'Ha' was a Japanese limited offensive in the Arakan western coastal region of Burma designed to draw into this area British reserves which would thus be unavailable to reinforce the effort father to the north against 'U', and could then be destroyed together with the rest of Lieutenant General A. F. P. Christison’s Indian XV Corps of Lieutenant General W. J. Slim’s 14^th Army (3/24 February 1944).

Otherwise known as the Battle of the Ngakyedauk Pass or Battle of Sinzweya, and more popularly as the Battle of the 'Admin Box', 'Ha' initially pitted one Japanese division against a British-led force of two infantry divisions and one armoured regiment, later reinforced by another two infantry divisions. The strategic object was thus to divert the 14^th Army’s attention and forces before the start of 'U' against Imphal and north-eastern India by Lieutenant General Renya Mutaguchi’s 15^th Army.

From late 1941 into early 1942 the Japanese had driven a diversity of British, Indian and Chinese troops out of Burma into north-eastern India and southern China. There was no major fighting in the middle part of 1942 as each side rebuilt its strength for the campaigns to come, and on 21 September 1942 operations began once more after Field Marshal Sir Archibald Wavell, commanding the British forces in India, had decided that small-scale operations should be undertaken to boost morale and gain experience pending the possibility of major operations late in 1943 or early in 1944. The location Wavell selected for this initial effort was the Arakan western coastal region, where operations could be nourished by sea, supported in the air from bases in south-east India, and perhaps gain the areas which would be required as the staging points and for the establishment of the air bases which would be needed for the eventual reconquest of southern Burma and the recapture of Rangoon.

The first British offensive into the Arakan region was 'Cannibal', launched on 22 December 1942 after Major General W. L. Lloyd’s Indian 14^th Division had started to advance to the south from Chittagong via Cox’s Bazar into the northern part of Arakan on 21 September with the object of taking Akyab island off the end of the Mayu peninsula. The island possessed an important airfield, from which the Imperial Japanese army air force had launched raids on Calcutta and other Indian cities, and which also featured prominently in Allied plans to recapture Burma. 'Cannibal' was a disastrous failure. As the Indian army was in the process of a huge and wholly volunteer expansion, most of the Indian and British units committed to the offensive lacked both adequate training and operational experience. Key aspects of 'Cannibal', as later realised and digested, were that exhausted units had been left in the front line, resulting in a severe deterioration of their morale, tactics and equipment were not suited to operations in the jungle-covered hills of the area, Japanese units repeatedly achieved tactical and operational surprise by crossing rivers and hills which the Allies had dismissed as impassable, and the British command structure was inefficient as reflected in 'Cannibal' by the use of just one and therefore radically overworked divisional headquarters to control a large number of brigades and also a major lines-of-communications area.

With these factors appreciated, during the following months the British reorganised, undertook extensive jungle training, and prepared their forces for a renewed effort in 1944. Under the command of Lieutenant General W. J. Slim’s British 14^th Army, this 'Cudgel', or second Arakan offensive, was to be launched by Lieutenant General A. F. P. Christison’s Indian XV Corps.

Lying between the Bay of Bengal to its west and the long estuary of the Kalapanzin river to its each, the Mayu peninsula comprises a coastal plain, indented by several chaungs (tidal creeks), and separated from the fertile valley of the Kalapanzin river by the jungle-covered Mayu hill range. Major General H. R. Briggs’s Indian 5^th Division, which had already experienced heavy fighting in East Africa and the Western Desert, attacked down the coastal plain from Bawli Bazar to Waybin with brigades disposed as far forward as Maungdaw, which was taken on 9 January. Major General F. W. Messervy’s well-trained but comparatively inexperienced Indian 7^th Division attacked down the Kalapanzin river valley from Goppe Bazar and Taung Bazar to Awlanbyin with brigades as far forward as Buthidaung. Major General C. G. Woolner’s British 81^st (West Africa) Division advanced farther to the east down the Kaladan river valley, largely to shield the left flank of the Indian 7^th Division, but would not directly affect the battle. Two other formations, Major General C. E. N. Lomax’s Indian 26^th Division and Major General F. W. Festing’s British 36^th Division, were in reserve at Chittagong and Calcutta respectively.

The advance was initially cautiously but then developed a steady momentum. On 9 January 1944 the Indian 5^th Division took the small port of Maungdaw on the western side of the Nef estuary, and while the division reduced Japanese positions to the south of the port (the village of Razabil and a hill known from its shape as the 'Tortoise'), the Indian XV Corps readied itself for the next stage of its advance to the south, which was to take part of the Mayu hill range, where two disused railway tunnels provided a route through the hills linking Maungdaw to the towns of Buthidaung and Letwedet in the Kalapanzin river valley. To allow the redeployment of troops and the delivery of supplies for this attack, the engineers of the Indian 7^th Division improved a narrow track, known as the Ngakyedauk pass, across the hills between Wabyin and Kwazon, and a large administration area, later known as the 'Admin Box' at Sinzweya near the eastern end of the pass.

Lieutenant General Shozo Sakurai’s 28^th Army was the Japanese formation responsible for the defence of Arakan and southern Burma, and it was Lieutenant General Tadashi Hanaya’s 55^th Division which held Arakan. Most of the division’s strength (five infantry battalions) was grouped as the 'Sakurai' Column in the Mayu area under the command of its infantry group headquarters led by Major General Tokutaro Sakurai. The Japanese were confident that they could repeat their defeat of 'Cannibal' in the preceding year by means of a cleverly constructed local counterattack, and perhaps even advance to Chittagong, the port on which Indian XV Corps relied for its supplies. The Japanese also believed that by launching their 'Ha' (otherwise 'Z') attack in the first week of February 1944, they would force the Allies to send reinforcements to Arakan from the central front in the Assamese area of north-eastern India, so aiding the main Japanese offensive, 'U' aimed initially at Imphal, to be launched by Mutaguchi’s 15^th Army during the first week of March.

Hanaya’s plan was simple, and relied on the particular military virtues of his men, who were used to operating at a numerical disadvantage, with poor communications and in difficult terrain: while Major General Sadashichi Doi’s 'Doi' Column pinned the Indian 5^th and 7^th Divisions with frontal attacks, the 'Tanahashi' Force and 'Kubo' Force of Major General Tokutaro Sakurai’s 'Sakurai' Column would depart from an assembly area at Dabrugyaung behind the Japanese right flank to penetrate the 'impassable' country between the Indian 7^th Division and the 81^st (West Africa) Division to reach Taung Bazar behind the left flank of the pinned Indian forces, and then fall on their rear. Beginning on 5 February, 'Sakurai' Column infiltrated the Indian 7^th Division’s front, which was widely dispersed, and moved north undetected to the small town of Taung Bazaar. Here the Japanese crossed the Kalapanzin river and swung to the west and south, in the process dividing into the 'Kubo' Force and two halves of the 'Tanahashi' Force: the former was the more northerly of these forces, and headed across the Mayu hill range to fall on the British line of communication just to the north of Chota Maunghnama, and the latter head to the south-west and south toward the Ngakyedauk pass road where, on 6 February, its attacked the headquarters of the Indian 7^th Division. There was heavy fighting before the Indian 7^th Division’s signallers and administration personnel destroyed their documents and equipment, divided into small parties and retreated to the 'Admin Box'.

The main part of the 'Sakurai' Column pursued toward Sinzweya and the rear of Indian 7^th Division even as the 1/213^rd Regiment (named 'Kubo' Force after its commanding officer) crossed the Mayu hill range at a seemingly impossible place and established ambushes on the coastal road by which the Indian 5^th Division was supplied. The Japanese still holding Razabil and the railway tunnels area was 'Doi' Column, which launched a series of subsidiary attacks from points between Razabil and Buthidaung to the north in order to link with the 'Sakurai' Column, and made smaller raids and diversions, while unexpectedly large numbers of Japanese fighter warplanes flew from the airfield on Akyab island to contest the skies over the battlefield.

It was clear to commanders at every level of the Indian XV Corps that the situation was serious. However, the 14^th Army devoted considerable effort to the creation of ways to counter the Japanese standard tactics of infiltration and encirclement. The forward divisions of the Indian XV Corps were now instructed to dig in and hold their positions rather than retreat, while the reserve divisions advanced to their relief.

The next, and indeed most obvious, Japanese objective was the administrative area at Sinzweya, defended by headquarters and line of communication troops together with the 25^th Light AA/Anti-Tank Regiment of the Royal Artillery. As Messervy was in the jungle and out of contact, Christison ordered Brigadier G. C. E. Evans, only recently appointed commander of the Indian 9^th Brigade in the Indian 5^th Division, to make his way to the 'Admin Box', assume command and hold the 'Admin Box'. Evans reinforced the defence with the 2/West Yorkshire Regiment of his own brigade, and the 24^th Mountain Artillery Regiment of the Indian army. However, the most vital reinforcement of all was two squadrons of M3 Lee medium tanks of the 25^th Dragoons. The defence was later supplemented by part of the 4/8^th Gurkha Rifles of Brigadier W. A. Crowther’s Indian 89^th Brigade of the Indian 7^th Division and also the artillery of the 8^th (Belfast) HAA Regiment 6^th Medium Regiment, both of the Royal Artillery.

Under Evans’s command, the 'Admin Box' was developed into a tight but well-defended area. The clearing was just under 1,200 yards (1100 m) in diameter, and within this area ammunition dumps were piled at the foot of the western face of a central hillock, the 150-ft (46-m) high 'Ammunition Hill'. When Messervy arrived at the 'Admin Box', followed by several officers of his headquarters staff who had made their way in small parties through Japanese forces, he was satisfied and therefore left the defence of the 'Admin Box' to Evans while he himself concentrated on re-establishing control over the rest of the division and supervising its effort.

Meanwhile, Douglas C-47 Dakota transport aircraft of the Allied air forces para-dropped ammunition and food to isolated troops, including the defenders of the 'Admin Box'. The air forces flew 714 sorties, in which they dropped 2,300 tons of supplies. This was a development which the Japanese had not anticipated, and meant that while they steadily ran short of supplies, the Indian formations could maintain their effort with full stomachs and ample ammunition. The Japanese tried to supply the 'Sakurai' Column with a convoy of pack mules and Arakanese porters, which followed the route of Sakurai’s infiltration, but this was ambushed and the supplies were seized.''''

The first para-drop missions were met by Japanese fighters, and some of the transport aircraft were forced to turn back, but then three squadrons of Supermarine Spitfire fighters, operating from new airfields in the Chittagong area, rapidly gained air superiority over the battlefield: the Spitfire fighters claimed to have shot down ore damaged 65 Japanese aircraft for the loss of three of their own number. However, the Japanese fighters shot down several Hawker Hurricane fighter-bombers and other aircraft. Whatever the exact numbers of aircraft lost, the Japanese fighters were quickly overwhelmed.

The ground fighting for the 'Admin Box' between 6 and 24 February was severe and generally of a close-quarter nature. During the night of 7/8 February, some Japanese troops captured the divisional main dressing station and murdered 35 medical staff and patients. When disseminated, the knowledge of this Japanese war crime almost certainly increased the resolve of defenders who now knew the sort of fate they might suffer were they to surrender. Japanese fire caused heavy casualties in the crowded defences and twice ignited ammunition dumps, but all Japanese efforts to overrun the defence were defeated by the tanks, to which the Japanese had no counter once their few pieces of mountain artillery had expended all their ammunition. The Japanese tried an all-out attack on the night of 14/15 February and took one hill on the perimeter, but with tank support the 2/West Yorkshire Regiment retook this position on the following day, although only at the cost of heavy casualties.

By 22 February the Japanese had been without food for several days. Tanahashi stated that his regiment had been reduced to 400 men out of an original strength of 2,150 and refused to make further attacks. On 24 February Tanahashi retreated without authorisation, and on 26 February Sakurai was forced to end 'Ha'. By this time the Indian 26^th Division had relieved the Indian 5^th Division, which sent a brigade to break through the Ngakyedauk pass to relieve Indian 7^th Division. The 'Kubo' Force was cut off and suffered heavy casualties as its sought to make its way back to the Japanese lines.

Although the Allied forces had suffered heavily, their wounded received prompt and effective medical treatment, whereas the Japanese had been forced to abandon many of their wounded to die. Some 5,000 Japanese dead were counted on the battlefield. Just as importantly for the Allies, though, was the fact that for the first time in the Burma campaign, the Japanese tactics had not just been countered but indeed turned against them. This was to be repeated on a far larger scale in the forthcoming Battle of Imphal. There was also a great fillip to Allied morale from the fact that British and Indian soldiers had held and defeated a major Japanese attack for the first time, and this success was widely broadcast.

The battle also demonstrated the value of Allied air power to supply and also to intervene over the land battlefield, and this became an increasingly significant factor in the final Allied victory in the Burma campaign.

In the second week of March, Brigadier D. F. W. Warren’s Indian 161^st Brigade, of the Indian 5^th Division, finally captured the 'Tortoise' and the other Japanese fortified positions around Razabil by a flanking manoeuvre, and the formation was then withdrawn into reserve. The Indian 26^th Division and British 36^th Division resumed the offensive late in March and early in April: the 36^th Division had taken the railway tunnels area by 4 April, and two days later men from the Indian 26^th Division captured the vital Point 551, a hill which dominated the area and where the Japanese had won an important victory just under a year earlier.

The Indian XV Corps' operations were now scaled back to make possible the diversio’n of transport aircraft and troops for the Battle of Imphal. As the torrential rains of the monsoon season began, it was found that the low-lying area around Buthidaung was malarial and unhealthy, and the Allies forces withdrew from the area to spare themselves losses to disease. With support from a unit of the Indian National Army and local Arakanese, the Japanese also undertook a counterattack in the Kaladan river valley, forcing the understrength and isolated 81^st (West Africa) Division to retreat.

Akyab remained in Japanese hands until January 1945, when the 'Talon' third Arakan campaign, in which an overland advance was supplemented by a number of outflanking amphibious assaults, finally expelled the Japanese from Arakan with heavy losses.

It is worth noting that the lightly armed 1/1^st Guerrilla Regiment of the anti-British Indian National Army had been directed to participate in 'Ha'. The battalion left Rangoon early in February, but by the time it arrived in Akyab at a time early in March, the Japanese offensive was nearing its end. The battalion subsequently marched up the Kaladan river and advanced slowly but successfully against West African units before crossing the Burma/India border to occupy Mowdok, near Chittagong.