Yang Sanwa, Li Laosi and others rushed into the woods on the shore, and there was another burst of grenades at the dense torches. Previously, when the Mongolian army smuggled across the river, they did not light the torches for fear of exposing the target. Now that the defenders had been alarmed, they simply turned the sneak attack into a strong attack, but when they climbed ashore, they found that there was no one. This situation was also expected by the Mongolian army, after all, according to the previous reconnaissance, there were only thirty people in this Thunderbolt army fortress. In the eyes of the Mongol army, as long as the river had been crossed, the fortress could be broken at the snap of a finger. The Mongolian army, which was full of thoughts about drinking and eating meat after breaking through the fortress, did not expect that the defenders not only did not cower in the fortress, but also rushed back. At that moment, these newly landed Mongol troops were about to march through the grove in the direction of the fortress, when they were caught off guard and ate another grenade, and retreated to the dry riverbed one after another.

The Thunderbolt army did not carry torches, and for a while the Mongolian army did not know how many people were in the woods on the riverbank, only that the other party was fierce, and the density of grenades thrown was much higher. Yang Sanwa and the others did not charge, but used muskets to shoot at the dense places of torches in the river. Seeing this, the Mongolian soldiers extinguished their torches one after another, and seeing the scattered gunfire, they knew that the Thunderbolts were not numerous, so they formed a group and began to charge, but as soon as they approached the riverbank, they were bombarded by a grenade that covered their heads, and they had to retreat to the dry place in the middle of the river. These Mongolian soldiers waited for the follow-up crossbowmen to arrive, trying to suppress the river bank with a dense rain of arrows, and then take the opportunity to cover and kill. As everyone knows, while they were waiting, reinforcements from the Thunderbolts also came. Several soldiers rushed from the fortress with them a weapon of mass destruction - mines.

The Mongol crossbowmen stood in the middle of the river, and there was a rain of arrows in the direction of the Thunderbolts—the flames fired from the muskets were so great that it was easy to identify. However, the Thunderbolts on the river embankment were sparsely numbered and crouched behind trees, and several rounds of arrows only made the Thunderbolts stop shooting with muskets, and did not hurt a single person. Seeing that there was no sound on the riverbank, the Mongolian army immediately sent a death squad to sneak towards the riverbank. The Mongol attack went well, with neither musket nor grenade fire. This made the soldiers of the Mongolian death squad secretly happy in their hearts, and when they praised the crossbowmen, a huge explosion sounded - an unlucky ghost stepped on a mine. The power of the mine was several times that of the grenade, and the Mongolian soldiers around the explosion site fell to the ground one after another. At this time, a dense number of grenades were dropped overhead. After a series of explosions, the Mongolian death squads left the wounded soldiers all over the ground and retreated in panic.

Seeing the heavy casualties in the hard rush, the Mongolian army switched to rockets fired at the groves on the riverbank. When the weather was dry, the thick dead branches and fallen leaves under the trees were ignited and spread rapidly. Yang Sanwa, Li Laosi and others saw that the situation was not good, so they retreated back to the fortress. The fire in the woods on the bank was blown by the mighty river wind, and for a time it turned into a prairie fire, and people could not be approached within tens of meters, and even detonated the mines planted under the river bank. Seeing that the fire was so large, the Mongolian commander knew that it was impossible to cross the river from here, so he ordered his men to move to the other side of the fort not far downstream. In the dry season, only three places in the vicinity of the river can be crossed, and the rest of the river is either turbulent or too deep. In addition to the burning place, the other is the section of the river directly opposite the fort, and the third is half a mile downstream of the fort. All three sections of the river were covered by artillery fire from the Perak forts.

At this time, it was already dark, and the Mongol army brigade was coming towards the fortress, and the Thunderbolt artillery fired. These guns had already set the parameters for firing, and under the salvo of shotguns, they knocked down a large number of Mongolian troops who were about to wade across the river in front of the fortress. Seeing this, the Mongol army tried to cross the river half a mile downstream, but the fate was even worse. Not only is the water chest-deep, but the current is also fast, and after a round of artillery, the water is full of dead and wounded of the Mongolian army, and the river is also dyed red.

When it was daylight, two cavalry teams came one after another. The Mongol cavalry were the first to reach the east bank, and they were supposed to break through directly into the hinterland of Hanzhou after the infantry had succeeded in their sneak attack on the fortress. Arriving at the fortress on the west bank was a cavalry company of the Perak Army that had arrived from Mianzhu, and ten miles behind them, a large number of lightly armed infantry were coming. Seeing this, the Mongolian commander knew that the sneak attack plan had failed. In desperation, he ordered the remaining men and horses to retreat beyond the range of the Perak artillery, began to cut down trees to build a camp, and waited for the arrival of the rear army. After these attacks, more than half of the 300 strikers he led have been damaged. This group of Mongolian troops was the new annex army of Yang Dayuan's department, with a total of 3,000 people, led by Yang Dayuan's nephew Yang Wen'an, who came to attack the Perak army at the request of Liu Heima.

After Liu Heima lost western Sichuan, Kublai Khan, who had always been enlightened, did not blame him, but let him continue to sit on Tongchuanfu Road. This Tongchuan road area is vast, under the jurisdiction of two governments, three armies and Kyushu, the population of more than one million, and in the central Sichuan region, the strategic location is very important. Kublai Khan did this not only to express his trust in Liu Heima, but also to win over other Han princes. Kublai Khan also painted cakes for Liu Heima, because most of the prefectures and counties of Tongchuanfu Road were still in the hands of the Southern Song Dynasty, and the pacification envoy of Tongchuanfu Road in the Southern Song Dynasty was Liu Quan, who was also in Luzhou. At present, in addition to Tongchuan Mansion, Suining Mansion, and Zizhou, there are also Jianzhou and Mianzhou on Chengdu Fu Road.

In terms of strength, Liu Quan's Luzhou Song army is obviously inferior to the Thunderbolt army. According to normal logic, it would have been easier for Liu Heima to attack Liu's entire Song army in the south than to attack the Thunderbolt army in the west, but Liu Heima's decision was carefully weighed. The Mongol army's meticulous work and spies were very powerful, and Liu Heima learned that the Perak army had rejected the order of the Lin'an court to send officials to Chengdu Prefecture and Penghan Prefecture, and even knew that Yu Xing had ordered the seizure of the Perak army caravan. From this, he concluded that if the Mongol army attacked the Song army in Luzhou, the Perak army would most likely send troops to help, and he would fall into a two-front combat situation at that time, and even repeat the footsteps of the new army attacking Jiading; As for the Mongol army attacking the Thunderbolt army, Liu Cheng will definitely stand still, whether it is out of order to preserve his strength or Yu Xing's order. What's more, the prefectures and counties of Tongchuan Fu Road are comparable to the rich West Sichuan Plain. Regaining the fertile land in western Sichuan can not only avenge an arrow, but also make grain and grass worry-free.

Liu Heima knew that in order to defeat the Thunderbolt army, he needed the right time, place and people. At present, the Thunderbolt Army has caused dissatisfaction in Lin'an, and it is even more at odds with the Sichuan Preparation Division. Under the pressure of Yu Xing, there will be no Song army in Sichuan to support the Thunderbolt army, this is the time of day; The location is also available. For the Mongolian soldiers and war horses who have lived in the bitter cold of the north for a long time, the temperature in western Sichuan is cool and comfortable in winter, and as long as they break through the defense line of the Perak army, the flat plain of western Sichuan is the world of the 3,000 cavalry they rebuilt. As for He, Kublai Khan had already issued an edict, asking Kudu and other Mongol generals to accept his moderation, and also ordered Yang Dayuan and other new annexed troops to send troops to help.

Liu Heima prepared an offensive against the Perak army after the beginning of autumn. Under Kublai Khan's strict orders, Yang Dayuan sent his most elite subordinates to battle, and Kudu and other Mongol generals were no longer unruly and acted according to orders.