March 1944 - May 1944
In March-April 1944 three Japanese divisions and one division of the Indian National Army under Subhas Chandra Bose had been decisively beaten at Imphal and Kohima by British and Indian forces. 60,000 Japanese had died.
In May 1944 three Chinese armies together with American Special Forces ("Merrill's Marauders") attacked Myitkyina. The town and airstrip were taken only after a three month siege and a ferocious resistance by the Japanese 33rd Army.
Over the same months, the Allies landed more than 20,000 Indian, Gurkha, and British Special Forces (the "Chindits", from Burmese "Chinthe"), behind Japanese lines in northern Burma - in what was the biggest Allied airborne operation in history. The Americans led air operations, which included the first helicopters ever used in war.
The Allied objective was to reopen land and air routes between India and China. The reconquest of Burma was a British objective but not a high priority. By late 1944 over one million Allied troops and 300,000 Japanese troops were involved in the battles for Burma.
(This video is from a news clip made 75 years ago in the UK about the fighting in Burma)