The Second Sino-Japanese War (1937–1945) or War of Resistance (Chinese term) was a military conflict that was primarily waged between the Republic of China and the Empire of Japan. The war made up the Chinese theater of the wider Pacific Theater of the Second World War. The beginning of the war is conventionally dated to the Marco Polo Bridge Incident on 7 July 1937, when a dispute between Japanese and Chinese troops in Peking escalated into a full-scale invasion. Some Chinese historians believe that the Japanese invasion of Manchuria on 18 September 1931 marks the start of the war. This full-scale war between the Chinese and the Empire of Japan is often regarded as the beginning of World War II in Asia.