The Second Sino-Japanese War (July 7, 1937 ? September 9, 1945) was a military conflict fought between the Republic of China and the Empire of Japan. From 1937 to 1941, China fought Japan with some economic help from Germany (until 1938) and the Soviet Union (1937-1940). After the Japanese attack on Pearl Harbor, the war merged into the greater conflict of World War II as a major front in the Pacific Theatre. The Second Sino-Japanese War was the largest Asian war in the twentieth century.

Although the two countries had fought intermittently since 1931, full-scale war started in earnest in 1937 and ended only with the surrender of Japan in 1945. The war was the result of a decades-long Japanese imperialist policy aiming to dominate China politically and militarily, and to secure its vast raw material reserves and other economic resources, particularly food and labor. At the same time, the rising tide of Chinese nationalism and notions of self determination stoked the coals of war. Before 1937, China and Japan fought in small, localized engagements in so-called "incidents". Yet the two sides, for a variety of reasons, refrained from fighting a total war. In 1931, the Japanese invasion of Manchuria by Imperial Japan's Kwantung Army followed the "Mukden Incident". The last of these incidents was the Marco Polo Bridge Incident of 1937, marking the beginning of full scale war between the two countries.

?