On 15 May, a week after the Japanese occupied Rangoon, the 55th Division continued its advance towards Tonggu. The British, on the other hand, were retreating in the direction of India in full force. On the 17th, the vanguard search unit of the 55th Division of the Japanese Army, a cavalry squadron and an infantry squadron, was searching and advancing along the road from Yangon to Tonggu, and discovered the forward position of the squadron in Ekchun.

The Japanese search force immediately summoned the 112th Wing to attack this position of the squadron with the cooperation of the aircraft. The Battle of Burma of the Chinese Expeditionary Force began with the bombing of the Ekechun position by Japanese aircraft. Guarding the Ekechun position in front of Tonggu was the 568th Regiment of the 277th Brigade of the 93rd Division, and the 568th Regiment had seven days to prepare here, so the position was repaired quite well.

The 277th Brigade is also a unit that has been fighting defensive warfare for many years, and it has enough time to repair its positions in a clear and hierarchical manner, complete fortifications, a reasonable distribution of light and heavy machine-gun firing points, and defensive facilities such as anti-artillery holes, zigzag trenches, and steel wire fences. The 55th Division of the Japanese Army has never fought with the squadron, and since the attack on East and West Asia, it has been smooth sailing and extremely arrogant.

Although the ground was filled with gunsmoke and fire, only some fortifications were damaged, and the soldiers hid in the anti-artillery holes and suffered no casualties. After the plane flew away, several 92 infantry guns and more than 10 mortars set up by the 112th Wing began to cover the shelling. At the same time, an infantry squadron also began to attack.

The 1st Battalion of the 568th Regiment was guarding the first line of defense, and the soldiers who had experienced the saturation bombardment of Japanese aircraft, heavy artillery, and wing artillery did not take these small Japanese guns seriously at all, and entered the position under the Japanese artillery fire. Feng Lisan, the commander of the first battalion, saw that the Japanese army had only come up with an infantry squadron of more than 300 people, so he gave an order to go down, and only two heavy machine guns and three light machine guns were needed.

The Japanese infantry advanced to the barbed wire fence one hundred and fifty meters in front of the position, and could only slow down. Although the barbed wire fence had been damaged a lot, it must still be there in a mess, and the spikes on it would hurt as if they were piercing the flesh. The Japanese army slowed down, and the commander of the first battalion seized the opportunity, and with an order, several light and heavy machine guns were fired at the same time, and the crossfire caused the Japanese troops in front of the barbed wire to fall.

The Japanese artillery fire immediately turned to the machine gun fire point on the position, but the heavy machine gun was placed in the bunker fortification, and the thick tree trunk was the top of the bunker fortification, and the small Japanese cannon could not be moved. The light machine gun was used to constantly shift positions to prevent Japanese shelling. In addition to machine guns, the soldiers also had a lot of assault machines in their hands, and at a distance of 150 meters, the veterans of the 93rd Division could fight wherever they wanted.

When submachine guns and semi-automatic rifles also joined the ranks of shooting, the Japanese infantry squadron lost nearly half of its strength and had to retreat. The Japanese wing commander jumped in anger and immediately sent an infantry brigade to attack again. The commander of the 1st battalion opened fire this time and used 12 82 mortars of the heavy fire company to strike at the Japanese artillery positions.

The Japanese were unprepared, and all at once the artillery positions were attacked, and all the artillery was destroyed. Without artillery cover, the Japanese did not know how to attack at all, and the wing commander could only let the soldiers charge forcibly. In one day, this Japanese wing attacked a regiment of positions six times, leaving behind hundreds of corpses, and failed to break through even the first line of defense.

When the 93rd Division exchanged fire with the Japanese army, Wang Haitao had already reached Mandalay and set up the front headquarters of the First Route Army. After General Stilwell arrived in Mandalay, he analyzed the strength and current pattern of the two sides, proposed the Battle of Tonggu, and asked Wang Haitao to throw all three divisions of the 90th Army into the Tonggu battlefield, and after withstanding the Japanese attack, he would look for fighters to counterattack Yangon.

Wang Haitao knew that here in Yangon, the Japanese army would soon concentrate four divisions and regiments, more than 100,000 troops, and with the help of airplanes, its strength should not be underestimated. And the British army retreated all the way to Ringanqiang, although there were still 40,000 troops, but there was no hope at all. Behind him, the Fifth Army only reached Lashio, and the 66th Army was still on the Sino-Burmese border.

The 90th Army pressed the whole army to the Tonggu line, and if the Fifth Army did not arrive at Mandalay, after the Japanese army divided its troops to fight Mandalay, it would encircle the 90th Army in the Tonggu area, even if the 90th Army could not be afraid of the four divisions of the Japanese army, but Wang Haitao would not fight such a hard battle. Wang Haitao still hoped to use the 93rd Division to withstand the Japanese army for a while longer, so that he could calmly arrange himself in the Mandalay area, and then conduct a prepared battle in Mandalay, striving to eat up one or two divisions of the Japanese army.

Wang Haitao's opinion made General Stilwell, who had been thinking about attacking, disagree, and both sides insisted on their own opinions. In the end, Wang Haitao made a concession and let the 90th Division go to Tonggu to support the 93rd Division, while the 210th Division held on to Mandalay. At the same time, the Fifth Army was ordered to guard Taunggyi with one division, and one division to meet between Taunggyi and Lashio, and the last division rushed to the east of Mandalay to stand by. The 66th Army was stationed in the Lashio area to prevent the Japanese army from outflanking and cutting off the Yunnan-Burma Highway and cutting off the retreat route of the First Army.

The 200th Division of General Dai Anlan of the Fifth Army was stationed in Taunggyi, and the 96th Division of General Yu Shao was stationed at Laika and Menggong on Taunggyi, ready to support the 200th Division at any time. Commander Du Yuming and General Liao Yaoxiang's newly formed 22nd Division rushed to the east of Mandalay to garrison Meimi. However, for various reasons, the new 22nd and 200th Divisions would not arrive until a week later, and the 96th Division would not be in position until 10 days later.

Wang Haitao sat in Mandalay and commanded the deployment of three armies, and the 93rd Division fought more and more fiercely every day. After the 112th Wing of the Japanese army was frustrated in the attack on the first day, it immediately appealed to the division headquarters for help. The next day, the commander of the 55th Division, Lieutenant General Takeuchi Kan, sent the 55th Mountain Artillery Wing, the 143rd Infantry Wing to support the 112th Wing, and two flying teams for air support.

When the Japanese 55th Mountain Artillery Wing arrived at the front line, it immediately laid down artillery positions and bombed the positions of the 568th Regiment together with 12 bombers of the same flying group. The 568th Regiment did not have special anti-aircraft weapons, and in the face of the bombing by Japanese planes, it could only use covert methods to evade it.

As soon as the Japanese planes left, Li Chunshan, commander of the 568th Regiment, did not allow the Japanese mountain artillery wing to bomb the position like this. Li Chunshan directly ordered a counterattack to the field artillery battalion. Tang Weiren, the commander of the field artillery battalion, had already prepared the eighteen 75 field guns, and as soon as the regiment commander's order arrived, the eighteen field guns lost their camouflage, and at the same time aimed at the Japanese artillery positions for counterattack.

In the battle, the Japanese army knew that the squadron on the opposite side had a certain number of mortars, but the mortars could not be compared with the artillery in terms of power and range. The 55th Mountain Artillery Wing set up its artillery position outside the maximum range of mortars, just to prevent the squadron from counterattacking with mortars. But I never expected that the squadron also had artillery of the same caliber.

The 568th Regiment's round of artillery return fire was accurate and fierce, and the Japanese artillery positions fell into confusion at once. After all, the 55th Division is only a newly formed Type B Division, and the elite level of the soldiers is far from being comparable to those old Type A divisions. By the time the commander of the mountain artillery wing stabilized the soldiers and prepared to return fire, the entire artillery position was already in a sea of fire, and the detonated shells flew everywhere, causing heavy casualties to the soldiers.

Seeing this, the commander had no choice but to retreat first, but dozens of mountain guns and a large number of shells were destroyed in this shelling. Without the artillery support of the artillery wing, these two wings of the 55th Division could only attack desperately with the lives of the soldiers under the cover of aircraft and battery guns.

The two wings of the Japanese army together numbered more than 7,000 people, and the planes kept bombing. After holding out for five days, the casualties of the 568th Regiment had reached half, and at this time the 93rd Division's defensive line in Tonggu had been completed, and Li Yuanhong saw that the 568th Regiment had completed the task of blocking it, so he ordered the 568th Regiment to withdraw to Tonggu City for repairs.

After the Japanese occupied the front position of Okchun, the entire 55th Division pressed towards the ancient city of Tong, leaving only the engineer units and baggage troops in Yangon. The commander of the 55th Division, Lieutenant General Takeuchi Kan, never expected that they had defeated only one regiment with great effort, and that there was another well-prepared division waiting for them in Tonggu City.

When the three wings of the 55th Division of the Japanese Army attacked Tonggucheng, they first occupied the Yongkegang airfield abandoned by the 93rd Division, and then surrounded Tonggucheng from three directions: south, north, and west. Upward in the north of the city, an infantry brigade and a cavalry squadron sent by the Japanese army attacked the Nanyang Railway Station, but the head was broken and bleeding under the counterattack of the 569th Regiment, and after most of the casualties, the remnants of the soldiers retreated.

On the frontal battlefield to the south, the 55th Division concentrated the strength of two wings and carried out a strong attack on the positions of the 571st and 572nd regiments of the 278th Brigade outside the city. If it weren't for the large number of Japanese aircraft, these two regiments would have been able to wipe out most of the Japanese army with artillery fire.

The last regiment rushed to the west, trying to attack Tonggu from the flank of Tonggu, and the 569th and 570th regiments of the 277th Brigade in Tonggu took advantage of the city wall and the mountains outside the city to ambush this wing, and almost completely annihilated this infantry wing. The Japanese army besieged Tonggu City for three days, not only failed to capture the outlying positions of Tonggu City, but also lost more than half of its troops, which made Lieutenant General Takeuchi Hiro, the commander of the division who had never fought with the squadron, extremely shocked.