Throughout the 1930s Japan had built up an empire in the Far East. It invaded Manchuria in North East China in 1931 and then moved deeper into the country in 1937. By July 1941, Japan had flooded French Indochina (now Vietnam) with troops. Japans aims were clear. The Japanese wanted to be the dominant power in Asia and remove the power and influence of the Europeans and the Americans from the region.
War with Japan officially broke out when the Japanese attacked the US fleet at Pearl Harbor on December 7th 1941. Within 7 hours Japanese forces attacked again, this time in Malaya, part of the British Empire, taking Empire forces totally by surprise. In a 9 week campaign Japanese forces fought their way through Malaya.
By early February they were ready to attack the vital British naval base at Singapore. Although the defenders outnumbered the Japanese attackers they had few aircraft and their troops were inexperienced. Singapore fell on February 15th 1942 and around 130 000 British, Australian and Indian troops became Japanese prisoners of war. Around 1 in 3 of the captives died.
From here the next focus of the fighting was Burma.
The Japanese were keen to try and cut the Burma Road. This was the supply line from India to China which Britain and the USA were using to supply Chinese forces who were still fighting the Japanese.
From January to May 1942 British Empire forces, mostly Indian troops, fought a harsh and costly campaign, gradually retreating to the borders of India in May 1942.
The year 1942 saw an effective stalemate. The British mounted a campaign at Arakan but it was unsuccessful and British commander General Slim was unable to force the Japanese out of Burma. Other campaigns in the war took priority in terms of troops and resources.
Early in 1943 Brigadier Orde Wingate led his Chindits (mostly Indian and Gurkha troops) in attacks behind enemy lines. The Chindits suffered heavy losses but they did show that British forces could match the Japanese in jungle warfare.
By late 1943 and early 1944 the tide of the war was beginning to turn. Slims forces began to get the troops and equipment they needed, especially aircraft. Early in 1944 there was a second Chindit expedition. However, the main clash of the year came in March-April as Japanese and mainly Indian forces fought for control of Kohima and Imphal. After much hard fighting the Japanese suffered decisive defeats, with around 55 000 casualties.
From this point on, the campaign became a steady drive to push the Japanese out of Burma. They fought ferociously, but by March 1945 the Allies recaptured Mandalay. They reached Rangoon in May 1945. Fighting continued in the area until July-August 1945. It was the longest single campaign fought by British Empire troops. Around 120 000 Africans, 2.5 million Indians and many thousands of British, Australian and New Zealand troops took part, as well as US forces.