Harold held the Caliph's handwritten reply to him, and the words of praise on it kept him awake at night.

In his letter, the caliph fully affirmed his achievements and encouraged him to make persistent efforts to master more industrial, commercial, and military science and technology of the Tang Dynasty.

In the last sentence of the Caliph's letter: "You are my good son, and in that far east, take good care of yourself, take care of your body, and especially your safety."

Your mother is very good, and I will take good care of her. ”

In Harold's mind, the caliph was a god-like being. From an early age, he could expect to receive the caliph's attention, even if it was a glance.

Since he came to Chang'an, he has really received the attention of the caliph, and this kind word made Harold tearful and enthusiastic.

After the formation of the Chang'an Three Heroes, Qin Huaiyu and Huangfu Xin were also full of passion, and they always wanted to emulate the three evils of Chang'an by Li Su and others, and do something vigorous.

During the recess, Huang Fuxin said: "Big brother, second brother, we Chang'an Sanxiong have to do something so that we can make our name." ”

Qin Huaiyu also said: "Yes, the emperor was the same age as us, and he had already done great things for the country, so we should also do it vigorously." ”

Harold shook his head and said, "You Han people have a saying, just be a hero in the times."

In the current environment, we don't need to worry about national affairs, we are students, learn scientific and technological knowledge, and have the ability to do great things in the future.

I have found that the contribution of scientific knowledge to a country is sometimes greater than that of going into battle in the army. For example, if you invent a good product, you can build a lot of factories, feed a lot of people, and create a lot of wealth.

I propose that we set up a three-person scientific research group not only to learn the knowledge in the textbooks, but also to strengthen social practice. ”

Harold was the backbone of the trio, and Qin Huaiyu and Huangfu Xin agreed with him.

Sure enough, after they set up a three-person research team, they were praised by the school and teachers.

Harold's school is next door to Chang'an Industrial City, and Harold proposed that the three-person scientific research team should increase practical activities and visit the industrial city in their spare time.

Huangfuxin said: "This matter is easy to do, my father is in charge of the Ministry of Science and Technology and the Ministry of Industry, and I will arrange this matter." ”

Hou Junji commanded the Northeast Corps of the Tang Army, and crossed the Jinsha River on a front of more than 220 kilometers from Batang to Derong, and the speed of progress was not fast.

The Northeast Corps' march route had complex terrain, and at a distance of more than 100 kilometers, there were three major rivers, the Jinsha River, the Lancang River, and the Nu River.

The resistance encountered by the Don army was slight, and most of the time was wasted on the march.

On the morning of July 29, on the banks of the Lancang River.

In order to conquer Tibet, Hou Junji specially transferred his righteous son Hou Yingjie from Goguryeo and served as a pioneer officer.

On this day, Hou Yingjie commanded the vanguard of the Tang Army to cross the Lancang River from the Renguo area.

Lou Xianzhi is one of the four famous generals of Tibet and is currently the commander of the Eastern General's Office.

He stood on the hillside, observing the movements of the Tang army.

His lieutenant general, seeing that part of the Tang army had already crossed the Lancang River and landed on the riverbank, said to him:

"Great Commander, now that the Tang Army is crossing the river, let's attack now, just halfway through, we can hit the Tang Army hard!"

Lou Xianzhi shook his head and said: "Don't worry, it is true that attacking now can repel the Tang army, but the number of them crossing the river now is too small, and if they attack now, it will be difficult to achieve big results, and it will not constitute a major blow to the Tang army."

When all their vanguard troops cross the river, we will attack again and completely annihilate his vanguard troops, and we can severely defeat the spirit of the Tang army. ”

At this time, behind them, more than 50,000 Tibetan troops were assembled, including 30,000 cavalry teams and two infantry regiments of 10,000 people.

Lou Xianzhi's goal was to annihilate about 20,000 Tang troops at a time.

Lou Xianzhi and others saw that the Tang army lined up while crossing the river to cover the follow-up troops to continue to cross the river.

Hou Yingjie's vanguard force totaled 20,000 people, consisting of two cavalry regiments, four infantry regiments, an artillery regiment, and an engineer regiment.

After Hou Yingjie crossed the river, the head of the reconnaissance section of the vanguard reported to him that on the hillside ahead, the army of the Tubo people, about tens of thousands of people, had been discovered.

Hou Yingjie commanded the troops who had already crossed the river, and at a distance of one kilometer from the riverside, they lined up their military formations and prepared to meet the attack of the Tubos.

When Lou Xianzhi saw that there were about 20,000 Tang troops who had already gone ashore, only about 10,000 people were lined up in front, and the rest were marching or carrying supplies.

This is a good fighter, Lou Xianzhi decisively ordered the whole army to attack, he wanted to crush the Tang army that had not gained a firm foothold in one fell swoop, and completely annihilate them.

The Tibetan cavalry overwhelmingly rushed towards the Tang army, and their infantry followed closely behind the cavalry.

Soon, the Tubo cavalry who rushed to the front found that the front of the Tang army's Tang army formation was all cavalry, which was the favorite formation of the Tubo people.

When attacking the enemy's military formation, the cavalry rushing in front was the last thing they wanted to see was the enemy's spear formation.

The dense slanted spears were the nightmare of the charging cavalry. In such a formation, it is difficult for the cavalry who rushed in front to survive, and only by relying on the impact force they exchanged their lives for to destroy the opponent's spear formation, the cavalry behind can attack the opponent's military formation.

Now this situation is cavalry against cavalry, and there is a burst of ecstasy in the hearts of the Tibetan people.

Just when the Tubo cavalry rushed to a distance of only about 150 paces from the Tang army, the Tang cavalry suddenly turned its horse head and retreated.

The Tibetans thought that the Tang army was scared, and became more and more excited, and they rushed forward with a loud shout.

When rushing to the front of the Tang army, the Tibetans found that there was a rolling barbed wire fence more than one meter high on the Tang army's position, and there were many gaps in the middle of these drum barbed wire.

The Tibetan cavalry who rushed to the front didn't know what it was at first, but when they rushed to the front, they discovered the horror of these roller barbed wire.

Many cavalrymen collided directly with the barbed wire, and the horses were pierced and bruised all over their bodies, and the pain was unbearable and miserable.

Many of the cavalry also fell to the barbed wire, and they were not as rough and thick as the horses, and the result was even more miserable.

Among the cavalry of Tibet, many of them took off in the air, trying to leap over these obstacles in front.

As a result, the height of the drum barbed wire was just beyond the reach of war horses, and many Tibetan cavalry hung directly on the barbed wire.