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 and has been described as "the Asian Holocaust", in reference to the scale of Japanese war crimes against Chinese civilians. It is known in China as the War of Resistance against Japanese Aggression (simplified Chinese: 抗日战争; traditional Chinese: 抗日戰爭).
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. Chinese Nationalist and Communist 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 full-scale war began on 7 July 1937 with the Marco Polo Bridge incident near Beijing, which prompted a full-scale Japanese invasion of the rest of China. The Japanese captured the capital of Nanjing in 1937 and perpetrated the Nanjing Massacre. After failing to stop the Japanese capture of Wuhan in 1938, then China's de facto capital at the time, the Nationalist government relocated to Chongqing in the Chinese interior. After the Sino-Soviet Non-Aggression Pact, Soviet aid bolstered the National Revolutionary Army and Air Force. By 1939, after Chinese victories at Changsha and with Japan's lines of communications stretched deep into the interior, the war reached a stalemate. The Japanese were unable to defeat Chinese Communist Party forces in Shaanxi, who waged a campaign of sabotage and guerrilla warfare. In November 1939, Chinese nationalist forces launched a large scale winter offensive, and in August 1940, communist forces launched the Hundred Regiments Offensive in central China.
In December 1941, Japan launched a surprise attack on Pearl Harbor and declared war on the United States. The US increased its aid to China under the Lend-Lease Act, becoming its main financial and military supporter. With Burma cut off, the United States Army Air Forces airlifted material over the Himalayas. In 1944, Japan launched Operation Ichi-Go, the invasion of Henan and Changsha. In 1945, the Chinese Expeditionary Force resumed its advance in Burma and completed the Ledo Road linking India to China. China launched large counteroffensives in South China and repulsed a failed Japanese invasion of West Hunan and recaptured Japanese occupied regions of Guangxi.
Japan formally surrendered on 2 September 1945, following the atomic bombings of Hiroshima and Nagasaki, Soviet declaration of war and subsequent invasions of Manchukuo and Korea. The war resulted in the deaths of around 20 million people, mostly Chinese civilians. China was recognized as one of the Big Four Allies, regained all territories lost, and became one of the five permanent members of the United Nations Security Council. The Chinese Civil War resumed in 1946, ending with a communist victory and the Proclamation of the People's Republic of China in 1949.
Work in progress...