The 'Battle of Pakokku' and the subsequent Irrawaddy river operations were a series of battles fought between the British and Japanese, and were instrumental in facilitating the eventual British capture of Rangoon in the summer of 1945 (4 February/13 May 1945).

The thrust of Lieutenant General Kotoku Sato’s Japanese 31^st Division toward Kohima in 'U' had been a costly failure, eventually forcing the division into a disastrous retreat. Lieutenant General Genzo Yanagida’s Japanese 33^rd Division, Lieutenant General Masafumi Yamauchi’s Japanese 15^th Division and Shah Nawaz Khan’s 1^st Division of Subhas Chandra Bose’s collaborationist Indian National Army had suffered a similar fate at Imphal in a campaign which cost Lieutenant General Renya Mutaguchi’s Japanese 15^th Army and its allies at least 50,000 men dead. In previous years there had been a lull in fighting during the monsoon period, but this was not to be the case in 1944/45. Admiral the Lord Louis Mountbatten’s South-East Asia Command and the command of the British forces in India decided that it was time to target the heart of Lieutenant General Heitaro Kimura’s Burma Area Army, and the resulting plan by Lieutenant General Sir William Slim’s 14^th Army paved the way for continued combat through the monsoon months as a pursuit of the defeated Japanese in Kohima and plains of Imphal. Within this British advance, Major General G. C. Evans’s (later Major General C. G. Nicholson’s, Major General D. F. W. Warren’s and Major General E. C. R. Mansergh’s) Indian 5^th Division down the Tiddim Road and Major General C. C. Fowkes’s (later Mansergh;s and Major General W. A. Dimoline’s 11^th (East Africa) Division down the Kabaw valley, until the two met at Kalemyo. The next offensive plan centred on the occupation of central Burma, as far to the south as Mandalay, to exploit still farther to the south and destroy the Japanese forces in the Shwebo plains to the north of the Irrawaddy river, where armour could be used effectively. Allied forces crossed the Chindwin river and the spearheads of the 14^th Army’s two corps, which were Lieutenant General Sir Geoffrey Scoones’s (later Lieutenant General Sir Frank Messervy’s) Indian IV Corps and Lieutenant General Sir Montagu Stopford’s Indian XXXIII Corps, were moving into selected battle areas, which took the Japanese by surprise as they had not anticipated any major operations during the monsoon period. The 14^th Army was now faced with a major obstacle, in the form of the Irrawaddy river, covered by determined Japanese forces. In the middle of its southward run to the sea, the Irrawaddy river is about 2,000 yards (1830 m) wide and dotted with treacherous and shifting sand bars. Any direct crossing, if opposed, would have cost heavy casualties and possessed only a low chance of success.

The new situation demanded a revised plan to ensure that surprise was gained to allow the 14^th Army to cross this might river barrier and emerge to fight major battles in the plains around Mandalay and in the low hills of Meiktila. Since there was not enough equipment to make a single major but opposed river crossing, Slim planned more than one crossing shielded by deception plans to conceal the point of the real assault in strength. It was decided to make a crossing to the north of Mandalay in sufficient strength to draw the Japanese main forces, while the main crossing was made farther to the south of the Japanese concentrations below Mandalay. The revised plan was for Messervy’s Indian IV Corps less Major General T. W. Rees’s Indian 19^th Division (Major General D. T. Cowan’s Indian 7^th Division, Major General D. T. Cowan’s Indian 17^th Infantry Division, Brigadier T. H. S. Galletly’s 28^th East African Brigade, Brigadier P. C. Marandin’s Lushai Brigade and Brigadier C. E. Pert’s Indian 255^th Tank Brigade) to move due south down the Gangaw valley for nearly 300 miles (485 km), seize a bridgehead across the Irrawaddy river just to the south-west of at Pakokku and then strike, with supplies delivered by air, to the south-east with mechanised forces toward Meiktila and Thazi.

The next operation across the Irrawaddy river was to be a magnificent stroke, characterised by both courage and deception, that was to make possible the destruction of the Japanese army in Burma. This involved advance through the Gangaw valley followed by a crossing of the Irrawaddy river to seize a bridgehead at Nyaung U. Thereafter a quick thrust would be made toward Meiktila, whose capture would cut off the Japanese fighting in the northern and central Burma. The operation of the Indian 7^th Division was begun by Brigadier H. W. Dinwiddie’s Indian 114^th Brigade, which moved to Tamu, constructing a stretch of 180 miles (290 km) of motorable road from Tamu to Gangaw in 15 days. The Indian 114^th Brigade and divisional headquarters moved along the main axis, which was the Kaley valley road. The advance was to begin on 19 January and the tasks of the Indian 7^th Divisional tasks were firstly, to advance and seize the Pauk area up to and including crossing of Yaw Chaung by a date no later than 1 February; and secondly, to seize a bridgehead over the Irrawaddy river in the area between Chauk and Pakokku suitable for advance to Meiktila by a date no later than 15 February.

By this period of the Burma campaign, therefore, the Japanese had been defeated in the 'Battle of Kohima' and 'Battle of Imphal', and the offensive to destroy all Japanese forces in the area to the north of the Irrawaddy river had been schemed on the basis of a surprise crossing of the river. The Indian 7^th Division and other formations and units were to seize a bridgehead across the Irrawaddy river to the south-west of at Pakokku by 15 February and move to the south-east with mechanised forces. The operations of the Indian 7^th Division were initiated by the Indian 114^th Brigade, which was led by the 4/5^th Royal Gurkha Rifles (Frontier Force). The battalion departed Merema on 4 December, reached its assembly area on 3 February and closed on the launch point for the crossing near Pakokku on 5 February after C Company had cleared the road. The Japanese shelled the troops from their positions in Kahnla, a village on the southern bank of the Irrawaddy river.

On 5 February, three companies of Lieutenant Colonel J. H. Turner’s 4/5^th Royal Gurkha Rifles made an encircling move on the village of Kahnla. One company moved farther to the left and attacked from the north-east after coming under intense Japanese attack, while a second company formed in Kahnla village for the attack from the west. From 17.30, the Gurkhas fought their way through and overran half of the Japanese position, including a strong bunker armed with medium machine guns. At least 30 Japanese were killed and many more wounded, and two medium and three light machine guns, as well as 20 rifles were taken.

Reconnaissance on 6 February indicated that the remainder of the objective was strongly held by the Japanese and on 7 February the 4/1^st Gurkha Rifles of Brigadier R. G. Collingwood’s Indian 33^rd Brigade established a firm base for the 4/5^th Royal Gurkha Rifles.On 8 February, one company cleared another Japanese position, killing 12 and wounding three Japanese. The main attack, which had been planned for early morning hours of 10 February, was pressed without any air support as a result of bad weather. The attack began with one company moving forward with support from tanks of the Indian 255^th Tank Brigade (Gordon Highlanders). By the afternoon, they had captured their objective. The 4/5^th Royal Gurkha Rifles suffered a significant loss during the battle when its commanding officer was killed. Resistance by the Japanese position was fanatical: only one prisoner was taken and 51 bodies were counted. During the night of 10/11 February, the Japanese launched six unsuccessful counterattacks and on the night of 11/12 February 1945 attempted to infiltrate into the 4/5^th Royal Gurkha Rifles' position, but were unsuccessful. On the night of 12/13 February, men of the 4/5^th Royal Gurkha Rifles occupied positions closer to Pakokku in the village of Sinlan, then moved to search and occupy Pakokku itself. The operation had effectively destroyed the equivalent of one Japanese battalion, and the first stage of the Indian 7^th Division’s task had been completed and foothold gained on the western bank of the Irrawaddy river as the starting point for further operations in the next phase of the offensive to destroy the Japanese forces in Burma.

After the Indian 7^th Division had captured Pakokku on 14 February, other Allied forces (Major General D. D. Gracey’s Indian 20^th Division and Major General C. G. G. Nicholson’s British 2^nd Division) of Stopford’s Indian XXXIII Corps made another crossing of the Irrawaddy river farther to the north-east at Nyaung U, to the north of ancient Burmese capital of Pagan. The Indian 20^th Division’s crossing was made on a wide front. Both the main attack at Nyaung U and a secondary crossing at Pagan were initially disastrous. Pagan and Nyaung U were defended by two battalions of the Indian National Army's 4^th Guerrilla Regiment, with a third battalion in reserve. The Indian 20^th Division suffered heavy losses as its assault boats broke down under the fire of machine gun sweeping the river. Eventually, support from tanks of the Gordon Highlanders firing across the river and concentrated artillery bombardment forced the defenders at Nyaung U to surrender. At Pagan, the defending troops, the Indian National Army's 9^th Battalion, took a heavy toll of the 1/11^th Sikh Regiment before withdrawing to Mt Popa.

By 20 February, most of the British-led forces had crossed the river and captured Meiktila, as planned. The capture of Pakokku by the 4/5^th Royal Gurkha Rifles opened the way for further operations by the Indian 7^th Division. On 19 February, the 4/5^th Royal Gurkha Rifles cleared an island, 5 miles (8 km) long and 3 miles (4.8 km) wide, in the Irrawaddy river off Pakokku, which was interfering with forward movement.

On 24 February, the Gurkhas moved to the south of Pakokku, crossed the Irrawaddy river and took over part of Nyaung U bridgehead. On 25 February, a squadron of the 116^th Regiment Royal Armoured Corps (Gordon Highlanders), part of the Indian 255^th Tank Brigade, supported the assault of the battalion and the village was soon secured; seven Japanese, including one officer, were killed. Throughout the month of April, the Allies continued to engage the Japanese in the area and this led to the capture of Letse and Seikpyu. On the morning of 24 April, the leading troops were pinned by heavy fire from a ridge with a prominent golden pagoda and a monastery. The objective was captured by a company of the 4/5^th Royal Gurkha Rifles supported by a heavy artillery concentration, and 39 Japanese bodies were found. By 30 April, the 4/5^th Royal Gurkha Rifles had secured Pwinbu and then moved to clear the Japanese position at Pagan village. Between 5 and 8 May concerted assaults were launched on Japanese positions which formed a ring around the position from the south: on 6 May the Gurkhas established a roadblock in the rear of the Japanese and on 7 May launched an assault was launched on Pagan village that was taken one day later.

While these subsidiary operations, relatively minor in comparison, had been taking place to the west of the Irrawaddy river, the 'Battle of Mandalay' had been fought and inflicted on the Japanese decisive defeat. With the exception of those forces to the east of the Sittang river, the Burma Area Army thus ceased to exist as an organised and integrated force. The British-led forces advanced down the Irrawaddy and Sittang river, and on 3 May reoccupied Rangoon, Burma’s main city, bringing Slim’s plan to a triumphant conclusion. The monsoon was about to break and the next phase of the Burmas campaign was to be a large-scale mopping up operation of the forces to the east of the Sittang river. On 14 May, the 4/5^th Royal Gurkha Rifles departed Pagan for what it hoped would be a fairly permanent monsoon location, but after several changes of location it arrived at Allanmyo, some 40 miles (65 km) to the north of Prome on the Irrawaddy river.