The weather in western Sichuan has frost in the morning and evening, although it is not extremely cold, but the humid air and low temperature also make people stiff and cold. For Yang Sanwa and Li Laosi, who were lying in the cold grove in the middle of the night, they were even more cold at the moment, and their hands and feet were numb. They were two scouts of the 1st Infantry Brigade of the 2nd Division, and they were lying in the grove by the water. The night was deep, and with the faint starlight and the reflection of the river, they couldn't take their eyes off the other side of the river, and although they couldn't see it very clearly, even though they were very close. On the other side of the river is the boundary of Luojiang County in Mianzhou, which is under Mongol control. During this period of time, the Mongolian army carried out large-scale raids and harassment on the area under the jurisdiction of the Perak Army, and for a time hundreds of miles from Deyang in the north to Lingquan County in Chengdu Prefecture in the south, the warning bell of the Mongolian cavalry attack was frequently sounded.

In Mianzhu County, where the First Infantry Brigade of the Second Division was stationed, although there were only small-scale Mongolian reconnaissance and cavalry activities, and there was no major movement of the new annexed army on the opposite side, the brigade commander Zhou Jianshen did not dare to be careless. Although Zhou Jianshen was the new junior colonel of the uprising, he was promoted because of his repeated military exploits. In the face of Liu Daer's inducement to surrender, he made a plan for the Thunderbolt army to inflict heavy losses on the Mongolian army and the great victory in the Battle of Jiading, so he was promoted to brigade commander. The current cold temperature was good for the Mongol army from the bitter cold land, but not for the Thunderbolt army. The impact of the cold is secondary to the large drop in water levels in winter. Since the beginning of winter, the water level of Mianshui, as Ouyang Xuan called the Mianyuan River, has dropped by more than half. The river section of Mianzhu County, which is located upstream, has declined even more severely, and many places have been able to wade across the river. This not only made it more difficult to defend, but also severely limited the movement of the Thunderbolt ships.

On the one hand, Zhou Jianshen ordered people to dig the river to increase the difficulty of the Mongolian army crossing the river, and on the other hand, he added many secret posts to prevent the Mongolian army from crossing the river at night. Most of these outposts are located along rivers that are easy to wade across rivers, and are kept at a certain distance from the Perak watchtowers guarding the ferry. Although the Thunderbolts won the final victory in the Battle of the Three Water Crossings, the fortress was quietly raided by the Mongol army, which was obviously a serious lesson and was also written into the textbooks of the Thunderbolt Military Academy. In order to make up for this shortcoming, Zhou Jianshen ordered that multiple groups of secret posts were arranged around each guard tower to prevent the Mongolian army from sneaking attack.

Yang Sanwa and Li Laosi are one of the secret sentinels that monitor the enemy's movements. Half a mile to their right was the fortress of their platoon. Because it was a special period, a platoon stationed in this fortress had a third of the men on duty at night. There are three groups of clear sentinels on the fort, and six people are on duty, and there are one group of dark sentinels on the left and right sides of the fort. Such a requirement for duty is actually a request from the division headquarters. This place is twenty miles northwest of Mianzhu County, where the brigade headquarters is located, where the grass on both sides of the bank is deep and dense and the water is turbulent, which is not conducive to the activities of the Mongolian cavalry, so there was only one squad stationed before. Just two months ago, division commander Huang Dagen inspected here, and after inspecting the terrain, he took out a map and studied it with his entourage, and immediately asked for strengthening the defense. Therefore, the guard tower was increased to a fortress, and the strength was increased to a platoon.

Yang Sanwa unscrewed the wine gourd she was carrying, took a sip, and handed it to Li Laosi next to her. After Li Laosi took a sip, he carefully plugged his mouth again. In order to resist the cold of the winter nights, the Thunderbolts equipped the sentinels with coats and hats made of animal skins, as well as a small amount of liquor and fatty meat, and some of the sentinels even had ginger syrup, so that night duty was not only not a chore for the soldiers, but meant that they could have a good meal. At present, although the Perak army is not short of food, and also raises a large number of pigs, sheep, chickens, ducks and other domestic animals and poultry, and also purchases meat and animal skins and other materials from the Tibetan region, wine, meat and sugar are still luxury goods, mainly used for war needs, and are still rare in peacetime.

After a moment of drinking, the whole body warmed up. At this time, it is the time of the fourth watch, and it is also the time when people are most sleepy and sleepy. Yang Sanwa and Li Laosi's way to overcome drowsiness is simple and rude but very effective, that is, to pick each other's noses. Unexpectedly, this time Li Laosi made his hand a little heavier, and carried Yang Sanwa to tears, almost screaming in pain, but Li Laosi covered his mouth with his dirty hands covered with mud. The Perak Army has very high requirements for the guards on duty, not only requiring that they not doze off, but also that they cannot make big movements, otherwise the officers who will be inspected will find out that the punishment will be very serious and even expelled from the army. The pain and the dirt in his mouth made Yang Sanwa angry, and just as the boat of friendship was about to turn over, Li Laosi whispered in his ear, "Someone is wading across the river."

Li Laosi's words made Yang Sanwa suddenly quiet, and he immediately turned his head to the river. Since the winter, most of the river that was originally half a mile wide has become a river beach, and the river surface has become only more than ten meters wide, and the water has slowed down a lot, and it is no longer rushing. Yang Sanwa listened for a while, and then heard the sound of peaceful flowing water mixed with the sound of footsteps and water, and occasionally a low cry - although the river water only reached the thighs, the bottom of the river was covered with smooth pebbles of all sizes, and the water was cold and biting, so it was not easy to cross the river. Judging by the sound, there were no less than 100 people wading in the water. The two judged that the person who crossed the river at this time must be the Mongolian army, and immediately decided that Li Laosi would quietly return to the fortress to report the news, and Yang Sanwa would prevent the other party from going ashore here.

It is obviously impossible for Yang Sanwa to stop the Mongolian army from crossing the river alone. But the Mongol army had no idea that their whereabouts had been exposed, and as they crept to the shore, there was a sudden commotion in the grove above, followed by something falling, followed by a violent explosion. "One, two, three ......", Yang Sanwa reported the number while dropping the bomb. Before Li Laosi went back, he gave him all his grenades. When the number reached ten, Yang Sanwa knew that the bullets had been dropped, so she picked up the musket and fired at the figure below, shouting loudly as she fired. The sudden explosion and the sound of muskets made the Mongolian troops in the river beach completely stunned, and they retreated one after another, behind them were the wailing and screams of the wounded soldiers and the bluffing shouts of Yang Sanwa. It's just that the commander of the Mongolian army is not a fool, although he can't see the situation on the other side, he can judge from the thin shouts and scattered gunfire that the other side is not many in number, and he has to take advantage of the night to rush to the other side, if it is dawn, everything will not be easy.

After the gunshot, there must be a Mongolian soldier who was shot and fell to the ground, not because Yang Sanwa had excellent marksmanship and could hit the target in a hasty blind shot, but because the Mongolian troops who rushed over were too many and too dense. Yang Sanwa saw that the enemy was getting closer and closer, and the enemy soldiers who rushed to the front had climbed the river bank, and immediately turned around and ran. It's just that as soon as he ran out of the grove, he turned back—Li Laosi had already arrived with seven or eight soldiers, and as he ran, he took the grenade from his companion's hand, and took the lead in screaming and rushing towards the enemy on the bank of the river. At this time, on the top of the tower of the fortress in the distance, a bright peak fire rushed up. Wolf smoke during the day, pillars of fire at night, this is a warning to the distance. The peak fire was passed all the way, and it could be transmitted to Mianzhu within ten minutes, and Huang Dagen, who was stationed in Tunhan Prefecture, could receive a warning after half an hour.