In order to ensure the internship of cadets, military academies generally have a unit under them. There is also a teaching regiment under the Datang Military Academy, which is specially used in conjunction with teaching exercises.

Li Xiaogong accompanied Lu Dongzan and his party to visit the tactical drill of the teaching regiment.

The teaching regiment dispatched 1,000 soldiers to practice the offensive operations of the cavalry and infantry of the Modao Formation, longbow fire strikes, field defense, bridge building, field logistics support and other subjects, which left a deep impression on Lu Dongzan and others.

When Lu Dongzan and others returned to the embassy of the Ministry of Foreign Affairs, they all felt a lot of pressure.

The deputy envoy of Tibet said: "Da Yan (Minister of Foreign Affairs), I know why the Tang Dynasty people invited us to visit their military exercises, and I am not afraid that we will know their secrets. This is because, even if we know their tactics, we can't do anything about them, let alone learn from them. ”

Lu Dongzan nodded and said: "Yes, the weapons in the hands of the Tang Army, such as what telescopes, we can't make in Tubo, even if some weapons can be made, we don't have so much steel, and we can't afford to equip them."

The Tang Dynasty was too advanced and wealthy, they had a large population, developed industry and commerce, and in the event of a war, they could casually arm millions of troops.

Tibet was so backward that if it fought a war with the Tang Dynasty, there was almost no possibility of victory. ”

The deputy envoy of Tubo said: "It seems that if we want to defeat Tuyuhun, we can only do it without the intervention of the Tang Dynasty, but will the Tang Dynasty intervene?" ”

Lu Dongzan shook his head and said, "It's hard to say." ”

The next morning, Lu Dongzan asked to see Tang Fei.

Tang Fei asked, "Lord Da Lun, what is your main mission when you come to Datang this time?" ”

Lu Dongzan said: "My family Zanpu (king) Songtsen Gampo admires the strong and advanced culture of the Tang Dynasty and is willing to make friends with the Tang Dynasty. In order to establish a close relationship with the Tang Dynasty, I specially asked His Majesty the Emperor of the Tang Dynasty for the princess of the Tang Dynasty, and asked the Minister to convey the thoughts of my family Zampu. ”

When Tang Fei heard this, his head shook like a rattle, and he said, "Lord Da Yan, do you know how the original Xue Yantuo Khan Yinan died? ”

Lu Dongzan said: "Didn't he die in battle? Could there be any other reason? ”

Tang Fei said: "His Majesty the Emperor of the Tang Dynasty and His Royal Highness the Crown Prince are both benevolent people, the Tang Dynasty has conquered the Western Regions and the Linyi Kingdom, and their kings have been treated well by the Tang Dynasty, have you heard of this?" ”

Lu Dongzan nodded and said, "I've heard of it." ”

Tang Fei said: "Why is it only Yi Nan who died? ”

Lu Dongzan and the others asked puzzledly, "Why?" ”

Tang Fei looked out the window and said a little nervously, "I'll tell you a secret." At that time, the Yi Nan Khan asked the emperor for marriage, but Princess An Ning was unwilling and almost died, and from then on, the emperor and the queen loved their princesses very much, and did not agree to marry them far away. His Royal Highness the Crown Prince has a close relationship with the princesses, and he disagrees with them leaving Chang'an.

Yi Nan Khan angered the emperor because he begged Princess Anning, but he did not accept Yi Nan's surrender and killed him directly.

You see, in the past ten years, has Datang had a princess and a kiss? ”

Lu Dongzan and the others were very depressed, knowing that this trip was in vain. However, he still wanted to explore the hole cards of the Tang Dynasty to see if the Tang Dynasty would interfere if Tubo attacked Tuyuhun.

He said: "Your Excellency, we have come to Datang and brought some gifts that we want to present to His Royal Highness the Crown Prince, please arrange them." ”

Tang Fei said: "This is easy to do, you just wait for my news." ”

In the afternoon of the next day, the East Palace.

Lu Dongzan saluted Li Su and gave him a gift.

Li Su looked at Lu Dongzan in front of him, and saw that he was talented, and his face was full of bookishness, and he first had a good impression of him. He said, "I have admired you for a long time, and it is a great honor to meet you. ”

Lu Dongzan thought he was saying kind words. He said in his heart: "I am a Tibetan and have never been to the Tang Dynasty, what can the prince of the Tang Dynasty admire himself?" He was thinking about a few polite words when he heard Li Su talk about his resume.

Li Su said: "Lord Dalun, you are 29 years old this year, a native of Rangba (now Liemai Township, Longzi County, Shannan Prefecture, Tibet Autonomous Region). The family inherited the fiefdom in the area of Gabe.

You are known as a young man with supernatural powers, proficient in Tibetan, Indian and Han cultures, and once sent an envoy to Nepal to propose peace to the king of Guangzhou, hoping to marry the princess Brikuti (the princess of the ruler). After three verbal battles, roundabout battles of wit, and threats with troops, King Guangzhou was forced to marry Princess Chizun to Songtsen Gampo......"

Li Su queried his information from Baidu and corroborated it through the Overseas Intelligence Bureau.

Lu Dongzan was taken aback, and then he deeply admired Li Su. He said: "Your Royal Highness the Prince, according to the Han nation, it is unthinkable that you know me so well. ”

Li Su asked Lu Dongzan for some information about the culture of Tibet, as well as the customs of Tibet, and between words, he knew the situation in Lhasa very well.

Next, they talked about cultural exchanges and trade between the Tang Dynasty and Tibet. During this period, he talked about the matter of Tuyuhun.

Lu Dongzan asked tentatively, "Is Your Highness familiar with Tuyuhun?" ”

Li Su smiled and said: "Nuo Hao Bo Khan and I are very good friends, a few days ago, he just sent an envoy to Chang'an, we have agreed to carry out joint military exercises, the exercise locations are in the Tang Dynasty Longyou Road, Anxi Duhufu, and Tuyuhun territory.

The content of the exercise was mainly highland and mountain operations.

You have come to Chang'an today, and I have a suggestion that the Tang Dynasty and Tubo should also strengthen military exchanges, so I invite the Tibetan army to participate in joint military exercises. ”

After listening to Li Su's words, Lu Dongzan felt cool in his heart, he had already heard it - the Tang Dynasty knew the situation in Tubo very well, and he had already mastered Tubo's attempt to use troops against Tuyuhun. The Tang army and the Tuyuhun army were ready to jointly counterattack Tubo.

He said to Li Su: "I am very much in favor of His Royal Highness the Prince's proposal, but this matter is important and cannot be decided by me as a courtier.

His Royal Highness the Crown Prince's proposal to strengthen cultural, commercial, and military exchanges between the Tang Dynasty and Tibet will be reported to Zampu as soon as I return. ”

Li Su said in some surprise: "Lord Da Yan, are you going back, don't you play in Chang'an for a few more days?" In a few days, I will marry a side concubine, and I hope you will be able to attend my wedding. ”

Lu Dongzan said: "Congratulations to His Royal Highness the Crown Prince, I am very willing to attend your wedding." However, I must go back, please forgive me. ”

Li Su said: "It's a little regrettable, but it's inconvenient for me to keep it when I talk about my lord's business." In this way, I have prepared some gifts, please bring your family Songtsen Gampo Zampu, and greet him on my behalf, and I invite him to visit Chang'an on behalf of His Majesty the Emperor of the Tang Dynasty. ”

After expressing his gratitude, Lu Dongzan took his leave.

When he returned to the pavilion, Lu Dongzan wrote a letter and sent someone to Lhasa immediately. He then led the mission back to Tibet. Before leaving, Tang Fei prepared a lot of precious glass products for them as a thank you for the gift from the Tibetan mission.

After receiving Lu Dongzan's report, Songtsen Gampo knew that the Tang army and Tuyuhun were ready for war, and the plan to attack Tuyuhun had to be abandoned.