China Burma India Theater China Burma India Theater ( CBI ) was an umbrella term , used by the United States military during World War II for the China and Southeast Asian or India - Burma ( IBT ) theaters . Operational command of Allied forces ( including US forces ) in the CBI was officially the responsibility of the Supreme Commander s for South East Asia or China . However : US forces in practice were usually overseen by General Joseph Stilwell , the Deputy Allied Commander in China ; the term " CBI " was significant in logistical , materiel and personnel matters and ; it was and is commonly used within the US for these theaters . Well - known US ( or joint Allied ) units in the CBI included the Flying Tigers , transport and bomber units flying the Hump , the 1st Air Commando Group , the engineers who built Ledo Road , and the 5307th Composite Unit ( Provisional ) , popularly known as " Merrill ' s Marauders " . U . S . Strategy for China . In 1941 the U . S . made a series of decisions to support China in its war with Japan . Lend Lease funds began to flow because President Franklin D . Roosevelt announced the defense of China to be vital to the defense of the United States . Over the summer , as Japan moved south into French Indo - China , the U . S . , Britain and the Netherlands slapped an oil embargo on Japan , cutting off 90 % of its supplies . Japan did cut off overland supplies to China through Burma . China could be supplied only by flying over the Himalaya mountains ( " The Hump " ) from India , or capturing territory in Burma and building a new road — the Ledo Road . Burma . Japan was overextended . Its naval base could not defend its conquests , and its industrial base could not beef up the navy . To cut off China from Allied aid , it went into Burma , captured Rangoon on March 8 , 1942 , cutting the Burma Road lifeline to China . Moving north the Japanese took Tounggoo , Burma , then captured Lashio in upper Burma on April 29 . The British , primarily concerned with India , looked to Burma as the main theater of action against Japan and wanted Chinese troops to fight there . The United States conjured up visions of millions of Chinese soldiers who would hold the Japanese then throw them back , while providing close - in airbases for a systematic firebombing of Japanese cities . The overland supply route from India to China had to go through Burma . Chiang realized it was all fantasy . On the other hand there were vast sums of American dollars available if he collaborated . He did so and managed to feed his starving soldiers , but they were so poorly equipped and led that offensive operations against the Japanese in China were impossible . However , Chiang did release two Chinese armies for action in Burma under Stilwell . They were smashed by the Japanese and Stilwell , on foot , barely escaped to India ; the recovery of Burma and construction of the Ledo Road to supply China via Burma became an obsession for Stilwell . " On April 14 , 1942 , William Donovan , as Coordinator of Information ( forerunner of the Office of Strategic Services ) , activated Detachment 101 for action behind enemy lines in Burma . The first unit of its kind , the Detachment was charged with gathering intelligence , harassing the Japanese through guerrilla actions , identifying targets for the Army Air Force to bomb , and rescuing downed Allied airmen . Because Detachment 101 was never larger than a few hundred Americans , it relied on support from various tribal groups in Burma . In particular , the vigorously anti - Japanese Kachin people were vital to the unit ’ s success . " 101 ' s efforts opened the way for Stilwell ' s Chinese forces , Wingate ' s Raiders , Merrill ' s Marauders , and the counter - attack against the Japanese Imperial life - line . Allied Command structure . U . S . and Allied Land forces . US forces in the CBI were grouped together for administrative purposes under the command of General Joseph " Vinegar Joe " Stilwell . However , unlike other combat theaters , for example the European Theater of Operations , the CBI was never a " theater of operations " and did not have an overall operational command structure . Initially U . S . land units were split between those who came under the operational command of the India Command under General Sir Archibald Wavell , as the Commander - in - Chief in India , and those in China , which ( technically at least ) were commanded by Generalissimo Chiang Kai Shek , as the Supreme Allied Commander in China . However , Stilwell often broke the chain of command and communicated directly with the US Joint Chiefs of Staff on operational matters . This continued after the formation of the South East Asia Command ( SEAC ) and the appointment of Admiral Lord Mountbatten as Supreme Allied Commander . When joint allied command was agreed upon , it was decided that the senior position should be held by a member of the British military because the British dominated Allied operations on the South - East Asian Theatre by weight of numbers ( in much the same way as the US did in the Pacific Theater of Operations ) . Admiral Lord Mountbatten was appointed as the Supreme Allied Commander of South - East Asia forces in October 1943 . Gen . Stilwell , who also had operational command of the Northern Combat Area Command ( NCAC ) , a US - Chinese formation , was to report in theory to Gen . George Giffard — commander of Eleventh Army Group — so that NCAC and the British Fourteenth Army , under the command of General William Slim , could be co - ordinated . However , in practice , Gen . Stillwell never agreed to this arrangement . Stilwell was able to do this because of his multiple positions within complex command structures , including especially his simultaneous positions of Deputy Supreme Allied Commander South East Asia , and Chief of Staff to Chinese leader Generalissimo Chiang Kai - Shek . As SEAC ' s deputy leader , Stilwell was Giffard ' s superior , but as operational commander of NCAC , Giffard was Stilwell ' s superior . As the two men did not get on , this inevitably lead to conflict and confusion . Eventually at a SEAC meeting to sort out the chain of command for NCAC , Stilwell astonished everyone by saying " I am prepared to come under General Slim ' s operational control until I get to Kamaing " . Although far from ideal , this compromise was accepted . Although Gen . Stilwell was the control and co - ordinating point for all command activity in the theater , his assumption of personal direction of the advance of the Chinese Ledo forces into north Burma in late 1943 meant that he was often out of touch with both his own headquarters and with the over - all situation . Not until late 1944 , after Stilwell was recalled to Washington , was the chain of command clarified . His overall role , and the CBI command , was then split among three people : Lt Gen . Raymond Wheeler became Deputy Supreme Allied Commander South East Asia ; Major - General Albert Wedemeyer became Chief of Staff to Chiang , and commander of US Forces , China Theater ( USFCT ) . Lt Gen . Daniel Sultan was promoted , from deputy commander of CBI to commander of US Forces , India - Burma Theater ( USFIBT ) and commander of the NCAC . The 11th Army Group was redesignated Allied Land Forces South East Asia ( ALFSEA ) , and NCAC was decisively placed under this formation . However , by the time the last phase of the Burma Campaign began in earnest , NCAC had become irrelevant , and it was dissolved in early 1945 . U . S . Army and Allied Air Forces . After consultation among the Allied governments , Air Command South - East Asia was formed in November 1943 to control all Allied air forces in the theater , with Air Chief Marshal Sir Richard Peirse as Commander - in - Chief . Under Peirse ' s deputy , USAAF Major General George E . Stratemeyer , Eastern Air Command ( EAC ) was organized in 1943 to control Allied air operations in Burma , with headquarters in Calcutta . Unlike the strained relations and confusion encountered in coordinating Allied ground force commands , air force operations in the CBI proceeded relatively smoothly . Relations improved even further after new U . S . military aid began arriving , together with capable USAAF officers such as Brigadier General William D . Old of CGI Troop Carrier Command , and Colonels Philip Cochran and John R . Alison of the 1st Air Commando Group . Within Eastern Air Command , Air Marshal Sir John Baldwin commanded the Third Tactical Air Force , originally formed to provide close air support to the Fourteenth Army . Baldwin was later succeeded by Air Marshal Sir Alec Coryton . U . S . Brigadier - General Howard C . Davidson and later Air Commodore F . J . W . Mellersh commanded the Strategic Air Force . In the new command , various units of the Royal Air Force and the U . S . Tenth Army Air Force worked side - by - side . In the autumn of 1943 SEAAC had 48 RAF and 17 USAAF squadrons ; by the following May , the figures had risen to 64 and 28 , respectively . At Eastern Air Command , Gen . Stratemeyer had a status comparable to that of Stilwell . Coordinating the efforts of the various allied air components while maintaining relations with diverse command structures proved a daunting task . Part of Stratemeyer ' s command , the Tenth Air Force , had been integrated with the RAF Third Tactical Air Force in India in December 1943 and was tasked with a number of roles in support of a variety of allied forces . Another component , the USAAF Fourteenth Air Force in China , was actually under the jurisdiction of Generalissimo Chiang Kai - Shek as theater commander . Although the China - Buma - India operations of the USAAF ' s Air Transport Command received its assignments of tonnage from Stratemeyer as Stilwell ' s deputy , organizational control of the ATC remained in Washington , D . C . In the spring of 1944 , with the arrival of command B - 29 s in the theater , another factor would be added to air force operations . XX Bomber Command of the Twentieth Air Force was tasked with the strategic bombing of Japan under Operation Matterhorn , and reported directly to the JCS in Washington , D . C . However , XX Bomber Command remained totally dependent on Eastern Air Command for supplies , bases , ground staff , and infrastructure support . After a period of reshuffling , Eastern Air Command ' s air operations began to show results . In August 1944 , Admiral Mountbatten noted in a press conference that EAC fighter missions had practically swept the Japanese air force from Burmese skies . Between the formation of SEAAC in November 1943 , and the middle of August 1944 , American and British forces operating in Burma destroyed or damaged more than 700 Japanese aircraft with a further 100 aircraft probably destroyed . This achievement considerably reduced dangers to Air Transport Command cargo planes flying in support of the Hump airlift operation . By May 1944 , EAC resupply missions in support of the Allied ground offensive had carried 70 , 000 tons of supplies and transported a total of 93 , 000 men , including 25 , 500 casualties evacuated from the battle areas . These figures did not include tonnage flown in the Hump airlift missions to China . USAAF Order Of Battle . Tenth Air Force Transferred in 1944 to Fourteenth Air Force : Fourteenth Air Force Twentieth Air Force < BR > ( Attached To CBI 1944 – 1945 ) Twentieth Air Force XX Bomber Command ( XX BC ) combat elements moved in the summer of 1944 from the United States to India where they engaged in very - long - range Boeing B - 29 Superfortress bombardment operations against Japan , Formosa , China , Indochina and Burma . While in India , XX BC was supported logistically by Tenth Air Force and the India - China Division of the Air Transport Command . B - 29 groups moved to West Field , Tinian , in early 1945 .