South - East Asian theatre of World War II The South - East Asian Theatre of World War II was the name given to the campaigns of the Pacific War in Burma ( now Myanmar ) , Ceylon , India , Thailand , Indochina , Malaya and Singapore . Purposes of the conquest of these countries included the securing of natural resources such as rubber and petroleum from the European colonies in the region . Conflict in the theatre began when the Empire of Japan invaded Thailand and Malaya from bases located in Indochina on December 8 , 1941 . The main landing at Singora ( now Songkhla ) on the east side of the Isthmus of Kra preceded the bombing of Pearl Harbor by several hours . Action in the theatre officially ended on September 9 , 1945 . Initial Japanese successes . The Allies suffered many disastrous defeats in the first six months of the war . Two major British warships , HMS " Repulse " and HMS " Prince of Wales " were sunk by a Japanese air attack off Malaya on December 10 , 1941 . Following the invasion , the government of Thailand formally allied itself with Japan on December 21 . Japan invaded Hong Kong in the Battle of Hong Kong on December 8 , culminating in surrender on December 25 . January saw the invasions of Burma and the Dutch East Indies and the capture of Manila and Kuala Lumpur . The Japanese Southern Expeditionary Army Group ' s 1st Raiding Regiment ( also known as the 1st Parachute Brigade ) was used with good effect in the seizure of Sumatra ( see Battle of Palembang ) . Malaya and Singapore . Japanese forces met stiff resistance from III Corps of the Indian Army , the Australian 8th Division and British units during the Battle of Malaya , but Japan ' s superiority in air power , tanks and infantry tactics drove the Allied units back . After being driven out of Malaya , Allied forces in Singapore , under the command of Lieutenant General Arthur Percival , surrendered to the Japanese on February 15 , 1942 ; about 130 , 000 Allied troops became prisoners of war . The fall of Singapore was the largest surrender in British military history . The Japanese Indian Ocean raid . The Japanese Indian Ocean raid was a naval sortie by the Fast Carrier Strike Force of the Imperial Japanese Navy from March 31 to April 10 , 1942 against Allied shipping and bases in the Indian Ocean . Following the destruction of the ABDACOM forces in the battles around Java in February and March , the Japanese sortied into the Indian Ocean to destroy British seapower there and support the invasion of Burma . The raid was only partially successful . It did not succeed in destroying Allied naval power in the Indian Ocean but it did force the British fleet to relocate from British Ceylon to Kilindini near Mombasa in Kenya , as their more forward fleet anchorages could not be adequately protected from Japanese attack . The fleet in the Indian Ocean was then gradually reduced to little more than a convoy escort force as other commitments called for the more powerful ships . From May 1942 , it was also used in the invasion of Madagascar — an operation aimed at thwarting any attempt by Japan to use bases on the Vichy French controlled territory . In 1942 , Madras City was attacked by a Mitsubishi Rufe , ( the Zero ' s seaplane version ) operating from the carrier which dropped a single bomb near the St . George Fort . The physical damage was negligible , though the public response was major and the city was evacuated because of fears of subsequent Japanese bombing and invasion . Many rich families from Madras moved permanently to the hill stations in fear . Also in 1942 in preparation for a possible Japanese invasion of India , the British began improvements to the Kodaikanal - Munnar Road to facilitate its use as an evacuation route from Kodaikanal along the southern crest of the Palani Hills to Top Station . Existing roads then continued to Munnar and down to Cochin where British ships would be available for evacuation out of India . Japanese occupation of the Andaman and Nicobar Islands . The Andaman and Nicobar Islands ( 8 , 293 km² on 139 islands ) , are a group of islands situated in the Bay of Bengal at about 780 miles from Kolkata ( known at the time as Calcutta ) , 740 miles from Chennai ( known at the time as Madras ) and 120 miles from Cape Nargis in Burma . On March 23 , 1942 a Japanese invasion force seized the islands and occupied them until the end of the war . On December 29 , 1943 , political control of the islands was theoretically passed to the Azad Hind government of Subhas Chandra Bose . Bose visited Port Blair to raise the tricolour flag of the Indian National Army . After Bose ' s departure the Japanese remained in effective control of the Andamans , and the sovereignty of the " Arzi Hukumat - e Hind " was largely fictional . The islands themselves were renamed " Shaheed " and " Swaraj " , meaning " martyr " and " self - rule " respectively . Bose placed the islands under the governorship of Lt Col . A . D . Loganathan , and had limited involvement with the administration of the territory . Burma Campaign . US forces in the China Burma India Theatre . One of the major logistical efforts of the war was " flying the Hump " over the Himalayas and the building of the Ledo Road from India to China as a replacement for the Burma Road . Air war in South East Asia . RAF battle honours : Qualification : For operations against Japanese aircraft and naval units by squadrons based in Ceylon during the Japanese attacks of April 1942 . Qualification : For operations during the 14th Army ' s advance from Imphal to Rangoon , the coastal amphibious assaults , and the Battle of Pegu Yomas , August 1944 to August 1945 . Indian Ocean naval campaigns 1942 – 45 . The earliest successes were gained by mine laying and submarine warfare . The Japanese minesweeping capability was never great , and when confronted with new types of mines they did not adapt quickly . Japanese shipping was driven from the Burmese coast using this type of warfare . British submarines based in British Ceylon operated against Japanese shipping . It was only after the war in Europe was clearly coming to an end that large British forces were dispatched to the Indian Ocean again . Following the neutralisation of the German fleet in late 1943 and early 1944 , forces from the Home Fleet were released , and the success of Operation Overlord in June meant even more craft could be sent , including precious amphibious assault shipping . During late 1944 , as more British aircraft carriers came into the area a series of strikes were flown against oil targets in Sumatra , such as Operation Meridian . The USS " Saratoga " was lent for the first attack by the United States . The oil installations were heavily damaged by the attacks , aggravating the Japanese fuel shortages due to the American blockade . The final attack was flown as the carriers were heading for Sydney to become the British Pacific Fleet . After the departure of the main battle forces the Indian Ocean was left with escort carriers and older battleships as the mainstay of its naval forces . Nevertheless , during those months important operations were launched in the recapture of Burma , including landings on Ramree and Akyab and near Rangoon . Command structures . Allied command structure . At the start of the war the British had two commands with responsibilities for possessions in the theatre . India Command under General Sir Archibald Wavell the Commander - in - Chief ( CinC ) of the Army of India and the Far East Command , first under Air Chief Marshal Robert Brooke - Popham and then from December 23 , 1941 commanded by Lieutenant - General Sir Henry Royds Pownall . India Command was responsible for British India , British Ceylon , and for some of the time Burma . The Far East Command based in Singapore was responsible for Hong Kong , Malaya , Singapore and other British Far East possessions including , for some of the time , Burma . A month after the outbreak of war with Japan on December 7 , 1941 , the Allied governments jointly appointed the British Commander - in - Chief ( CinC ) of the Army of India , General Sir Archibald Wavell , as Supreme Allied Commander of all " American - British - Dutch - Australian " ( ABDA ) forces in South East Asia and the Pacific , from Burma to the Dutch East Indies . However , advances made by the Japanese over the next month split the ABDA forces in two . After transferring the forces in Burma to the India Command , on February 25 , 1942 Wavell resigned as commander of the ABDA and resumed his position of CinC of the Army of India . Responsibility for the South West Pacific Area passed to US General Douglas MacArthur as " Supreme Allied Commander South West Pacific " . From February 1942 until November 1943 the India Command was responsible for the South East Asian Theatre . General Wavell was made Viceroy of India and General Claude Auchinleck became Commander - in - Chief of the India Command on the 20th June , 1943 . In August 1943 the Allies formed a new South East Asian Command to take over strategic responsibilities for the theatre . The reorganisation of the theatre command took about two months . On October 4 Winston Churchill appointed Admiral Lord Louis Mountbatten supreme Allied commander of the South East Asia Command ( SEAC ) . The American General Joseph Stilwell was the first deputy supreme Allied commander . On November 15 , Auchinleck handed over responsibility for the conduct of operations against the Japanese in the theatre to Mountbatten . The initial land forces operational area for SEAC included India , Burma , British Ceylon and Malaya . Operations were also mounted in Japanese - occupied Sumatra , Thailand and French Indochina ( Viet Nam , Cambodia , and Laos ) . Initially SEAC commanded : In October 1944 , CBI was split into US Forces China Theater ( USFCT ) and India - Burma Theater ( USFIBT ) . On November 12 , 1944 Eleventh Army Group redesignated by Allied Land Forces South East Asia ( ALFSEA ) combining Commonwealth and US forces , with an HQ at Kandy . On December 1 ALFSEA HQ moved to Barrackpore , India . On August 15 , 1945 responsibility for the rest of the Dutch East Indies was transferred from the South West Pacific Area to SEAC . SEAC was disbanded on November 30 , 1946 . 11th Army Group . British 11th Army Group ( November 1943 – November 12 , 1944 ) was on paper the main Commonwealth army force in South East Asia which directed On November 12 , 1944 the 11th Army Group was redesignated Allied Land Forces South East Asia , still under SEAC , because it was felt that an inter - Allied command was better than the purely British headquarters . Command problems with General Stilwell and his interactions with the U . S . Joint Chiefs of Staff had precipitated the change . Japanese command structure . The Imperial Japanese Army Unit controlling all army land and air units in South East Asia and the South West Pacific was the Southern Expeditionary Army headquartered in Saigon , Indochina . It was commanded by General Count Hisaichi Terauchi , who commanded it from 1941 to 1945 . The Japanese also deployed the South Seas Force , a combined force of Army and Special Naval Landing Force personnel . The Southern Army ' s major field commands were the Japanese 14th Army , the Japanese 15th Army , the Japanese 16th Army and the Japanese 25th Army . These consisted of 11 infantry divisions , six independent infantry brigades , and six tank regiments , plus artillery and support troops . The Japanese extensively used bicycle infantry , which allowed them quick movement over vast distances .