The Tianxia system of the Tang Empire has never been maintained solely by force, and enwei and shi are the royal way they practice.
Therefore, when Li Shimin heard that Gao Changguo had blocked the commercial passage between the Western Regions and the Central Plains, he decided to recruit Qi Wentai, the king of Gaochang, into the dynasty, and to persuade and educate him in accordance with the principles of punishing the former and the latter, curing the sick and saving people. However, Qi Wentai said that he was sick and directly closed the window of dialogue.
Judging from the later situation, it should be true that Qi Wentai was ill, but his contempt for Datang was also obvious. The reason is actually very simple, because at this time Gaochang has already worshiped the new mountain, the Western Turks.
At this time, Li Shimin became more angry and was determined to completely solve Gao Changguo and turn it into a direct territory of the Tang Dynasty. Therefore, he appointed Hou Junji as the commander-in-chief of the Jiaohe River March and led a large army to pacify Gaochang.

Qi Wentai, a man who had always thought that he was very strategic, was very calm after receiving the news of Tang Jun's dispatch, telling his courtiers not to worry.
He analyzed that the Tang Dynasty was seven thousand miles away from us, of which two thousand miles were desert Gobi, there was no water and grass on the ground, the weather was bad, and the large troops could not march. Earlier, when I went to the Tang Dynasty, I saw that the area north of Qin and Long, the cities were depressed and sparsely populated, and they could not be compared with the Sui Dynasty. Now the Tang Dynasty sent troops to attack, and the supply of grain and grass was not enough, and the strength of less than 30,000 troops was enough to cope. So we can sit back and wait for them to get tired. Even if they were to come to the city for no more than twenty days, they would have to retreat after the grain and grass were cut off, and there was nothing to worry about.
It should be said that this analysis is still very reasonable. The bad thing is that his understanding of Tang is still stuck in the impression of "before". At this time, it was the thirteenth year of Zhenguan, and the national strength of the Tang Dynasty had entered its peak, just like the Han Empire during the Han Dynasty of Emperor Wu of the Han Dynasty, it was fully capable of supporting a large army to expedition to the north of the desert.
However, this is also a conclusion obtained from the results, when I read this paragraph, I was still very surprised, thinking that this Qi Wentai was of a very high level and would be Hou Junji's fierce enemy. Unexpectedly, this person was a spoiler in his bones, and when he learned that the Tang Dynasty army had already entered the mouth of Linmoraine (present-day Linmoraine, Shanxi), he was terrified and helpless, and finally fell ill and died.
After Qi Wentai's death, his son Zhisheng was able to take the throne.
In the fourteenth year of Zhenguan (640), Hou Junji and others led their troops to Liugu, and Tanma Yu reported that Qi Wentai would be buried, and the people of Gaochang would gather together at that time. So some people suggested that taking the opportunity to launch an attack could defeat the opponent in one battle.
But Hou Junji did not agree to this.
He believes that Tang Jun is a righteous master who has rejuvenated his teachers and asked for his sins, and if he sneaks in at his tomb, he will lose the commanding heights of morality, and such a victory will be easy to fight, but the people's hearts will be difficult to harvest.
"I led the king's division here, and it is sooner or later to conquer the opponent, and there is no need to rush it for a while."
Therefore, Hou Junji ordered the army to beat gongs and drums and stride forward to Tiandi City (田地城, in present-day Lukeqin, southwest of Shanshan County, Xinjiang).
Arriving at the field, Hou Junji decided to give his opponent a chance to send someone to persuade the defenders in the city to surrender, after all, the soldiers who surrendered without fighting were the best policy.
The field keeper replied crisply—never surrender.
He did this with confidence. Because the field city was tall and strong, easy to defend and difficult to attack, and the city was rich in grain and grass, and could eat for a year and a half, he believed that as long as it held out for a period of time, the Tang army would not be able to afford it and had to withdraw.
His idea was indeed good, but unfortunately, his opponent was the Tang Dynasty, not only the leader Hou Junji was an outstanding general, sitting in the base camp, but also the great military commander Li Shimin, whom Mao Zedong called the unparalleled right of the ancient army.
Before the Tang army set out, in addition to mobilizing enough grain and grass for Hou Junji, Li Shimin also gave him a special team.
This team is a worker from Shandong, and they are all good at making engineering equipment.
The workers cut wood to fill the moats and made carts to ram the towers. Immediately afterward, the Tang army threw stones into the city with a throwing cart, and piece by piece of stone fell from the sky, smashing the defenders' heads. So someone used his brain to put a felt over his head to cover the falling rocks. It seems that once people are in a hurry, their IQ is also in a hurry. Felt is used to block knives and arrows, block big stones...
The defenders of the city had no foothold, and the Tang army marched up and down three roads at the same time, and soon conquered the city, capturing more than 7,000 men and women.
Hou Junji immediately took advantage of the victory and marched into the army and besieged the capital of Gaochang.
The good man did not eat the immediate loss, and The new king of Gaochang, Qi Zhisheng, decided to take a soft first. He wrote to Hou Junji, saying that the former king was rude to Tang Tianzi and that he had just succeeded to the throne without any fault, hoping that Hou Junji would be merciful to his subordinates.
Where is Hou Junji so good to flicker? He immediately wrote back to Mi Zhisheng and told the other party that if he was sincerely repentant, he would go to the gate of my camp and surrender.
But Mi Zhisheng was obviously not ready to surrender, because he felt that he had not yet reached the point of despair, after all, he still had a hole card that had not been revealed.
Hou Junji is a lord who does not talk much about himself, and since he does not surrender, let's start fighting.
So his old routine began to play out again, ordering soldiers to fill the trenches; hit the wall with carts; and attack the city by throwing carts and stones. One fill, two hits, three stones thrown, all of which are standardized processes.
But after all, the capital city is relatively large, and the stones of the Tang Army are not cruise missiles, and they cannot automatically navigate and find the target. However, this is also easy to do, the engineering team of the general manager of the Waiting University is not white belt, and soon built a ten-zhang-high tower, overlooking the city, commanding the stone throwing army to strike accurately, and also friendly reminding pedestrians in the city not to walk randomly, to take shelter indoors, so as not to be injured by mistake.
Soon, the Gaochang defenders could not resist.
At this time, Qi Zhisheng complained in his heart that his father, didn't Gao Chang worship the mountain? At this time, not a single reinforcement came. Knowing that this is the case, Lao Tzu still resists a fart?
It was reasonable for Qi Zhisheng to feel angry, and it was reasonable that Qi Wentai had made an agreement with the Western Turks that if Gaochang was attacked, the Western Turks would come to the aid.
The problem is, when he heard that Hou Junji had arrived, the Western Turk Khan was so frightened that he fled west for more than a thousand miles, and he did not dare to stay in his own land.
Mi Jisheng lost aid and could not hold on any longer, so he had to surrender Kaesong. Hou Junji then divided his forces to pacify all parts of Gaochang, and the state of Gaochang was destroyed. Hou Junji captured Qi Zhisheng and his hundred officials, and carved Shi Jigong's class to return to the dynasty.