MAP I: It is sometimes forgotten that Japan had already been at war with China for 10 years before the attack on Pearl Harbor in 1941. Having established a ‘protectorate’ over Korea in 1910, the Japanese Army with the backing of Emperor Hirohito used the fabricated 18 September 1931 Mukden Incident (the blowing up of a section of railway) as an excuse to annexe Manchuria and expand Japan’s ‘co-prosperity sphere’. However a full scale war against China did not develop until 1937; arguably World War II started in Asia in this year rather than the normally stated 1939.