Second Sino-Japanese War

The Second Sino-Japanese War was the war between the Empire of Japan and the Republic of China that began in July 1937 and ended with Japan's surrender in 1945. It is called “second” because Japan and Qing China had fought the First Sino-Japanese War in 1894–1895. In China it is known as the War of Resistance against Japan (Kangri zhanzheng); in Japan it was officially called the “China Incident” during the war and is now usually called the Japan–China War (Nitchū sensō).

It was the largest war in Asian history. For more than four years, from 1937 to December 1941, China fought Japan largely alone. After Japan attacked Pearl Harbor and British and Dutch colonies in December 1941, the war became part of the Second World War, with China fighting alongside the United States, Britain and the Soviet Union.

For China the war was a catastrophe: millions were killed, cities were bombed, and tens of millions became refugees. It also transformed Chinese politics, helping the Communist Party grow into the force that won the civil war in 1949. For Korea, then a Japanese colony, the war meant harsh mobilisation at home and an armed independence struggle abroad.

Since the late nineteenth century Japan had become an industrial and imperial power. It took Taiwan from China in 1895, gained rights in southern Manchuria after the Russo-Japanese War of 1904–1905, and annexed Korea in 1910. In 1915 it pressed the Twenty-One Demands on China to expand its influence. Many Japanese leaders saw China, and especially resource-rich Manchuria, as essential for Japan's security and economy.

China, meanwhile, was divided. After the fall of the Qing dynasty in 1912, warlords fought for power until Chiang Kai-shek's Nationalist Party (Guomindang) unified much of the country in 1928. The Nationalists then fought a bitter civil war against the Chinese Communist Party. On 18 September 1931 officers of Japan's Kwantung Army staged a bomb explosion on a railway near Shenyang (Mukden) and used it as an excuse to occupy all of Manchuria, where Japan set up the puppet state of Manchukuo in 1932, with the former Qing emperor Puyi as its head. When the League of Nations criticised this, Japan left the League in 1933.

Japanese pressure on northern China grew in the following years. In December 1936 Chiang was detained by two of his own generals in the Xi'an Incident and pushed to stop fighting the Communists and form a united front against Japan. By 1937, Chinese public opinion demanded resistance, while in Japan the army had great political power and many leaders believed China could be defeated quickly.

Japan fought with a well-trained, well-equipped army, a powerful navy and air force. It also created and used collaborationist governments in occupied China: Manchukuo in the north-east and, from 1940, the Reorganised National Government in Nanjing under Wang Jingwei, a former Nationalist leader. Soldiers and labourers from Japan's colonies, Korea and Taiwan, were increasingly mobilised for its war effort.

On the Chinese side, the Nationalist government under Chiang Kai-shek led the main armies and fought most of the large conventional battles. The Chinese Communist Party, with its Eighth Route Army and New Fourth Army, fought mainly guerrilla warfare behind Japanese lines in northern and central China and built base areas there. The united front between the two parties was always tense and broke down in open clashes, such as the New Fourth Army Incident of January 1941.

Foreign help mattered. The Soviet Union supplied aircraft, advisers and loans from 1937 until 1941. The United States gave loans, then Lend-Lease aid, and volunteer pilots known as the Flying Tigers; after 1941 supplies flew over the Himalayas (“the Hump”) or went by the Burma Road. Exiles from Korea and other lands also fought on China's side, including the Korean Liberation Army and the Korean Volunteer Corps.

On the night of 7 July 1937, Japanese and Chinese troops exchanged fire near the Marco Polo Bridge (Lugouqiao) south-west of Beijing. Neither side backed down, and within weeks Japan had occupied Beijing and Tianjin. In August fighting spread to Shanghai, where Chiang committed his best German-trained divisions. The Battle of Shanghai lasted about three months and cost enormous casualties on both sides before the Chinese retreated in November.

Japanese forces then advanced on the Nationalist capital, Nanjing, which fell on 13 December 1937. What followed, the Nanjing Massacre, is described in the next section. The Chinese government moved first to Wuhan and later to Chongqing in Sichuan, far up the Yangtze River, which became the wartime capital.

In spring 1938 Chinese forces won a notable victory at Taierzhuang in Shandong, showing that the Japanese army could be beaten. But Japan continued to advance. In June 1938, to slow the Japanese, Nationalist forces broke the dikes of the Yellow River near Huayuankou; the flood killed hundreds of thousands of Chinese civilians and made millions homeless. Wuhan and Guangzhou fell in October 1938. By then Japan controlled most of China's coast, major cities and railways, but China had not surrendered.

After capturing Nanjing on 13 December 1937, Japanese troops carried out mass killings of Chinese prisoners of war and civilians, widespread rape, looting and arson over a period of about six weeks, with atrocities in the surrounding countryside beginning earlier and continuing into early 1938. Large groups of disarmed soldiers and men suspected of being soldiers were executed by shooting, bayoneting and other means, often along the Yangtze River. Women and girls of all ages were raped, many then killed; the most commonly cited estimate is about 20,000 rapes, though estimates range much higher and lower.

A small group of Westerners who stayed in the city, including the German businessman John Rabe, the American missionary Minnie Vautrin and others, organised the Nanking Safety Zone, where around 200,000 or more Chinese sought refuge. Their diaries, letters and reports, along with the film of the missionary John Magee and reports by foreign journalists, are among the most important contemporary evidence. Diaries of Japanese soldiers and Chinese survivors' testimonies add further evidence.

The number of victims is the subject of intense debate. The International Military Tribunal for the Far East (the Tokyo Trial) concluded that more than 200,000 people were killed. The Nanjing War Crimes Tribunal of 1947 gave a figure of more than 300,000, which is the official figure in the People's Republic of China. Many Japanese and Western historians give estimates ranging from tens of thousands to around 200,000, depending on how they define the area, the time period and the victims (for example, whether executed prisoners of war are counted). A small number of Japanese writers deny that a massacre took place at all, a position rejected by mainstream historians. General Matsui Iwane was executed after the Tokyo Trial, and General Tani Hisao after the Nanjing tribunal; Prince Asaka Yasuhiko, a member of the imperial family who commanded troops at Nanjing, was never prosecuted.

From 1939 the war settled into a long stalemate. Japan held the cities and railways of the east but could not conquer the vast interior. It bombed Chongqing repeatedly from 1938 to 1943, killing many civilians. Chinese forces defended Changsha in several battles. In 1940 the Communist Eighth Route Army launched the Hundred Regiments Offensive against Japanese railways and posts in northern China. Japan responded with brutal “mopping-up” operations in Communist base areas, known in Chinese as the “Three Alls” policy (kill all, burn all, loot all), which devastated villages.

After Japan attacked Pearl Harbor on 7 December 1941, China formally declared war on Japan and became one of the Allies. In 1943 Britain and the United States gave up their extraterritorial rights in China, and at the Cairo Conference that year Chiang met Roosevelt and Churchill; the Cairo Declaration promised that territories taken from China, such as Manchuria and Taiwan, would be restored, and that Korea would become free and independent “in due course”. Chinese troops also fought in Burma alongside British and American forces.

In 1944 Japan launched Operation Ichi-Go, its largest offensive of the war, to secure a land corridor through China and destroy American air bases. It inflicted heavy defeats on Nationalist armies and weakened Chiang's government. The end came from outside: the United States dropped atomic bombs on Hiroshima (6 August 1945) and Nagasaki (9 August), and the Soviet Union invaded Manchuria on 9 August. Emperor Hirohito announced Japan's surrender on 15 August; the formal surrender was signed on 2 September in Tokyo Bay, and Japanese forces in China surrendered in Nanjing on 9 September 1945.

Casualty figures are uncertain and politically sensitive. Estimates of total Chinese deaths, military and civilian, from 1937 to 1945 commonly range from about 14 million to 20 million or more; the Chinese government has given a figure of 35 million casualties (killed and wounded) for 1931–1945. Nationalist army records list over 1.3 million soldiers killed, and Communist forces reported several hundred thousand more. Japanese military deaths in China are estimated at roughly 450,000 to 700,000. Many deaths came not from combat but from famine, disease and displacement.

The war created one of the largest refugee crises in history; estimates of the number of Chinese who fled their homes often reach 80 to 100 million. The deliberate breaching of the Yellow River dikes in 1938 caused a flood whose death toll is estimated at roughly 400,000 to 900,000. The Henan famine of 1942–1943, worsened by war, requisitioning and government failure, killed perhaps one to three million people.

Japanese forces committed many war crimes beyond Nanjing. Unit 731 near Harbin conducted lethal human experiments and developed biological weapons, which were used against Chinese cities and villages; Japan also used chemical weapons. The Japanese military set up a system of “comfort stations” in which women and girls from Korea, China, Taiwan, the Philippines, Indonesia and elsewhere were forced into sexual slavery; Korean women were among the largest groups, though exact numbers are unknown and estimates vary from tens of thousands to much higher. Millions of Chinese were also forced into labour, both in China and in Japan.

Korea had been a Japanese colony since 1910, and the war in China changed life there sharply. Japan turned Korea into a base for its war and pursued “imperialisation” (kōminka) policies meant to turn Koreans into loyal imperial subjects: Koreans were made to recite the Pledge of Imperial Subjects and worship at Shinto shrines, Korean-language education was cut back, and from 1940 families were pressed to adopt Japanese-style names. The National General Mobilisation Law of 1938 was applied to Korea, and from 1939 hundreds of thousands of Koreans were mobilised, often by coercion, to work in mines, factories and construction sites in Japan, Korea and elsewhere. Japan introduced a “volunteer” soldier system in 1938 and conscription in 1944. Many Korean women became victims of the military comfort-women system.

At the same time, the Korean independence movement fought on in China. The Provisional Government of the Republic of Korea, founded in Shanghai in 1919, had to leave the city after Yun Bong-gil's bombing attack on Japanese leaders in Hongkou Park in April 1932. It moved from city to city as the Japanese advanced and settled in Chongqing in 1940. On 17 September 1940 it founded the Korean Liberation Army, led by Ji Cheong-cheon as commander, with support from the Chinese Nationalist government. The Provisional Government declared war on Japan in December 1941.

Another force, the Korean Volunteer Corps, was formed in Hankou (Wuhan) in October 1938 under Kim Won-bong. Many of its members later moved to Communist-held areas of northern China, where they formed the Korean Volunteer Army, while the rest joined the Korean Liberation Army in 1942. Korean Liberation Army units worked with the British on the India–Burma front and in 1945 trained with the American Office of Strategic Services (OSS) for a planned operation to infiltrate Korea, which was overtaken by Japan's sudden surrender. After liberation the United States military government did not recognise the Provisional Government, and its leaders returned to Korea as individuals. In South Korea the Provisional Government and the Liberation Army are honoured as the roots of the Republic, and the Constitution refers to the legacy of the Provisional Government.

Japan's defeat ended its empire. Taiwan was returned to China, Korea was liberated but divided into Soviet and American occupation zones at the 38th parallel, and Japan itself was occupied by the Allies. The Tokyo Trial (1946–1948) and trials in China and elsewhere prosecuted Japanese leaders and soldiers for war crimes, although some key figures, including members of the imperial family and the leaders of Unit 731, were not tried.

In China, the war exhausted the Nationalist government through military losses, inflation and corruption, while the Communist Party expanded its army and territory behind Japanese lines. Civil war resumed in 1946, and in 1949 the Communists founded the People's Republic of China; the Nationalists retreated to Taiwan. Many historians see the war with Japan as the decisive factor in this outcome.

China's role in the war also raised its international status: the Republic of China became one of the five permanent members of the new United Nations Security Council. Relations between Japan and the People's Republic were normalised only in 1972. Questions of apology, compensation, textbooks and commemoration have remained sources of tension between China, Korea and Japan ever since.

In the People's Republic of China, the War of Resistance is central to national memory and patriotic education. For decades the Communist Party emphasised its own guerrilla role and downplayed the Nationalists; since the 1980s, the contribution of Nationalist armies has been more openly acknowledged. The Nanjing Massacre Memorial Hall opened in 1985, and in 2014 China established 3 September as Victory Day and 13 December as a national memorial day for the Nanjing Massacre victims. In 2017 Chinese textbooks were directed to describe a “fourteen-year war” beginning in 1931. In Taiwan, the Nationalist tradition long presented Chiang's leadership as the core of the resistance, while many Taiwanese families experienced the war as subjects of Japan.

In Japan, memory is divided. Many Japanese remember the war mainly through their own suffering, such as air raids and the atomic bombings. Official statements, notably Prime Minister Murayama Tomiichi's 1995 statement, have expressed “deep remorse” and apology for colonial rule and aggression. At the same time, visits by politicians to Yasukuni Shrine, where convicted Class-A war criminals are among those enshrined, and school textbook controversies, such as the historian Ienaga Saburō's long lawsuits against government textbook screening, show continuing disputes. Some nationalist groups minimise or deny the Nanjing Massacre and the coercion of comfort women, while many Japanese historians and citizens have documented these crimes.

In Korea, the war is remembered as part of the colonial period and the struggle for liberation, celebrated on 15 August (Gwangbokjeol). The suffering of forced labourers and comfort women remains a major issue in relations with Japan, including a 2015 bilateral agreement on comfort women that was contested in Korea and court rulings from 2018 on forced labour compensation. In the West, the China theatre was long a “forgotten” part of the Second World War; Iris Chang's 1997 book The Rape of Nanking and later scholarship brought it wider attention.

Sources for the war are vast but uneven. Japanese military and government records survive in large numbers, but many were deliberately burned in the days between Japan's decision to surrender and the arrival of Allied forces in August 1945, which complicates research on atrocities and the comfort-women system. Nationalist government archives are held mainly in Taipei (Academia Historica) and Nanjing (the Second Historical Archives of China); Chiang Kai-shek's diaries, opened to researchers at the Hoover Institution in the 2000s, give insight into his decisions. Communist Party records are less accessible.

For the Nanjing Massacre, the most important contemporary sources include John Rabe's diary, Minnie Vautrin's diary, the records of the Safety Zone committee, reports by the journalists Tillman Durdin and Archibald Steele, John Magee's film, burial records of charitable organisations such as the Red Swastika Society, diaries and later testimonies of Japanese soldiers, and survivors' testimonies collected after the war. The records of the Tokyo Trial and the Nanjing tribunal contain much evidence but were produced in a legal context.

For Korea, sources include the records and publications of the Provisional Government, documents of the Korean Liberation Army and OSS files, Japanese colonial government statistics on mobilisation, and oral histories of forced labourers and comfort-women survivors, many of whom began to speak publicly only in the 1990s, starting with Kim Hak-sun's testimony in 1991.

The death toll at Nanjing has become the most politically charged numerical question of the war. Japanese historiography is often described as divided into a “great massacre” school (historians such as Hora Tomio, Fujiwara Akira and Kasahara Tokushi, who accept figures in the range of over 100,000 to about 200,000 or more), a “middle” school (such as Hata Ikuhiko, who estimated about 40,000), and an “illusion” or denial school. Chinese scholars generally support the figure of 300,000. The Japan–China Joint History Research project, whose reports appeared in 2010, recorded Japanese scholars' estimates ranging from 20,000 to 200,000 and the Chinese side's figure of over 300,000. Differences arise from the geographical and chronological limits used, the treatment of executed prisoners of war, the reliability of burial records and testimony, and the pre-war population of the city. Historians broadly agree, however, that large-scale atrocities took place; Joshua Fogel's edited volume (2000) and Takashi Yoshida's work examine how the massacre was remembered and argued over in China, Japan and the United States.

A second debate concerns who fought the war. Rana Mitter's Forgotten Ally (2013) and the work of Hans van de Ven and others argue that the Nationalists bore the brunt of conventional fighting and that China's long resistance tied down large Japanese forces, a contribution long underestimated in the West and, for decades, in the People's Republic. The periodisation is also debated: the official Chinese “fourteen-year war” (1931–1945) emphasises continuity from the Manchurian Incident, while many international historians still date the full-scale war from 1937.

Historians of Korea examine the war's impact on colonial society, including the scale and nature of forced mobilisation, the question of collaboration and resistance, and the international recognition of the Provisional Government. Debates over the coercion of comfort women and forced labourers continue in academic and political arenas, with survivor testimony, Japanese military documents found by historians such as Yoshimi Yoshiaki, and the 1993 Kōno Statement, in which the Japanese government acknowledged military involvement, central to the discussion.