Resolution: To Occupy Tuyuhun
Hou Junji and Li Chengqian were determined to make Li Zhi the target of public criticism. To this end, they even began desperately downplaying the importance of Tuyuhun. However, they had not anticipated that while Li Zhi might not be well-versed in other aspects of Tuyuhun, he certainly had a say in how that territory could be developed.
Li Zhi spoke up, saying, "Big Brother and General Hou are mistaken!" He then scanned the other ministers and proceeded to analyze the benefits that conquering Tuyuhun would bring. First, Tuyuhun was located near a vital passage of the Silk Road. Its stability was directly linked to the Tang Dynasty's overland trade. Since this concerned the interests of almost every minister at court, Li Zhi brought it up first. Secondly, the environment in Tuyuhun was suitable not only for animal husbandry but also for agriculture, making its geography even more favorable than that of Tubo. Furthermore, Tuyuhun possessed vast deposits of gold, copper, and iron—all of which were hard currency at the time.
If these were merely material factors, then the fact that the various ethnic groups within Tuyuhun had already undergone significant Sinicization was something no other nation could compare to. This meant that once the Tang Dynasty ruled over the region, they could save a great deal of time and energy on assimilation efforts. It would be far less troublesome than the previous campaign against the Eastern Turks.
The other ministers were indifferent to Li Zhi's other points, but they were captivated by the first. Consequently, as soon as Li Zhi finished his analysis, many civil officials stepped forward to support the occupation of Tuyuhun. Fang Xuanling and Zhangsun Wuji exchanged a subtle glance, the corners of their mouths curling into involuntary smiles. This protégé was truly worth the effort of competing for! To be able to grasp the political situation with such precision at such a young age—he was a rare political talent indeed.
Seeing that the other ministers also supported the occupation, Li Shimin turned to Li Tai, who had remained silent, and asked, "Qingque, what do you think? Should our Tang Dynasty launch a major offensive against Tuyuhun?" At that moment, Li Shimin had already made up his mind. He asked Li Tai this question solely to test his insight.
Li Tai was caught in a dilemma. His intuition urged him to stand with Li Chengqian, yet the potential benefits to the trade routes made him want to support Li Zhi. In truth, he had not fully grasped the deeper purpose behind today's debate, but his shortsightedness happened to inadvertently align with Li Shimin's intentions. Li Tai replied, "Your son agrees with the opinions of the generals." He even tried to be clever by deliberately avoiding any mention of Li Zhi’s contribution to the argument. Regardless, his answer satisfied Li Shimin, who nodded with a smile to show his approval. One might say that even the foolish can sometimes be blessed with good fortune.
Li Shimin then announced, "In that case, Li Jing shall serve as the Commander-in-Chief of the Xihai Expedition, leading Yuchi Jingde, Cheng Zhijie, and the Governor of Liangzhou, Li Daliang, along with the brothers Xue Wanche and Xue Wanjun, to punish Tuyuhun." The reason Li Jing was chosen to lead the troops was, first, Li Shimin’s absolute faith in his ability, and second, because he was more familiar with the Dragon Cavalry. Although Li Zhi was the de facto leader of the Dragon Cavalry, Li Shimin was not comfortable sending someone so young to the battlefield. Usually, it is the disciple who labors for the master, but here, the roles were reversed, with the teacher taking the battlefield on behalf of his student.
After announcing this appointment, Li Shimin, to balance the sentiments of the other military officers, arranged for Qin Qiong to lead a force to the Tubo border to defend against any opportunistic intervention by the Tubo army. Hou Junji, having explicitly voiced his opposition, was left behind to assist the Minister of Revenue, Wang Gui, in gathering provisions, leaving him no opportunity to distinguish himself.
The various generals were eager to claim credit, so only ten days later, Li Jing set off in a hurry with an army of one hundred thousand. Everyone had assumed this speed was fast enough, but halfway to their destination, they encountered a third report of victory forwarded by Li Daliang. Yuchi Jingde and the others grew anxious; if this continued, would there be any battles left for them to fight by the time they reached Tuyuhun? Thus, at the urging of the commanders, their already rapid pace was quickened further.
Li Jing made a rough estimate of the Dragon Cavalry’s offensive speed and reached an alarming conclusion: no matter how fast his army moved, they would never reach the battlefield before the Dragon Cavalry’s next move. He decisively dispatched a light cavalry unit of over a hundred men to Liangzhou City. He had to reach Li Daliang and command the Dragon Cavalry to slow down their offensive against Tuyuhun. Otherwise, he and Li Zhi would find themselves in a very awkward position later.
By this time, the joint forces of Su Lie and Qibi Heli had already arrived at Chishuiyuan. To their disappointment, the Tuyuhun main army, which should have been stationed there, was nowhere to be seen. Only a small number of laborers responsible for tending the horses and livestock remained, along with a garrison of fewer than five thousand men. Reconnaissance by the Dragon Cavalry confirmed that the main enemy force had retreated to a city a hundred miles away to regroup.
After conferring, the two commanders decided to ignore this enemy force for the time being to avoid alerting the enemy. They had no other choice; both armies were light cavalry and lacked the capability to build large siege weapons. Moreover, the Dragon Cavalry’s combat style was ill-suited for siege warfare. A forced assault would likely result in heavy casualties, which was a loss Su Lie could not accept—and which Li Zhi had repeatedly forbidden.
Furthermore, they had to consider another enemy force of twenty thousand stationed at Niuxindui. Even if they easily captured this camp and lured out the main enemy force, the two enemy detachments were too close to each other. If the enemy commander were cautious and notified the other force, the joint army could find themselves besieged by over thirty thousand enemy cavalry. In a head-on confrontation, they would have no chance of winning.
The tedious wait grew dull for both armies, and their supplies were rapidly depleting. A few days later, Su Lie and Qibi Heli were losing patience. Just as they were preparing to risk everything on a desperate gamble, the messenger sent by Liangzhou Governor Li Daliang arrived just in time. Upon reading the orders from Li Jing in the letter brought by Li Daliang, Su Lie and Qibi Heli broke into a cold sweat.