The 'Battle of Toungoo' was fought between Japanese and Chinese forces as one of the key battles in the 'Battle of Yunnan-Burma Road' in the Burma campaign, and Chinese failure to hold Toungoo opened the route for the Japanese to make their lunge to Lashio around the Allied flank and into the Chinese rear (19/29 March 1942).

On 8 March 1942, the day on which Rangoon fell to the Japanese, advanced elements of Major General Dai Anlan’s Chinese 200^th Division arrived in the Toungoo area, on the western bank of the Sitting river, and assumed control of the defence of this key location from a small detachment of British forces. Toungoo controlled the road to the north in the direction of Mandalay and the bridge over the Sittang river that carried the road to the east into the Karenni states and north to Loikaw, the Shan states, Lashio and the Chinese province of Yunnan. The loss of the town to the Japanese could threaten the flank of the Allied defensive line in Burma and open the way to a Japanese advance into central Burma.

Dai decided that Toungoo itself would be the main defensive position of the Chinese forces, with an outpost line to the south at Oktwin. He sent the Motorised Cavalry Regiment and 1^st Company of the 598^th Regiment to the banks of the Kan river, some 35 miles (56 km) to the south of Toungoo and 12 miles (20 km) to the south of Pyu. The cavalry regiment and the infantry company pushed forward to the Kan river, with a platoon of cyclists taking up position near the bridge at the village of Nyaungchidauk. The task of these small units was to delay the advance of the Japanese until the defences of Toungoo had been completed.

Meanwhile, the 200^th Division began digging in within the old city walls and at the advanced line at Oktwin. Toungoo itself was divided into the new town to the east of the railway and the old town to the west of it. The old town had a well preserved ditch and fortified wall which provided a good defensive position for the Chinese, who then enhanced the defences with carefully concealed positions built using the abundant local timber. To make things more difficult for the attackers, the land around Toungoo was flat and featureless, except for the Sittang river to the east.

Some 10 days later, on 18 March, the first skirmish with the leading elements of Lieutenant General Hiroshi Takeuchi’s 55^th Division, of Lieutenant General Shojiro Iida’s 15^th Army, began on the Kan river at Nyaungchidauk. Falling back over the next three days, the Chinese cavalry regiment delayed the Japanese advance while the Chinese completed their defences at Oktwin and Toungoo. When the Japanese attacked Oktwin they were held for another two days by determined Chinese resistance.

On 24 March, the 55^th Division's 12^th Regiment made frontal assaults on the Oktwin positions. The same division’s 143^rd Regiment, with the aid of friendly local Burmese, used the cover of the jungle and wooded area to the west of the town to advance 3.7 miles (6 km) to the north and attack Toungoo airfield and a nearby railway station. It was defended only by an engineer battalion, whose commander withdrew in a panic. This cut the 200^th Division's communications to the north, and left it encircled on three sides.

Dai abandoned the outlying positions to concentrate his defence near the city walls of Toungoo. The 598^th Regiment held the northern part of the Toungoo defences, the 599^th Regiment the south of the city and the 600^th Regiment the west. The divisional headquarters moved from the town to the eastern bank of the Sittang river to avoid Japanese air and artillery attacks, and also to safeguard the remaining supply route to the east. Part of a Replacement Regiment, which had arrived in the course of the previous day, was posted on the eastern bank of the Sittang river to extend the Chinese positions to cover the supply line as well as the divisional headquarters.

At 08.00 on 25 March, the Japanese launched an all-out attack against all three sides of Toungoo with the 143^rd Regiment on the left, the 112^th Regiment on the right and the 55^th Cavalry Regiment and one company of infantry along the Sittang river. The Japanese plan was to compress the Chinese forces against the Sittang river, where they would be annihilated. Despite local penetrations in the north-western part of the defensive perimeter, strong Chinese resistance prevented the Japanese making major progress until 22.00, when Japanese troops infiltrated Chinese positions in the north-western part of the Toungoo citadel, soon followed by a full battalion.

The Chinese reinforced the 600^th Regiment with the 2/598^th Regiment and counterattacked. There was severe house-to-house fighting and the lines between the forces were so close that the Japanese air and artillery support found it difficult to avoid hitting its own men. The counterattack failed to recover the lost positions when Japanese troops made good use of the buildings and the stone walls around a local cemetery. The 600^th Regiment was then moved back between the other two regiments to defend Toungoo itself. Elsewhere the bridge over Sittang river became the target for Japanese firepower and was so severely damaged that vehicles could not cross it.

Japanese attacks continued on 26 March. The 112^th Regiment attacked and took the south-western corner of Toungoo but was unable to make any further progress. On the left, a flanking move to attack the north-western part of Toungoo was no more successful. The 55^th Cavalry Regiment's attack was also repulsed. The Chinese launched counterattacks against the 112^th Regiment and the 55^th Cavalry Regiment with about 300 troops in each sector. These counterattacks were defeated, but losses were heavy and offensive strength declined.

By the evening, the Japanese had taken the western part of Toungoo to the west of the railway, while the Chinese troops held the main part of the city to he east of the railway. Both sides faced each other across the railway at a distance of less than 110 yards (100 m), making it difficult for Japanese air and artillery support. Eventually the Japanese withdrew some 220 yards (200 m) to allow their warplanes and guns to operate more effectively. During the bombardment, the Chinese hid in their camouflaged positions then held their fire until the Japanese advanced and were within 45 and 55 yards (40 to 50 m), and then opened on them with machine guns and grenades. This happened repeatedly, and by the end of the day the 200^th Division had very heavy casualties but the Japanese also suffered heavily and were finding it hard to continue their frontal attacks. The arrival of Major General Liao Yaoxiang’s New 22^nd Division to the north of Yedashe forced the Japanese to send the 2/143^rd Regiment to Nangyuen as a blocking force to stop the Chinese reinforcement from reaching Toungoo, but while necessary, this greatly reduced the Japanese attacking strength. The third of the 55^th Division's major elements, the 144^th Regiment, as well as a battalion of artillery and a company of cavalry were not with the division in the 'Battle of Toungoo', so the division lacked sufficient manpower and the attack therefore stalled.

On 27 March, there was a pause in the morning, but during the afternoon Japanese warplanes systematically bombed and strafed the Chinese positions. The Japanese continued to press their attacks with advantage provided by this air support, and in the same afternoon fired large numbers of tear gas shells into the Chinese defences. Despite this, the Chinese held their ground, and the Japanese then decided to await the arrival of the 3^rd Heavy Field Artillery Regiment with its 150-mm (5.91-in) howitzers before attacking the Chinese positions once more on 28 March; the renewed assault was to be supported by air attacks.

On 28 March, the 3^rd Heavy Field Artillery Regiment arrived, and with strong support from bombers and more gas attacks inflicted heavy casualties on the Chinese. Benefiting from strong artillery support, the right wing of the attack managed to destroy many Chinese strongpoints. However, the Japanese light bombers did not arrive until 15.00 as they had been heavy fog at their airfields, and it was not possible to overcome the Chinese forces' stubborn resistance as this was deployed in depth, even though the fighting lasted into the evening.

Meanwhile, the 56^th Reconnaissance Regiment of Lieutenant General Masao Watanabe’s 56^th Division, comprising of two motorised infantry companies and one machine gun company, one field artillery company of 75-mm (2.95-in) mountain guns, and one platoon of engineers, was moving rapidly to the north from Rangoon in a column of 45 trucks, with a company of six armored cars and a total of some 404 men. This force made rapid progress along the main road to Toungoo and had reached the 55^th Division's headquarters by 12.00 on 28 March. It was decided to move this force to the east of the Sittang river for an attack on the rear of the Chinese positions. Crossing at 20.00 the same day, the Japanese force forded the Sittang river at Wagyi, just to the south of Toungoo, where the water was only chest high, leaving behind its vehicles.

If the Japanese attack to the east of the Sittang river was successful, the 200^th Division would be entirely encircled. The divisional commander personally organised the defence, and two companies of the 3/598^th Regiment were ordered to attack the exposed Japanese left flank. A intense fight continued within Toungoo. Around the divisional headquarters on the eastern bank, the fighting inflicted heavy casualties on the 3/599^th Regiment as well as the divisional support company, but even so the Chinese were able to hold their ground.

On 29 March, the 55^th Division used its last strength to attack once more with the support of all available guns. By 12.00, the Japanese troops on the left were able to advance into the north-western part of Toungoo, and the Chinese line of retreat was thereby threatened. Covered by the fight to the west, the 56^th Reconnaissance Regiment moved to the north and attacked the Chinese flank guard to the east of the river and by 12.00 on 29 March had overrun it, threatening the divisional headquarters and the Sittang river bridge.

During the afternoon of 29 March, orders were received for the entire 200^th Division to withdraw that evening initially toward the east, and then to the north along the eastern bank of the Sittang river. Fighting in Toungoo itself continued into the dark with the town on fire. The Chinese continued to resist stubbornly and no progress was made by the Japanese. By 22.00 on 29 March, the motorised 56^th Reconnaissance Regiment had closed on the bridge over the Sittang river and at as darkness fell noted signs of wavering in the Chinese ranks. This was in fact the Chinese withdrawal. Dai had each Chinese battalion leave a rearguard which launched night attacks to cover the withdrawal of the main force. The retreat was led by the 599^th Regiment crossing the battered and threatened bridge, followed by the 600^th Regiment and then the 598^th Regiment, which forded the river. By 04.00 the entire 200^th Division had moved out of Toungoo in good order, taking all its wounded. The Chinese claimed that their rearguards left before dawn.

On the morning of 30 March, the 55^th Division attacked all along the front, claiming heavy resistance despite withdrawal of most, if not all, of the Chinese. After engineers managed to blow the Chinese positions and strongpoints at 08.50, men of the 55^th Division finally broke through and linked with the troops of the 56^th Division which had seized the vital bridge over the Sittang river at 07.00 and then attacked Toungoo from the east. This ended the battle, leaving the Japanese in possession of Toungoo and bridge over the Sittang river. The road to the east was open for the use of the Japanese to outflank the Allied line in Burma.

The New 22^nd Division, which had been sent to the south to support the 200^th Division, had meanwhile advanced as far as Nangyun railway station, and partially dislodged the 2/143^rd Regiment from its position there. The New 22^nd Division also sent patrols farther to the south in the direction of Toungoo,thus threatening the Japanese flank and rear. The retreating 200^th Division joined the New 22^nd Division at Yedashe after withdrawing northward on the river’s eastern bank from Toungoo, crossing the Sittang river to the east of Nangyun. The Chinese later withdrew to a new defensive positions at Yedashe in order to continue the blocking of the Japanese advance up the Sittang river valley.