The Japanese invasion of Burma was the opening phase of the Burma campaign in the South-East Asian theatre of World War II, which took place over four years from 1942 to 1945. During the first year of the campaign (December 1941 to mid-1942), the Japanese Army (with aid from Thai Phayap Army and Burmese insurgents) drove British Empire and Chinese forces out of Burma, then began the Japanese occupation of Burma and formed a nominally independent Burmese administrative government.