By 1937, China was already divided between Guomindang government forces and Mao Zedong's communists in the north-west. Japan's full-scale invasion in July 1937 changed everything — it forced China's two rival armies into an uneasy Second United Front, but it also devastated the country and reshaped the balance of power between Nationalists and communists.
Why the war mattered for who ruled China: The Sino-Japanese War (1937–1945) did not just cost millions of lives. It weakened the Guomindang while strengthening the communists — which is exactly why the war is central to explaining the communist victory in 1949.
- Nanjing Massacre (December 1937) — Japanese troops killed tens of thousands of civilians and soldiers after capturing the Nationalist capital; it showed the brutality of the occupation and hardened Chinese resistance.
- Guomindang retreat — Jiang Jieshi moved his government inland to Chongqing; his forces bore the brunt of costly conventional battles against Japan and suffered huge losses of trained troops and territory.
- Communist strategy — from their base at Yan'an, the communists fought a smaller-scale guerrilla warfare campaign, avoided the worst Japanese offensives, and used the time to expand into rural areas Japan did not fully control.
- Mass mobilisation — communist land policies (rent reduction, not full redistribution, to keep the United Front) won peasant support in the areas they controlled, growing the party from about 40,000 members in 1937 to over a million by 1945.
When Japan surrendered in August 1945, both sides raced to accept Japanese surrenders and seize territory — especially in Manchuria, where Soviet forces had just defeated the Japanese Kwantung Army and handed over huge stockpiles of weapons to the communists.
1946 — Civil war resumes
Talks between Jiang Jieshi and Mao Zedong (brokered partly by the USA) collapsed. Full-scale civil war broke out across China, with the Guomindang initially holding more territory and US support.
1947–48 — The tide turns
Communist forces (renamed the People's Liberation Army) won major victories in Manchuria and the north. Guomindang armies, poorly led and demoralised by corruption and hyperinflation, surrendered or defected in large numbers.
1949 — Communist victory
The PLA captured Beijing, Nanjing and Shanghai. On 1 October 1949, Mao Zedong proclaimed the People's Republic of China in Beijing. Jiang Jieshi fled to Taiwan.
War weakened the Guomindang, strengthened the communists, and the 1945–1949 civil war finished the job.
| Factor | Guomindang weakness | Communist strength |
|---|---|---|
| Political | Corruption; loss of public trust; harsh treatment of civilians in reconquered areas | Land policy and discipline won peasant loyalty in the countryside |
| Economic | Hyperinflation destroyed savings and wages in cities | Simpler rural economy less exposed to currency collapse |
| Military | Best troops destroyed fighting Japan 1937–1945; low morale; desertion | Guerrilla experience; captured Japanese weapons via Soviet handover in Manchuria; PLA discipline |
For Paper 3 essays: Examiners reward linking the war to the civil war outcome — do not describe them as two separate stories. Show how 1937–1945 caused the conditions (weak Guomindang, strong communists, Manchuria's weapons) that decided 1946–1949.
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Japan formally annexed Korea in 1910, ending Korean independence. For 35 years, Korea was ruled directly from Tokyo as a colony — its people lived under a harsh occupation that intensified sharply once Japan went to war with China in 1937.
Social, political and economic effects of annexation
- Political control — the Korean monarchy was abolished; a Japanese Governor-General ruled with wide police powers; Korean political parties and newspapers were banned or tightly censored.
- Cultural suppression — Japan pushed assimilation policy, trying to erase Korean identity: the Korean language was restricted in schools, Korean history was rewritten, and Koreans were later pressured to adopt Japanese names.
- Economic exploitation — Japan restructured Korea's economy to serve Japanese needs: land surveys transferred ownership to Japanese settlers and companies, and rice was exported to Japan even during Korean food shortages.
- Early resistance — the March 1st Movement (1919), inspired partly by the same self-determination ideas behind China's May Fourth Movement, saw mass peaceful protests across Korea; Japan crushed it violently but eased some policies afterwards.
The impact of the Sino-Japanese War on Korea (after 1937): Once Japan was fighting a full war in China, Korea was squeezed even harder to supply Japan's war machine.
Forced labour
Hundreds of thousands of Koreans were conscripted to work in Japanese mines, factories and construction projects, often in brutal conditions far from home.
Military conscription
From 1938, and compulsorily from 1944, Korean men were drafted into the Japanese military, fighting and dying in a war for the country that had colonised them.
"Comfort women"
Tens of thousands of Korean women and girls were forced into sexual slavery for the Japanese military — one of the most painful and contested legacies of the occupation.
Japan's sudden surrender in August 1945 left a power vacuum in Korea. Soviet troops entered from the north and US troops landed in the south — with no Korean government yet re-established, the two victors agreed to divide the peninsula for the practical purpose of accepting the Japanese surrender.
Division at the 38th parallel (1945): The 38th parallel was chosen almost arbitrarily by US planners as a line to split occupation duties with the USSR. It was meant to be temporary — but as Cold War distrust grew between the two occupying powers, the line hardened into a lasting division, setting up the conditions for the Korean War in 1950.
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Defeated on the mainland, Jiang Jieshi and roughly two million Guomindang soldiers, officials and supporters fled across the Taiwan Strait in 1949. There, Jiang re-established his government as the Republic of China (ROC), still claiming to be the legitimate government of all China.
Establishing control
Jiang Jieshi's Guomindang took over an island that Japan had ruled as a colony until 1945, imposing mainland Chinese administrators and Mandarin over a population with its own Taiwanese identity and language.
Martial law (from 1949)
Jiang declared martial law, banning opposition parties, independent media and public dissent. It would remain in force for decades — one of the longest periods of martial law in modern history.
The White Terror
Thousands of real or suspected opponents of Guomindang rule — including many native Taiwanese — were arrested, imprisoned or executed in a sustained political crackdown.
Defeat on the mainland became one-party control on Taiwan: martial law + the White Terror.
228 Incident (February 1947) — the roots of it all: Even before the Guomindang's full retreat to Taiwan, tension between mainland officials and native Taiwanese had already exploded in the 228 Incident of February 1947, when a crackdown on protests killed thousands of Taiwanese. This crisis deepened distrust and fed directly into the harsh martial-law rule that followed.
Guomindang rule was not only repression, however. Jiang's government carried out land reform and used American aid to begin building Taiwan's economy — but political control stayed firmly one-party for decades.
- Beginnings of Taiwanese independence movement — resentment at mainland domination, memories of the 228 Incident, and the sense of a separate Taiwanese identity fed a movement (often organised by exiles abroad in this period) arguing Taiwan should determine its own future rather than be ruled as part of "China" by an exiled mainland government.
- Two Chinas problem begins — by 1950, there were two rival governments each claiming to be the true China: the communist People's Republic on the mainland, and the Nationalist Republic of China on Taiwan — a division that still shapes East Asian politics today.