Operation Battle of Imphal

The 'Battle of Imphal' was fought between Japanese and British forces in the area round the city of Imphal, the capital of the state of Manipur in north-eastern India (8 March/3l July 1944).

The Japanese sought to destroy the Allied forces at Imphal and thereby pave the way for an invasion of India proper, but were defeated and driven back into Burma after suffering enormous losses. Together with the simultaneous 'Battle of Kohima' on the road by which the encircled Allied forces at Imphal were relieved, the battle was the turning point of the Burma campaign. Their defeat at Kohima and Imphal was the largest land reverse suffered by the Japanese up until that time, and many of the Japanese deaths resulted from starvation, disease and exhaustion suffered during their retreat.

In March 1943, the Japanese command structure in Burma had been reorganised. A new headquarters, the Burma Area Army, was created under the command of Lieutenant General Masakazu Kawabe, and one of its subordinate formations, responsible for the central part of the front facing Imphal and Assam, was the 15th Army under the command of Lieutenant General Renya Mutaguchi. From the moment he assumed command, Mutaguchi forcefully advocated an invasion of India. His motives for doing so appear uncertain: he had played a major part in several Japanese victories, ever since the Marco Polo Bridge incident in China during 1937, and believed it was his destiny to win the decisive battle of the war for Japan; he may also have been goaded by the 'Longcloth' first Chindit expedition, a raid behind Japanese lines launched by the British under Brigadier O. C. Wingate early in 1943. The Allies had widely publicised the successful aspects of Wingate’s expedition while concealing their losses to disease and exhaustion, possibly leading Mutaguchi and some of his staff to underestimate the difficulties they would later face.

At the start of 1944, the war was going against the Japanese on several fronts. They were being driven back in the central and south-western Pacific, and their merchant ships were under increasingly devastating attack by Allied submarines and aircraft. In South-East Asia, they had held their lines over the preceding year, but the Allies were preparing several offensives into Burma from India and the Chinese province of Yunnan. In particular, the town of Imphal in Manipur on the frontier with Burma was built up to be a substantial Allied logistic base, with airfields, encampments and supply dumps. Imphal was linked to an even larger base at Dimapur in the Brahmaputra river valley by a road which wound 100 miles (160 km) through the steep and forested Naga Hills.

Mutaguchi intended to exploit his planned capture of Imphal by advancing to the Brahmaputra river valley. This would cut the Allied lines of communication to the front in northern Burma, where the US-led Northern Combat Area Command was attempting to construct the 'Ledo Road' to link India and China by land, and to the airfields supplying the Nationalist Chinese forces under Chiang Kai-shek via an airlift over 'The Hump' (the Himalaya mountains). Although the staffs at the Burma Area Army and at Field Marshal Count Hisaichi Terauchi’s Southern Expeditionary Army Group (the supreme command for the Japanese forces in South-East Asia and the southern Pacific) had reservations about the overly ambitious scale of Mutaguchi’s proposed operation, they were eventually won over by his persistent advocacy. Finally, Prime Minister Hideki Tojo and the Imperial General Headquarters gave their approval to the plan.

Mutaguchi intended to isolate and destroy the Allied units in their forward positions and then capture Imphal. His plan was named 'U' (ii). In this plan, the

Lieutenant General Genzo Yanagida’s 33rd Division was to surround and destroy Major General D. T. Cowan’s Indian 17th Light Division at Tiddim, then attack Imphal from the south. The 'Yamamoto' Force, formed of units detached from the 33rd Division and 15th Division under Major General Tsunoru Yamamoto, commander of the 33rd Division's infantry group), would destroy Major General D. D. Gracey’s Indian 20th Division at Tamu, then attack Imphal from the east. The force was supported by the 14th Tank Regiment equipped with 66 assorted tanks, under the command of Lieutenant Colonel Nobuo Ueda, and the 3rd Heavy Artillery Regiment under the command of Lieutenant Colonel Kazuo Mitsui. Lieutenant General Masafumi Yamauchi’s 15th Division was to envelop Imphal from the north. This last division was still arriving from road-building duties in Thailand and was understrength at the start of the operation.

In a separate but subsidiary operation, Lieutenant General Kotoku Sato’s 31st Division was to isolate the Imphal area by capturing Kohima on the road linking Imphal and the railhead at Dimapur, and then advance on the latter.

At the insistence of Subhas Chandra Bose, leader of the Azad Hind movement, which sought to overthrow British rule in India by force with Japanese assistance), the Indian National Army made a substantial contribution: originally, the Japanese had intended to use the Indian National Army only for reconnaissance and propaganda. Units of the 1st Division (initially the Subhas Brigade or 1st Guerrilla Regiment, less one battalion sent to the Arakan western coast region of Burma), was to cover the left flank of the 33rd Division's advance.The 2nd Guerrilla Regiment was attached later in the battle to the 'Yamamoto' Force. The Special Services Group, redesignated as the Bahadur Group was to operate in the scouting role and provide pathfinders with the Japanese advanced units in the opening stages of 'U' (ii), and was tasked to infiltrate through British lines and encourage elements of the British Indian army to defect.

All of Mutaguchi’s divisional commanders disagreed with the plan to some extent. Sato distrusted Mutaguchi’s motives, and Yanagida openly derided his superior as a 'blockhead'. Yamauchi was already very ill and fatalistic. The opponents of Muragichi’s plan ghad as their primary reservation the matter od supply. Mutaguchi assumed that success would be achieved within three weeks, but adequate supplies after that period could be obtained only if the Japanese captured Allied supply dumps, as the monsoon rains, which usually descended from about the middle of May, made the supply routes from the Chindwin river area almost impossible to traverse. Gambles such as Mutaguchi was making had worked in the past, but might no longer be valid given nearly total British air superiority in the area, as well as the improvement in morale and training of British and Indian troops. Mutaguchi proposed to use 'Genghis Khan' rations, driving herds of buffalo and cattle, which were to be gathered throughout northern Burma, across the Chindwin river as meat rations 'on the hoof'. However, most of these beasts died from lack of forage and their meat rotted many miles from the troops they were intended to feed.

There were other weaknesses in the plan, and these became increasingly evident as the campaign progressed. The Japanese assumed that the British would be unable to use tanks on the steep jungle-covered hills around Imphal. For ease of movement and supply, the Japanese left behind most of their field artillery, which was their chief anti-tank weapon, and as a result the Japanese troops had little protection against tanks.

Based on his experiences in the campaigns in Malaya and Singapore and in the Japanese conquest of Burma in early 1942, Mutaguchi dismissed British and Indian troops as inherently inferior. What Mutaguchi ignored, however, was the fact that the troops he had met on those occasions had generally been inadequately trained and were poorly led. The Allies had by now largely overcome the administrative and organisational problems which had crippled their early efforts in Burma, and their troops were far better trained and motivated.

Imphal was held by Lieutenant General G. A. P. Scoones’s Indian IV Corps. The corps was in turn part of Lieutenant General W. J. Slim’s British 14th Army As the British were themselves planning to take the offensive, the corps' units were thrown forward almost to the Chindwin river, were widely separated, and were therefore vulnerable to cut off and surrounded.

Major General D. D. Gracey’s Indian 20th Division was holding Tamu, 68 miles (110 km) to the south-east of Imphal. The division was untried but well-trained. Major General D. T. Cowan’s Indian 17th Light Division was occupying Tiddim, 151 miles (243 km) to the south of Imphal, at the end of a long and precarious line of communication. The division, which had only two brigades, had been intermittently in action since December 1941. Major General O. L. Ouvry’s Indian 23rd Division was in reserve in and around Imphal. It had served on the Imphal front for two years and was severely understrength as a result of endemic diseases such as malaria and typhus. Brogadier M. Hope-Thompson’s Indian 50th Parachute Brigade was to the north of Imphal as it undertook advanced jungle training. Brigadier R. L. Scoone’s Indian 254th Tank Brigade was stationed in and around Imphal.

The Indian divisions were composed of both British and Indian personnel on an approximately 1/2 ratio in fighting men. In each brigade, there were generally single British, Gurkha and Indian battalions, although two brigades (the 37th Brigade in the 23rd Division and the 63rd Brigade in the 17th Division) were composed entirely of Gurkha units. Each division was supported by two field artillery regiments (usually British) and one Indian mountain artillery regiment.

Late in February, a local Japanese counterattack was launched as 'Ha' (iv) against Lieutenant General A. F. P. Christison’s Indian XV Corps in the Arakan region, using much the same tactics as Mutaguchi proposed to employ. The engagement became known to the Allies as the 'Battle of the Admin Box', and failed when Allied aircraft parachuted supplies to isolated troops, allowing them to stand firm, while the Japanese who had infiltrated behind them ran out of supplies. From this point onward, the Allies came to rely increasingly on their transport aircraft. Also, the Japanese unexpectedly encountered a number of Indian-manned tanks, to which the lightly equipped infiltrators had little counter. The planning of 'U' (ii) was by now too far advanced for account to be taken of these developments.

Even as the Japanese prepared to launch their offensive, the Allies began the initial airborne phase of their 'Thursday second Chindit expedition on 5 March 1944. Japanese officers such as Major General Noburo Tazoe, commanding the Imperial Japanese army air force units in Burma, urged Mutaguchi to divert troops from his offensive to secure the Japanese rear areas against the Chindits. Mutaguchi dismissed these concerns, however, claiming that in a few weeks he would occupy the air bases from which the Chindits were being supplied.

When they received intelligence that a major Japanese offensive was imminent, Slim and Scoones planned to withdraw their forward divisions onto the Imphal plain and force the Japanese to fight at the end of impossibly long and difficult lines of communication. The British commanders misjudged the date on which the Japanese were to attack, however, and the strength that the Japanese would commit against some objectives. The Japanese troops began to cross the Chindwin river on 8 March, but Scoones gave his forward divisions orders to withdraw to Imphal only on 13 March.

The Indian 20th Division held Tamu near the Chindwin river, and Moreh a short distance to the north, where a large supply dump had been established. On 20 March there was a clash between six US-supplied Grant medium tanks of the 3rd Carabiniers and six Type 95 Ha-Go light tanks leading Yamamoto’s advance from the south. The lighter Japanese tanks were destroyed. Gracey was opposed to making any retreat, but on 25 March he was ordered to detach part of his division to provide a reserve for the IV Corps. As this left the division too weak to hold Tamu and Moreh, it withdrew to the Shenam Saddle, a complex of hills through which ran the road linking Imphal and Tamu. The supply dump at Moreh was set ablaze, and 200 cattle there were slaughtered. The division fell back without difficulty, mainly because two of the battalions of the 'Yamamoto' Force from the 15th Division (the 2/51st Regiment and 3/60th Regiment) were delayed at Indaw in northern Burma by the Chindits and were unable to intervene.

Farther to the south, the Indian 17th Light Division was cut off by the 33rd Division. Patrols from the division and from 'V' Force (an irregular force of locally raised levies and guerrillas) warned Cowan of a Japanese force advancing against the rear of the division as early as 8 March, allowing Cowan to regroup the division to protect its rear. On 13 March, the 215th Regiment attacked a supply dump at Milestone 109, 2- miles (32 km) behind Cowan’s leading outposts, while the 214th Regiment seized Tongzang and a ridge named Tuitum Saddle across the road a few miles behind the Indian 17th Division’s main position. The Indian division began to withdraw on 14 March. At Tuitum Saddle, the 214th Regiment were unable to dig in properly before it was attacked by Brigadier R. C. O. Hedley’s Indian 48th Brigade on 15 March. The Japanese suffered heavy casualties and were forced away from the road. Farther to the north, the Japanese captured the depot at Milestone 109 on 18 March, but Indian troops retook this on 25 March. Cowan had taken steps to secure the most vulnerable point in the rear of his division, the bridge over the Manipur river. The division’s rearguard crossed safely on 26 March, demolishing the bridge behind them. The division removed most of the vehicles, food and ammunition from the depot at Milestone 109 before resuming its retreat.

Both the Japanese and the Indian divisions had suffered heavy casualties. Yanagida, commander of the 33rd Division, was already pessimistic, and was apparently unnerved by a garbled radio message which suggested that one of his regiments had been destroyed at Tongzang. He therefore did not press the pursuit against the Indian 17th Light Division, and advanced cautiously despite reprimands from Mutaguchi.

Scoones had nevertheless been forced to send the bulk of his only reserve, Roberts’s Indian 23rd Division, to the aid of the Indian 17th Light Division. The two divisions, supplied by parachute drops from Allied aircraft, made their way back to the Imphal plain, which they reached on 4 April.

Meanwhile, Imphal had been left vulnerable to Yamauchi’s 15th Division. The only force left covering the northern approaches to the base, the Indian 50th Parachute Brigade, was roughly handled in the 'Battle of Sangshak' by a regiment of Sato’s 31st Division on its way to Kohima. The 60th Regiment cut the main road a few miles to the north of Imphal on 28 March, while the 51st Regiment advanced on Imphal from the north-east, down the valley of the Iril river and a track from Litan, 23 miles (37 km) to the north-east of Imphal.

However, the earlier diversionary attack launched by the 55th Division in the Arakan region had already failed. Admiral the Louis Mountbatten, the commander-in-chief of the South East Asia Command, had taken steps to secure US transport aircraft normally assigned to the airlift over 'The Hump' to China, and Slim was able to call on these for the movement of Major General G. C. Evans’s battle-hardened Indian 5th Division, including all its artillery and first-line transport (Jeeps and mules), by air from the Arakan region to the central front. The move was completed in only 11 days. One brigade and a mountain artillery regiment went to Dimapur in the Brahmaputra river valley, but the other two brigades, the field artillery and the divisional headquarters were delivered to Imphal. The leading troops of the division were in action north and east of Imphal on 3 April.

On the Japanese left flank, the Indian National Army's Subhas Brigade, led by Shah Nawaz Khan, reached the edge of the Chin Hills below Tiddim and Fort White at the end of March. From this position, the 2/Subhas Brigade sent companies to relieve the Japanese forces at Falam and to Hakha, from where in turn Khan’s forces sent out patrols and laid ambushes for the Chin guerrillas under the command of a British officer, Lieutenant Colonel Oates, taking a number of prisoners. In the middle of May, a force under Khan’s adjutant, Mahboob Ahmed, attacked and captured the hill-top fortress of Klang Klang. the 3/Subhas Brigade meanwhile moved to the area of Fort White and Tongzang in premature anticipation of the destruction of Major General F. W. Messervy’s Indian 7th Division in the Arakan, which would allow it to receive volunteers.

During the early part of the offensive, the Bahadur Group apparently achieved some success in inducing British Indian soldiers to desert.

From the beginning of April, the Japanese attacked the Imphal Plain from several directions. The 33rd Division attacked from the south at Bishenpur, where it cut a secondary track from Silchar into the plain. A commando raid destroyed a suspension bridge, making the Silchar track unusable. The Indian 17th Light Division and Indian 23rd Division were regrouping after their retreat, and Bishenpur was held only by Brigadier D. A. L. Mackenzie’s Indian 32nd Brigade detached from the Indian 20th Division. The Japanese advanced through the hills to the west of Bishenpur, almost isolating the British in the village, but suffered severely from British artillery fire. Their leading troops were halted by lack of supply only 10 miles (16 km) from Imphal. Other Japanese advancing directly up the road linking Tiddim and Imphal were halted in Potsangbam 2 miles (3.2 km) to the south of Bishenpur, as troops of the Indian 17th Light Division rejoined the battle.

Yanagida had already infuriated Mutaguchi by his caution, and was finally relieved of command at the end of the month and replaced by Lieutenant General Nobuo Tanaka, an altogether more forceful officer who had previously commanded the [e[29th Independent Mixed Brigade in Thailand.

The 'Yamamoto' Force attacked the Shenam Saddle, defended by the main body of the Indian 20th Division, on the main road linking Tamu and Imphal. This was the only metalled road the Japanese could use, and it was vital for them to break through to allow Yamamoto’s tanks and heavy artillery to attack the main defences around Imphal itself. Only a few miles to the north of the saddle was Palel airfield, one of the only two all-weather airfields in the plain, and vital to the defenders.

A Japanese attack up the road on 4 April suffered from a lack od co-ordination: the infantry were not ready to take part, and 12 Japanese tanks were caught exposed on the road by British anti-tank guns.Between 8 and 22 April there was heavy fighting for five peaks commanding the road to the east of the Saddle. The Japanese captured a number of them, but Indian and British counterattacks regained some of these. Casualties were heavy on both sides.

Having failed to break through using the road, Yamamoto sent some troops through the rough terrain to the north of the Saddle to raid Palel airfield. The Indian National Army's two-battalion Gandhi Brigade (2nd Guerrilla Regiment), led by Inayat Kiyani, took part in this attack and on 28 April attacked Palel. The dissident Indians tried to induce some loyal Indian defenders to surrender, but the defenders rallied after initial hesitation. Another Indian National Army detachment carried out demolitions around Palel, but withdrew after it failed to rendezvous with Japanese units. The Gandhi Brigade was short of rations, having brought forward supplies for only one day, and also lost 250 casualties to shellfire after it pulled back from Palel.

The 15th Division encircled Imphal from the north. Its 60th Regiment captured a British supply dump at Kanglatongbi on the main ro9ad linking Imphal and Dimapura few miles to the north of Imphal, but the depot had been emptied of food and ammunition.

One battalion of Colonel Kimio Omoto’s 51st Regiment seized the vital Nungshigum Ridge, which overlooked the main airstrip at Imphal. This was a major threat to the IV Corps, and on 13 April the Indian 5th Division counterattacked with strong air support, massed artillery and the Grant tanks of B Squadron of the 3rd Carabiniers. The Japanese had expected that the slopes were too steep for tanks to climb, and indeed Grant tanks had never before been tried in action on such gradients. The Japanese regiment had very few effective anti-tank weapons, and their troops were driven from the ridge with heavy losses. The attackers also lost heavily; every officer of the Carabiniers and the attacking infantry (1/17th Dogra Regiment) being killed or wounded.

By 1 May, all Japanese attacks had come to a halt, and Slim and Scoones began a counterattack against the 15th Division, which was the weakest of the Japanese formations: should it be defeated, the siege would be broken once Kohima had also been recaptured. The progress of the British-led counterattack was slow, for the monsoon had broken, making movement very difficult. Moreover, the IV Corps was suffering a number of shortages and although rations and reinforcements were delivered to Imphal by air, artillery ammunition had to be conserved as it was too heavy for mass delivery be air.

The Indian 5th Division, now joined by Brigadier W. A. Crowther’s Indian 89th Brigade that was delivered by air to replace the brigade sent to Kohima, and the Indian 23rd Division, which was later replaced by the Indian 20th Division, attempted to capture the steep ridges, such as the Mapao Spur, held by the Japanese, but found these to be almost impregnable. Allied artillery was usually unable to hit Japanese positions on the reverse slopes, and the troops often stormed the summits of the ridges, only to be driven off by mortar fire and grenades from the reverse slope positions. The IV Corps regrouped. The Indian 23rd Division took over the defence of the Shenam Saddle, while from the end of May the Indian 5th Division concentrated on driving to the north from Sengmai up the main road through Kanglatongi, while the Indian 20th Division advanced along the tracks and the Iril river toward Litan and Ukhrul, threatening the 15th Division's lines of communication.

By this time, the Japanese were at the end of their endurance. Neither the 31st Division fighting at Kohima nor the 15th Division had received adequate supplies since the offensive began, and their troops were starving. Sato, commander of the 31st Division, ordered a retreat at the end of May so that his division could find food, and this made it possible for Lieutenant General M. G. N. Stopford’s Indian XXXIII Corps to drive the Japanese from Kohima, and advance to the south.

The men of the 15th Division were forced to abandon their defensive positions in order to scavenge for supplies in local villages or on the Japanese lines of communication. Mutaguchi dismissed the mortally ill Yamauchi, replacing him with Lieutenant General Uichi Shibata, but this did not change matters. After driving rearguards of the 'Miyazaki' Group, an independent detachment of the 31st Division, and the 60th Regiment from their delaying positions on the road linking Dimapur and Imphal, the leading troops of the IV Corps and the XXXIII Corps met at Milestone 109, 10 miles (16 km) to the north of Imphal, on 22 June, and the siege of Imphal was raised.

Tp the south of Imphal, the Indian 17th Light Division had moved back into the line, facing the 33rd Division. During the first half of May, there were several Japanese air attacks on Bishenpur, and heavy fighting for the village of Potsangbam, 2 miles (3.2 km) to the south, in which the British lost 12 tanks. The surviving crews of the 3rd Carabiniers were later flown out of Imphal to be reconstituted in India.

Cowan planned to break the deadlock on this front by sending Hedley’s Indian 48th Brigade on a wide left hook into the Japanese division’s rear while Brigadier G. W. S. Burton’s Indian 63rd Brigade attacked them in front. The Japanese division’s temporary commander (its chief-of-staff, Major General Tetsujiro Tanaka) planned at the same time to infiltrate through Indian 17th Light Division’s front to seize vital objectives in the middle of the Indian positions. Both moves were launched almost simultaneously. The Gurkha battalions of the Indian 48th Brigade cut the road behind the Japanese on 18 May, but the Indian 63rd Brigade was unable to break through to link with its sister brigade, and Indian 48th Brigade was forced to fight its way through the Japanese positions to rejoin the division, with heavy losses. Meanwhile, some of Tanaka’s troops (the 214th Regiment) captured hills close to the Indian 17th Light Division’s headquarters on 20 May. Because of the incursion into their own rear, the Japanese were unable to reinforce their forward troops, and in the course of the following week the isolated Japanese were driven from their positions in the middle of the Indian division, many parties being wiped out.

A new and forceful commander, Tanaka took command of the 33rd Division on 22 May, and ordered repeated attacks which reduced many of his division’s battalions to mere handfuls of men. In June, he received reinforcements, in the form one one regiment from Lieutenant General Kaoru Takeda’s 53rd Division and a detachment of the 14th Tank Regiment, and used them to launch another attack. After initial success, the fresh regiment suffered heavy casualties from artillery fire. By the end of June, the 33rd Division had suffered so many casualties it could make no further effort.

'Yamamoto' Force had also suffered heavy casualties, but before withdrawing, launched two modest raids on Palel airfield in the first week of July, destroying several parked aircraft.

In the later part of May, the Indian Nation Army's 1st Guerrillas Regiment and 2nd Guerrilla Regiment, the latter commanded by Malik Munawar Khan Awan, had been redirected to Kohima. They moved to the north across the Japanese rear, but by the time they reached Ukhrul, the Japanese had already begun to withdraw. They decided instead to attack Imphal, and here both units suffered some desertions, but not on the scale that the commonwealth forces expected.[27]

It was as early as May that the Japanese had realised that the operation ought to be brought to a halt. Lieutenant General Hikosaburo Hata, the vice-chief of the Imperial General Staff, had made a tour of inspection of the Southern Area Army's headquarters late in April, and on his return to Tokyo reported pessimistically on the outcome of the operation at a large staff attended by General Hideki Tojo, the prime minister, who dismissed Hata’s concerns as their source was a junior staff officer, Major Masaru Ushiro of the Burma Area Army's headquarters. Messages were sent from Imperial General Headquarters, urging that the operation was to be fought to the end.

Kawabe travelled north from Rangoon to see the situation for himself on 25 May. Several officers whom he interviewed expressed confidence in success if reinforcements could be provided, but at the same time concealed the extent of the 15th Army's losses and the serious nature of the situation. At a meeting between Mutaguchi and Kawabe on 6 June, both used haragei, an unspoken form of communication using gesture, expression and tone of voice, to convey their convictions that success was impossible, but neither of the men wished to bear the responsibility of ordering a retreat. Kawabe subsequently became ill with dysentery and perhaps physically unfit for duty. He nevertheless ordered repeated attacks, stating later that Bose was the key to Japan’s and India’s future.

Mutaguchi ordered the 31st Division, which had retreated from Kohima when facing starvation, to join the 15th Division in a renewed attack on Imphal from the north. Neither division obeyed the order, being in no condition to comply. When he realised that none of his formations were obeying his orders to attack, Mutaguchi finally ordered the offensive to be broken off on 3 July. The Japanese, reduced in many cases to a rabble, fell back to the Chindwin river, abandoning their artillery, transport and many soldiers too badly wounded or sick to walk. The Allies recovered Tamu at the end of July, and discovered that it contained 550 unburied Japanese corpses and, among the dead, more than 100 more dying.

The Japanese defeat at Kohima and Imphal was the largest up until that time. They had suffered 54,879 casualties, including 13,376 killed as well as 920 casualties in the preliminary battles in Assam. Most of these losses were the result of starvation, disease and exhaustion.

The Allies suffered 12,603 casualties.

The Japanese had also lost almost every one of the 12,000 pack horses and mules in their transport units and the 30,000 cattle used either as beasts of burden or as rations, as well as many trucks and other vehicles. The loss of pack animals was to cripple several of their divisions during the following year. Mutaguchi had sacked all of his divisional commanders during the battle. Both he and Kawabe were themselves subsequently relieved of command.

In December, Slim and Scoones, Christison and Stopford, his three corps commanders, were knighted by the viceroy of India, Field Marshal the Lord Wavell, at a ceremony at Imphal in front of Scottish, Gurkha and Punjab regiments.

By the middle of 1944, the Allied air forces possessed undisputed air supremacy over Burma. The last major effort by the Imperial Japanese army air force had been over the Arakan in February and March, when it had suffered severe losses. During the Imphal and Kohima battles, it were able to make barely half a dozen significant raids.

The IV Corps enjoyed close air support from fighter-bombers and dive bombers of the RAF’s No. 221 Group. Allied fighter-bombers and medium bombers shot up and bombed Japanese concentrations, supply dumps, transport, roads and bridges all the way to the Chindwin river. The monsoon, which occurs every year from May to September, in no way diminished the RAF’s air activity. The RAF’s 3rd Tactical Air Force, under the command of Air Marshal J. E. A. Baldwin, increased its sortie rate to 24,000 during the worst four months of the monsoon, nearly six times the figure of the previous year’s record.

However, the most important contribution to the Allied victory was made by British and US transport aircraft. The Allies could fly men, equipment and supplies into the airstrips at Imphal (and Palel until the onset of the monsoon rains) so that, although cut off by land, the town was not without a lifeline. By the end of the battle, the Allied air forces had flown 19,000 tons of supplies and 12,000 men into Kohima and Imphal, and flown out 13,000 casualties and 43,000 non-combatants. Among the supplies carried during the siege were more than one million gallons of fuel, more than 1,000 bags of mail and 40 million cigarettes. Several thousand mules were used to supply outlying outposts: for example, to the Indian 17th Light Division up the Bishenpur trail, so animal fodder was also flown in during the siege. Allied aircraft could also parachute ammunition, rations, medical supplies and even drinking water to surrounded units.

At the start of the battle, the South-East Asia Command had available 76 transport aircraft, most of them Douglas C-47 Skytrain twin-engined machines, but many others were dedicated to supplying the Nationalist Chinese under Chiang Kai-Shek, or to establishing USAAF bomber bases in China, over 'The Hump'. Not even Mountbatten, the commander-in-chief, had the authority to commandeer any of these aircraft, but at the crisis of the battle in the middle of March he nevertheless did so, acquiring 20 Curtiss C-46 Commando twin-engined aircraft, in lift terms the equivalent of another 30 C-47 machines. Mountbatten was supported by US officers at SEAC and the headquarters of the US China-Burma-India Theater.