao Zedong, had fought each other in the Chinese Civil War since 1927. In late 1933, Chiang Kai-shek encircled the Chinese Communists in an attempt to finally destroy them, forcing the Communists into the Long March, resulting in the Communists losing around 90% of their men. As a Japanese invasion became imminent, Chiang still refused to form a united front before he was placed under house arrest by his subordinates who forced him to form the Second United Front in late 1936 in order to resist the Japanese invasion together.

The colonial expansion of the Empire of Japan in the Western Pacific Ocean and East Asia began in 1895 with Japan's victory over the Chinese Qing dynasty in the First Sino-Japanese War. Subsequent victories over the Russian Empire (Russo-Japanese War of 1904-1905) and the German Empire (World War I) expanded Japanese rule. Taiwan came under Japanese control from 1895, Korea in 1905, Micronesia in 1914, Southern Sakhalin in 1905, several concessions in China from 1903 onwards, and the South Manchuria Railway from 1905. In 1931, Japan invaded Manchuria, resulting in the establishment of the puppet state of Manchukuo the following year; thereafter, Japan adopted a policy of founding and supporting puppet states in conquered regions. These conquered territories became the basis for what became known as the Greater East Asia Co-Prosperity Sphere from 1940. (The Co-Prosperity Sphere expanded to include much of China, Indo-China, Malaya, the Philippines, the East Indies, Burma and New Guinea by 1942.)

Including Mainland Japan, colonies, occupied territories, and puppet states, the Empire of Japan at its apex was one of the largest empires in history. The total amount of land under Japanese sovereignty reached 8,510,000 km (3,300,000 sq mi) in 1942. By 1943, it accounted for more than 20% of the world's population at the time, with 463 million people in its occupied regions and territories.

The Greater East Asia Co-Prosperity Sphere (Japanese: 大東亜共栄圏, Hepburn: Dai Tōa Kyōeiken), also known as the GEACPS, was a pan-Asian union that the Empire of Japan tried to establish. Initially, it covered Japan (including annexed Korea), Manchukuo, and China, but as the Pacific War progressed, it also included territories in Southeast Asia and parts of India. The term was first coined by Minister for Foreign Affairs Hachirō Arita on June 29, 1940.

The proposed objectives of this union were to ensure economic self-sufficiency and cooperation among the member states, along with resisting the influence of Western imperialism and Soviet communism. In reality, militarists and nationalists saw it as an effective propaganda tool to enforce Japanese hegemony. The latter approach was reflected in a document released by Japan's Ministry of Health and Welfare, An Investigation of Global Policy with the Yamato Race as Nucleus, which promoted racial supremacist theories. Japanese spokesmen openly described the Greater East Asia Co-Prosperity Sphere as a device for the "development of the Japanese race." When World War II ended, the Greater East Asia Co-Prosperity Sphere became a source of criticism and scorn for the Allies.

Zhang Jinghui (traditional Chinese: 張景惠; simplified Chinese: 张景惠; pinyin: Zhāng Jǐnghuì; Wade–Giles: Chang Ching-hui; Hepburn: Chō Keikei; 21 June 1871 – 11 January 1959) was a Chinese general, warlord and politician during the Warlord era. He is noted for his role in the Japanese puppet regime of Manchukuo in which he served as Prime Minister for most of its existence.

The Kwantung Army (Japanese: 関東軍, Kantō-gun) was a general army of the Imperial Japanese Army from 1919 to 1945.

The Kwantung Army was formed in 1906 as a security force for the Kwantung Leased Territory and South Manchurian Railway Zone after the Russo-Japanese War of 1904–1905 and expanded into an army group during the interwar period to support Japanese interests in China, Manchuria, and Mongolia. The Kwantung Army became the most prestigious command in the Imperial Japanese Army, and many of its personnel won promotions to high positions in the Japanese military and civil government, including Hideki Tojo and Seishirō Itagaki. The Kwantung Army was largely responsible for the establishment and proxy control of the Japanese puppet-state of Manchukuo in Manchuria and functioned as one of the main Japanese fighting forces during the 1937–1945 Second Sino-Japanese War.

Manchuria is a historical region in northeast Asia encompassing the entirety of present-day northeast China and parts of the modern-day Russian Far East south of the Uda River and the Tukuringra-Dzhagdy Ranges. The exact geographical extent varies depending on the definition: in the narrow sense, the area constituted by three Chinese provinces of Heilongjiang, Jilin, and Liaoning as well as the eastern Inner Mongolian prefectures of Hulunbuir, Hinggan, Tongliao, and Chifeng; in a broader sense, historical Manchuria includes those regions plus the Amur river basin, parts of which were ceded to the Russian Empire by the Manchu-led Qing dynasty during the Amur Annexation of 1858–1860. The parts of Manchuria ceded to Russia are collectively known as Outer Manchuria or Russian Manchuria, which include present-day Amur Oblast, Primorsky Krai, the Jewish Autonomous Oblast, the southern part of Khabarovsk Krai, and the eastern edge of Zabaykalsky Krai.

The name Manchuria is an exonym (derived from the endonym "Manchu") of Japanese origin. The history of "Manchuria" (Manzhou) as a toponym in China is disputed, with some scholars believing it was never used while others believe it was by the late 19th century. The area was historically referred to by various names in the Qing dynasty such as Guandong (East of the Pass) or the Three Provinces referring to Fengtian (Liaoning), Heilongjiang, and Jilin. Manchuria as a geographical term was first used in the 18th or 19th centuries by the Japanese before spreading to Europe. The term was promoted by the Empire of Japan in support for the existence of its puppet state, Manchukuo. Although the toponym is still used, some scholars treat the term with caution or avoid it altogether due to its association with Japanese colonialism. The term is deprecated in China due to its association with Japanese imperialism and ethnic connotations. As a result, areas once considered part of Manchuria are simply referred to as the Northeast. The Three Provinces and the Northeast were also in concurrent use among the Japanese along with Manchuria until the Mukden incident of 1931.

The Soviet invasion of Manchuria, formally known as the Manchurian Strategic Offensive Operation or simply the Manchurian Operation (Маньчжурская операция) and sometimes, mainly in the West, as Operation August Storm, began on 9 August 1945 with the Soviet invasion of the Empire of Japan's puppet state of Manchukuo, which was situated in Japanese-occupied Manchuria. It was the largest campaign of the 1945 Soviet–Japanese War, which resumed hostilities between the Union of Soviet Socialist Republics and the Empire of Japan after almost six years of peace.

The invasion began hours before the atomic bombing of Nagasaki and 3 days after the atomic bombing of Hiroshima. The Soviet entry into this theater of the war and the defeat of the Kwantung Army were significant factors in the Japanese government's decision to surrender unconditionally on 15 August, as it became apparent that the Soviet Union had no intention of acting as a third party in negotiating an end of the war on conditional terms. The Kwantung Army officially surrendered on 16 August, although fighting continued until 2 September, when was firmed the Japanese Instrument of Surrender.