The fighting in the Burma campaign in 1944 was among the most severe in the South-East Asian Theatre of World War II. It took place along the borders between Burma and India, and Burma and China, and involved the British Commonwealth, Chinese and United States forces, against the forces of Imperial Japan and the Indian National Army. British Commonwealth land forces were drawn primarily from the United Kingdom, British India and Africa.

The Allies had overcome the logistic and organisational difficulties which had crippled their earlier efforts, and they were preparing to invade Japanese-occupied Burma at several widely separated points. The Japanese forestalled them by launching their own offensive into India, and this offensive became larger in scope than originally intended. By the end of the year, the Allies had achieved significant territorial gains only in one sector, the extreme north-east of Burma, but the Japanese attack on India had been defeated with very heavy casualties. This handicapped the Japanese attempts to defend Burma against renewed Allied offensives in the following year.

Rival plans Allied plans After the Japanese invasion of Burma in early 1942, the Allies had launched tentative counterattacks in late 1942 and early 1943, despite lack of preparation and resources. This resulted in an Allied defeat in the coastal Arakan Province of Burma, and a questionable success in the first Chindit long-range raid into Burma (codenamed Operation Longcloth).

In August 1943 the Allies created South East Asia Command (SEAC), a new combined command responsible for the South-East Asian Theatre. Its Commander in Chief was Admiral Louis Mountbatten. This brought a new sense of purpose and in November, when SEAC took over responsibility for Burma, the newly formed British Fourteenth Army was ready to take the offensive. The substantial improvement in the effectiveness of the troops which Fourteenth Army inherited has been credited to its commander, Lieutenant General William Slim. He enforced the use of anti-malarial drugs as part of an emphasis on individual health, established realistic jungle warfare training, rebuilt the army's self-respect by winning easy small-scale victories and developed local military infrastructure.Keegan, pp.243-255

Slim's efforts were aided by improvements to the Allied lines of communication. By October 1944, capacity on the North-East Indian Railways had been raised from 600 tons a day at the start of the war to 4,400 tons a day. The Allied Eastern Air Command, which consisted mainly of Royal Air Force squadrons but also several units of the Indian Air Force and bomber and transport units of the United States Army Air Forces (USAAF), had gained air superiority and this allowed the Allies to employ new tactics, relying upon air support and aerial resupply of troops.

SEAC had to accommodate several rival plans: Admiral Mountbatten, as a naval officer who had previously served as commander of Combined Operations HQ, favoured amphibious landings. The first of these was to be on the Andaman Islands (Operation "Buccaneer"), but the landing craft assigned to the operation were recalled to Europe in preparation for the Normandy Landings. The previous year, a British attack into the Burmese coastal province of Arakan had been heavily defeated. Having been reorganised, XV Corps had taken over this part of the front and was preparing to renew the offensive with the aim of capturing Akyab Island, important for its port and airfield. A limited amphibious move (Operation "Pigstick") in support of this attack had to be abandoned for lack of the necessary landing craft and other shipping.

The American aim in the China Burma India Theater was to maintain military aid and supplies to the Republic of China under Chiang Kai-shek, with its wartime capital in Chungking. They had established an air supply route, known as the Hump, over the Himalayas to Kunming in the Chinese province of Yunnan. Some Chinese forces which had retreated into India in early 1942 had been re-equipped and retrained by an American military mission under Lieutenant General Joseph Stilwell, who was also Chief of Staff to Chiang Kai-shek and Deputy Commander of SEAC. Stilwell proposed to construct a new road, the Ledo Road, to link India and China by land, although British leaders were sceptical about the value of this road and the effort devoted to it. By the start of 1944, the new road had reached the far side of the Patkai mountains, and Stilwell was preparing to advance on Kamaing and Myitkyina in northern Burma. Chiang Kai-shek had agreed to mount an offensive across the Salween River into eastern Burma from Yunnan. When the Andaman Island landings were cancelled, he claimed this was a breach of faith and cancelled the Yunnan offensive,McLynn, pp.226-227 although he later reinstated it. After a long-distance raid (Operation "Longcloth") in 1943 by a long-range penetration force known as the Chindits, British Major-General Orde Wingate had gained approval for the force and its scope of operations to be greatly expanded. This was opposed by Slim and others who felt that this was too great a drain on manpower and resources, but under political pressure from Winston Churchill, Wingate's plans went ahead. The Chindits, designated Indian 3rd Infantry Division for cover purposes, were to assist Stilwell by disrupting the Japanese lines of supply to the northern front. Wingate had originally planned that an airborne brigade would capture a Japanese-held airfield at Indaw, which would then be garrisoned by a line infantry division as a base for further Chindit raids. This second part of the plan for Wingate's Special Force, which would have imposed heavy demands on the available transport aircraft and also required troops already allocated to other operations, was later dropped.Slim, p.218McLynn, pp.265-266

After protracted staff discussions within India and between the Allied staffs and commanders in London, Washington and Chungking, the Allied plans for 1944 were reduced to: the offensive by Stilwell's Chinese troops from Ledo; the Chindit operation in support of Stilwell; the renewed overland attack in Arakan; and a rather ill-defined offensive across the Chindwin River from Imphal in support of the other operations.

Japanese plans About the same time that SEAC was established, the Japanese had created a new headquarters, Burma Area Army, commanded by Lieutenant General Masakazu Kawabe. Its subordinate formations were the Japanese Fifteenth Army in the north and east of Burma and the Japanese Twenty-Eighth Army in the south and west.

By chance or design, the new commander of Fifteenth Army, Lieutenant General Renya Mutaguchi, had played a major part in many recent Japanese triumphs. He had for example been the officer immediately concerned in the Marco Polo Bridge Incident in 1937, which started hostilities between Japan and China, and stated his belief that it was his destiny to win the war for Japan.Allen, p.154 He was keen to mount an offensive against India. Burma Area Army originally quashed this idea, but Mutaguchi's persistent advocacy won over officers at Southern Expeditionary Army Group at Singapore, the HQ of all Japanese forces in southern Asia. Finally, Imperial General Headquarters in Tokyo approved Mutaguchi's plan. Officers who opposed Mutaguchi's plans were transferred or sidelined.Allen, pp.164-165 Neither Kawabe, nor Field Marshal Hisaichi Terauchi, the commander in chief of Southern Expeditionary Army Group, were given any opportunity to veto Mutaguchi's plan, or to control the operation once it had started.

The Japanese were influenced to an unknown degree by Subhas Chandra Bose, commander of the Indian National Army. This was composed largely of Indian soldiers who had been captured in Malaya or Singapore, and some Tamil labourers living in Malaya. At Bose's instigation, a substantial contingent of the INA joined in this Chalo Delhi ("March on Delhi"). Both Bose and Mutaguchi emphasised the advantages which would be gained by a successful attack into India. With misgivings on the part of several of Mutaguchi's superiors and subordinates, Operation U-Go was launched.Allen, pp. 157-170

Northern front

Stilwell's forces, the Northern Combat Area Command, initially consisted of two American-equipped Chinese divisions, with a Chinese-manned M3 Light Tank battalion and an American long-range penetration brigade known after its commander as "Merrill's Marauders". Three Chinese divisions were later flown from Yunnan to Ledo to reinforce Stilwell.

In October 1943 the Chinese 38th Division, led by Sun Li-jen, began to advance from Ledo towards Shinbwiyang, while American engineers and Indian labourers extended the Ledo Road behind them. The Japanese 18th Division advanced to the Chindwin to stop them, but found itself outmatched. Whenever the Chinese 22nd and 38th Divisions ran into Japanese strong points, the Marauders were used to outflank Japanese positions by going through the jungle. A technique which had served the Japanese so well earlier in the war before the Allies had learnt the arts of jungle warfare was now being used against them. At Walawbum, for example, if the Chinese 38th Division had been a little swifter and linked up with the Marauders it could have encircled the Japanese 18th Division.

Not only were the Japanese driven back, but the Allies were able to use the trace of the track the Japanese had constructed to supply 18th Division, to speed their construction of the Ledo Road.

Second Chindit Expedition In Operation Thursday the Chindits were to support Stilwell's advance by interdicting Japanese supply lines in the region of Indaw. On 5 February 1944, Brigadier Bernard Fergusson's 16th Brigade set out from Ledo, on foot. They crossed exceptionally difficult terrain which the Japanese had not guarded, and penetrated the Japanese rear areas. In early March, three other brigades were flown into landing zones behind Japanese lines by the USAAF 1st Air Commando Group, from where they established strongholds on most of the Japanese road and rail links to their northern front. Over the next two and a half months the Chindits were involved in many very heavy battles with the Japanese.

Brigadier Michael Calvert's 77th Brigade successfully defended one of the landing zones, codenamed "Broadway", and established a road and railway block at Mawlu, north of Indaw. This position, codenamed the "White City", was successfully held for several weeks. Not all communications to the Japanese northern front were blocked, as only a single Chindit battalion operated against the road from Bhamo to Myitkyina, beyond the range of effective Allied air support.

On 24 March, Fergusson's brigade attempted to capture the airfield at Indaw but was repulsed, after which the exhausted brigade was withdrawn to India. On the same day, Wingate, the commander of the Chindits, was killed in an aircrash. His replacement was Brigadier Joe Lentaigne, formerly the commander of the 111th Brigade, one of the Chindit formations.

On 17 May, overall control of the Chindits was transferred from Slim's Fourteenth Army to Stilwell's NCAC. The Chindits evacuated "Broadway" and the "White City", and moved from the Japanese rear areas to new bases closer to Stilwell's front. They were given additional tasks for which they were not equipped. At the same time, the Japanese replaced the scratch "Takē Force" which had been trying to defend their rear areas with the newly formed headquarters of the Japanese Thirty-Third Army, and deployed 53rd Division against the Chindits.

The 111th Brigade, commanded by John Masters, tried to establish another road and rail block codenamed "Blackpool" near Hopin, but were forced to retreat on 25 May after 17 days of battle. The monsoon had broken, making movement difficult and preventing the other Chindit formations reinforcing Masters's brigade.