Sino-Japanese Chronology

Origins
Following the Manchurian Incident  (Sept., 1931), the Japanese Kwantung army occupied Manchuria and established the puppet state of Manchukuo  (Feb., 1932). Japan pressed China to recognize the independence of Manchukuo, suppress anti-Japanese activities, and form autonomous regional governments in N China. The Japanese were partially successful in 1933 and 1935 when they forced China to form two demilitarized autonomous zones bordering Manchuria.

Outbreak of War
Growing domestic opposition to the Nationalist government's policy of self-strengthening before counterattacking in N China and Manchuria led to the kidnapping of Chiang Kai-shek was kidnapped at Xi'an in Dec., 1936, by Chang Hsüeh-liang . Chiang was forced to agree to a united anti-Japanese front with the Communists as a condition for his release. The situation was tense, and in 1937 full war commenced. A clash (July, 1937) between soldiers of the Japanese garrison at Beijing and Chinese forces at the Marco Polo Bridge was the pretext for Japanese occupation at Beijing and Tianjin. Chiang Kai-shek refused to negotiate an end to hostilities on Japanese terms and placed crack troops outside the Japanese settlement at Shanghai. After a protracted struggle Shanghai and the national capital, Nanjing, fell to the Japanese. The Chinese broke the Huang He  dikes (June, 1938) to slow the enemy advance. In late 1938, Hankou and Guangzhou were taken.Japanese strategy was aimed at taking the cities, the roads, and the railroads, thereby gaining a net of control. Thus, although the Japanese by 1940 had swept over the eastern coastal area, guerrilla fighting still went on in the conquered regions. The Nationalist government, driven back to a temporary capital at Chongqing, struggled on with little help from outside. Chinese resources were inadequate, and the supplies sent over the Burma Road were far from sufficient. The Chinese cause continued to decline despite vast resistance and bloody fighting. Dubious of China's ability to sustain a protracted war, Wang Ching-wei  broke with Chiang Kai-shek and established a collaborationist regime at Nanjing (1940).

World War II
The Japanese bombing of Pearl Harbor brought the United States into the war and merged the Sino-Japanese War into World War II  as China declared war on Japan, Germany, and Italy. American and British loans and supplies, the establishment of military air bases in China, and the aid of an increasing number of U.S. and British advisers helped relieve China as Japan diverted armies elsewhere. Nevertheless, China's military position continued to deteriorate until Apr., 1945. In May the Chinese launched a successful offensive at Zhijiang (Chihkiang) that lasted until Japanese capitulation on Aug. 14. The Japanese troops in China formally surrendered Sept. 9, 1945. By the provisions of the Cairo Declaration, Manchuria, Taiwan, and the Pescadores were restored to China.

Adapted from:  http://www.encyclopedia.com/searchpool.asp?target=@DOCTITLE%20Sino-
Japanese%20War%20%20Second