South East Asia Command (SEAC) was the body set up to be in overall charge of Allied operations in the South-East Asian Theatre during the Second World War.

In August 1943, with the agreement of the Combined Chiefs of Staff, Winston Churchill appointed Admiral Lord Louis Mountbatten as Supreme Allied Commander South East Asia.

UK participants were focused on Nazi Germany, and saw the war against Japan being limited "to the defense of a fixed line in front of those positions that must be held".

[5] However, because such an approach was unacceptable to the United States, it was agreed that there would be offensive actions in Burma, operations in support of China, and other activity beyond holding a defensive line in South East Asia, as a result of US demands that the Japanese be kept off-balance, throughout any areas in which they might encounter Allied forces.

[8] On 2 December 1943, the Combined Chiefs of Staff officially approved in principle a plan designating the Pacific Ocean Areas as the focus of the main effort against Japan.

A secondary line of advance – by US and Australian forces – "along the New Guinea-N.E.I.-Philippine axis", was to be controlled by the separate South West Pacific Area command under Douglas MacArthur (US Army).

The 11th Army Group was redesignated Allied Land Forces South East Asia (ALFSEA) under a new commander Lieutenant-General Oliver Leese who had relinquished command of the Eighth Army in Italy, and NCAC (which by this time included Chinese, American and British units) was placed under ALFSEA.

[11] As the drive to liberate Burma began in earnest however, Chiang Kai-shek and Wedemeyer made increasing demands for NCAC's formations to be moved to the China Theatre to meet the threat of Japanese attacks from the north.

[12] RAF aircraft destined for SEAC had the word "SNAKE" applied after the serial during ferrying to prevent them being appropriated by other commands along the route.

French Indochina was added, along with Borneo – most of which had already been captured by Australian forces, under the South West Pacific Command – and Java.

At the same time, Western governments expected SEAC to re-establish colonial regimes in territories lost to Japan in 1941–45 where nationalist, anti-colonial forces had gained strength.

After Japan's surrender, Lt. General Itagaki Seishiro, who commanded the Japanese Seventh Area Army in Southeast Asia, were sent to Tokyo to stand trial for war crime.

A wave of strikes swept Singapore, led by Communist leaning labour unions and hundreds of thousands their members.

[15] British Commonwealth troops were landed in the Dutch East Indies (Indonesia) and French Indochina to facilitate the return of forces from the pre-war colonial powers.

Sarawak and Sumatra did not prove to be major headaches for the British, except that one Japanese unit in Borneo refused to surrender until November 1945.

It was intended that British forces would temporarily enforce military government over a small section of Indochina, because of local resistance, logistics and French sensibilities.

Aided by armed militias formed by the Japanese during the occupation, Indonesian nationalists in Java declared the Dutch East Indies a republic, and independent from the Netherlands.