During the early stages of World War II, the Empire of Japan invaded British Burma primarily to obtain raw materials (which included oil from fields around Yenangyaung, minerals and large surpluses of rice), and to close off the Burma Road, which was a primary link for aid and munitions to the Chinese Nationalist forces of Chiang Kai-shek which had been fighting the Japanese for several years in the Second Sino-Japanese War.

The BIA formed a provisional government in some areas of the country in the spring of 1942, but there were differences within the Japanese leadership over the future of Burma.

Though now nominally independent, the power of the State of Burma to exercise its sovereignty was largely circumscribed by wartime agreements with Japan.

The Imperial Japanese Army maintained a large presence and continued to act arbitrarily, despite Japan no longer having official control over Burma.

Aung San and others subsequently began negotiations with Lord Mountbatten and officially joined the Allies as the Patriotic Burmese Forces.

Without the support of the BNA, the government of the State of Burma quickly collapsed, and Ba Maw fled via Thailand to Japan, where he was captured later that year and was held in Sugamo Prison, Tokyo, until 1946.