On 8 March 1944 the Japanese launched another and major offensive, U-go, which was intended to capture the British bases at Imphal and Kohima, as a preliminary to an advance on Chittagong. Mountbatten had already been convinced by numerous intelligence reports and aerial reconnaissance that the Japanese intended to strike at Imphal. Mountbatten was alarmed that neither General Sir George Giffard, Commander-in-Chief of 11th Army Group, nor Slim showed much urgency about reinforcing the Fourteenth Army in Imphal. It was Mountbatten who insisted on flying the 5th Indian Division from Arakan to Imphal, although the Official History states that Slim had already appealed for air transport as a matter of urgency. However, Troop Carrier Command was by now desperately overstretched and Mountbatten, ignoring Stilwell, informed the Chiefs of Staff that he was diverting 30 C-46 Commando and Dakota transports from US Air Transport Command operating over ‘the Hump’—he had already, with the reluctant agreement of the Combined Chiefs of Staff, borrowed transports from ‘the Hump’ to help the air supply to Arakan, but these had been returned. On 17 February, after an appeal from Churchill, the US Chiefs agreed to the transfer but Mountbatten had already taken over the aircraft on the 15th. Ronald Lewin commented that ‘Mountbatten is to be seen making the big, right judgment and thus enabling Slim to concentrate on the battle’. During the battle of Imphal the 5th Indian Division was moved from Arakan to Imphal complete with its guns, jeeps and mules between 19 and 29 March by Dakotas of 194 Transport Squadron RAF. The division’s airlift has been described as ‘a brilliant and successful improvisation which again demonstrated the confident flexibility of Slim’s staff and the determination of the air crews’.
Air Marshal Sir John Baldwin’s 3rd Tactical Air Force was responsible for all air operations on the Fourteenth Army Front. He decentralised close air support to small air staffs attached to each group headquarters in order to make liaison with the Army more effective. On 1 May Troop Carrier Command was placed under Baldwin’s authority, but deliveries to Imphal fell off in early May. Baldwin turned some airfields into single-commodity areas so that aircraft could be loaded to full capacity with one commodity. These measures led to a dramatic increase in supplies to Imphal during June, despite the huge strain on the air crews with difficult flying conditions and air crews operating to the limits of their endurance. Imphal Ground Control played a crucial role in ensuring that the airlift went as smoothly as possible under trying circumstances. Earlier in the fighting at Imphal, General G. A. P. Scoones, Commander of IV Corps, suggested to the AOC of 221 Group, Air Vice-Marshal S. F. Vincent, based at Imphal, that he should move his units from the valley and operate from greater safety further back. Vincent refused, pointing out that he had done enough retreating from the Japanese and that he and his men would remain at Imphal where their presence was essential to the supply operation.
Kohima was another crucial strategic position, situated as it was on the summit of the pass linking north-east India with Burma. In April the Japanese had besieged the Allied garrison there and the RAF had enormous problems in giving close air support and dropping supplies in the face of air pockets and sudden mists and the risk of being shot at from close range from Japanese positions close to the garrison.
Given the strain on the transport planes imposed by these operations, and the requirement to supply and support Wingate’s second Chindit campaign, Operation Thursday, Slim’s decision to fly part of General F. W. Messervy’s 7th Indian Division from Arakan further to reinforce Imphal clearly required more transport planes. Accordingly, on 25 March, Mountbatten appealed to the Joint Chiefs of Staff for a further 70 Dakotas and the authority to retain the commandos he had taken from ‘the Hump’. On 29 March the CCoS agreed to the temporary transfer to Mountbatten’s command of 64 US and 25 RAF Dakotas from the Mediterranean and Middle East, as well as the retention of the planes from ‘the Hump’. On 28 April, however, Washington demanded that the planes borrowed from the Middle East be returned by mid-May. This would have been disastrous for the Burma campaign, and Mountbatten faced an uphill struggle in his efforts to retain them. Although Washington offered to replace them by Dakotas from the United States, Mountbatten realised such replacements would be useless given that their inexperienced pilots would have had no training in the navigational and technical skills required in monsoon and mountainous conditions. He refused to let the Middle East planes go and eventually Washington relented and allowed him to retain the Middle East planes initially until 31 May and later until 16 June. Nevertheless, as Probert points out, supplies to Imphal were maintained by only a narrow margin. The battles of Imphal and Kohima ended on 22 June when the British Army reopened land communications and destroyed the Japanese Army in the area.
Intensive Allied air operations over north Burma and attacks on Japanese airfields in southern Burma by USAAF General H. C. Davidson’s Strategic Air Force equipped with Liberators (B. 24) and Mitchells (B. 25) achieved air superiority by the end of March, although in April Japanese fighters and bombers were able to resume daylight raids on Imphal but these were defeated by the RAF’s adoption of air patrols which enabled the Spitfires to intercept the attackers, whose efforts steadily diminished over the next three months. The airlift of supplies to Imphal, Kohima and other threatened sectors by Eastern Air Command continued unimpeded by these Japanese attacks. Of great importance during the campaign was that non- combatants and the sick and wounded could be flown out of Imphal and Kohima. Both Mountbatten and Slim insisted that this was essential if the spread of disease in the garrisons was to be contained. Slim wrote: ‘air evacuation, in the long run, probably made the greatest difference of all to the wounded and sick’.
Meanwhile Wingate’s special forces had landed deep in the interior of Burma to harass Japanese communications, especially the Mandalay—Myitkyina railway, by establishing strong points in occupied territory—the latter likely to deprive the Chindits of the mobility which had been the key to what they had achieved in Chindit 1. The need to fly in the bulk of the Chindits and keep them supplied once they had landed strained the air transport resources of SEAC to the maximum. Wingate demanded more Dakotas to support his operations but Slim rejected his request—they could not be spared. Wingate was killed in an air crash on 24 March 1944. Military historians and soldiers continue to argue about his achievements—Slim wrote later: ‘… I do not believe that the contribution of Special Forces was either great in effect or commensurate with the resources it absorbed’ —but there is no doubt that Wingate was an inspiring leader and most of his men were devoted to him. After his death the Chindits’ operations continued, latterly in support of the advance of Stilwell and the Chinese forces who succeeded in capturing Myitkyina airfield on 7 May 1944, again using air transport to sustain the campaign.
General Sir Montagu Stopford’s XXXIII Corps now began to advance towards the Chindwin in monsoon conditions. Slim hoped to use the Chindwin as a base for an advance on Mandalay and Rangoon in the next dry season. However, General A. C. Wedemeyer, Mountbatten’s former Deputy Commander, who had been transferred to Chungking to take over from Stilwell after the latter had been relieved of his command in October 1944, suddenly ordered the diversion of three squadrons of Dakotas (75 planes) in December to airlift Chinese divisions to China to defend Chennault’s 14th Air Force airfields from a Japanese offensive. At first Mountbatten’s protests were overruled by the Chiefs of Staff, but, eventually, after much pressure from Mountbatten, Wedemeyer, on 1 February 1945, returned two of the squadrons while the British diverted transport planes from other theatres to Burma. Finally Mountbatten persuaded the Combined Chiefs of Staff to let him retain the two squadrons until 1 June or until the fall of Rangoon, ‘whichever date is earlier’. This was crucial since Slim’s advance on Mandalay, which fell to his forces on 9 March, and then on Rangoon, depended totally on air supply. Vincent reported to Mountbatten on 23 February 1945 that the close tactical air support which his squadrons provided had made up for the shortage of artillery which the terrain made difficult to move up. He continued: ‘Almost every aeroplane exceeded the maximum degree [of operational intensity laid down by the Air Ministry] for six consecutive months—a wonderful effort of the pilots and the ground crews and also of the aircraft depots back in India which kept us supplied with remarkably little waiting.’ The aircraft dropped not only food, ammunition, fodder and water but also mail, drugs, boots, the SEAC newspaper, typewriter ribbons, socks, toothbrushes, razors, spectacles and even rum. Rangoon, which the Japanese had evacuated, fell to the Allies on 2 May 1945. Apart from mopping-up operations, many of which still involved ferocious air and land fighting, that was the end of the campaign—the Japanese armed forces surrendered to the British in Singapore on 12 September 1945 (they had already formally surrendered to MacArthur at Tokyo on 2 September). The Japanese collapse came at a fortunate time since it appeared that the Air Ministry was more anxious for the Royal Air Force to participate in the US bombing campaign against Japan than in providing up-to-date bombers to pave the way for Mountbatten’s invasion of Malaya.
Although, as Ronald Lewin points out, Mountbatten was ‘not free from error’, the leadership qualities of Mountbatten during the Burma campaign were not in doubt, especially in his overall responsibility for air. Despite his criticisms of Mountbatten’s occasional impulsiveness and failure to consult staff before issuing directives, Pownall wrote on 14 September 1943 that ‘Mountbatten, aged 43, will certainly have all the necessary drive and initiative to conduct this war’. In November Pownall found that ‘his energy and drive are most admirable features’. He certainly galvanised the lethargic Indian organisations, and his most important contribution to victory was in securing from the United States much needed transport planes in the face of US obstruction. Stratemeyer, who loyally supported Mountbatten during the Burma campaign, described him as ‘An outstanding example of how an Allied Air Commander should conduct himself. Andrew Gilchrist of the British Foreign Office, who was on active service in South-East Asia between 1944 and 1945, wrote: ‘When I think of the handicaps under which Mountbatten laboured—repeated hold-ups of promised man-power supplies and shipping, fantastic political entanglements due to American policy in China—I am amazed that so much was done.’ Of the other air leaders, Peirse’s deputy, Sir Guy Garrod, who took over the Command temporarily until the arrival of Park in late February, was responsible for the planning of air operations which contributed so crucially to the Allied victories in Burma in early 1945. Stratemeyer described Garrod as ‘a natural commander and leader… he’s a great guy’. This compliment could also be applied to Air Vice-Marshal S. F. Vincent who led 221 Group at Imphal with conspicuous success. Air Commodore the Earl of Brandon, who took over 224 Group in July 1944, was highly respected by his men and by other service commanders, although his unorthodox ways frequently upset senior officers. In the struggle over Mandalay he removed his air rank badges and flew operational sorties with 273 Squadron as a flying officer. Mountbatten also received the full support of General Raymond Wheeler, US Army, his principal administrative officer and an expert on logistics. Mention should also be made of Air Vice-Marshal T. M. Williams, who replaced Stevenson as AOC Bengal in January 1943. Slim described Williams as ‘an inspiring commander… who laid the foundations of the air supremacy we subsequently gained’. Another daring leader was USAAF General Old of Troop Carrier Command who often led sorties himself.
Despite Pownall’s complaint in April 1944 that the Strategic Air Force was attacking Japanese lines of communication instead of their more crucial aerodromes and shipping and that ‘It’s the old game of “the separate war” of the Air Force’, the record shows that, for the most part, co-operation between air and ground commanders was close and cordial, as was co-operation between USAAF and RAF units. This was largely due to the leadership qualities of both Slim and Baldwin who worked closely together at Comilla earlier in the campaign. Nor should be forgotten the tenacity and courage of air crews throughout the campaign who frequently flew to the limits of their endurance to sustain the ground campaign. They were rightly praised by Sir George Giffard in a letter to Slim on 28 July:
I have not forgotten the immense debt which the Army owed to the Air. It is no exaggeration to say that without the magnificent assistance given by the Eastern Air Command, the Army could never have won its victories. I am sure that no one who watched them is ever likely to forget the courage, determination and skill of all the aircraft pilots and crews who have flown in the worst weather in the world over appalling country either to attack the enemy in front of the Army and his communications in the rear with bombs and machine guns or to deliver reinforcements, supplies, ammunition etc to the troops isolated in Arakan, Imphal and Central Burma.