The Second Sino-Japanese War was a military conflict fought primarily between the Republic of China and the Empire of Japan from July 7, 1937, to September 2, 1945. It began with the Marco Polo Bridge Incident in 1937 in which a dispute between Japanese and Chinese troops escalated into a battle. Some sources in the modern People's Republic of China date the beginning of the war to the Japanese invasion of Manchuria in 1931. It is known as the War of Resistance in China.