Chapter 512: Cutting Off the Back Road

Distance was the main reason why Li Qing’an couldn’t obtain the latest intelligence. Chang’an was thousands of miles away from Toharistan. Even using carrier pigeons, it would take at least ten days or so, by which time the Anxi Army had already launched a war against the Tibetans.

Toharistan was divided into northern and southern parts by the Amu Darya River. Its main cities and states were located on both banks of the river, with most concentrated on the southern bank. On the northern bank lay states such as Jiesu, Wangting, and Gumo, among which Jiesu was currently occupied by the Tang Army.

Jiesu was situated on the southern edge of the Fergana Valley, where mountains stretched in succession, creating a highly complex terrain. There were snow-capped peaks and glaciers as well as deserts, with high mountain valleys stretching for hundreds of miles.

To the south of Jiesu lay Wangting, a highly important state in Toharistan. It had vast arable land and a highly developed agriculture. Its population was second only to that of the Yuezhi state, and its capital, Bushi City, was the second-largest city in Toharistan.

Due to Wangting’s crucial importance in Toharistan, the Tibetans stationed a large number of troops there. Over 40,000 Tibetan soldiers were stationed near Bushi City, the capital of Wangting. With the Tang Army targeting Toharistan, the first battle would be for Bushi City.

In March, spring had arrived in Toharistan. The spring breeze turned the banks of the Amu Darya River green. The ice broke, and the river water melted, rushing violently. The roar of the water could be heard from miles away as it crashed against the riverbed.

The Amu Darya River turned northward from Bushi City. The city and the river were about ten miles apart. Standing on the city walls of Bushi City, one could clearly see the turbulent river water in the east.

When the Tibetans deployed their troops, it was winter, and a thick layer of ice covered the river, making travel between the north and south banks easy. But as the river water melted, it became difficult for the Tibetan troops to cross. To strengthen communication between the two banks and prevent Wangting from being cut off, the Tibetan troops employed 2,000 craftsmen to build a floating bridge over a relatively flat section of the river at the confluence of the Amu Darya and its tributary, the Kul River. Forty flat-bottomed boats were connected by thick iron chains, forming an arch-shaped bridge. Wooden planks were laid across the boats, allowing the Tibetan troops to move quickly across. In less than the time it took to drink a cup of tea, 10,000 Tibetan soldiers could cross the river and head north.

Thus, this floating bridge became a key point of defense for the Tibetan troops. They stationed 10,000 elite soldiers near the bridge on the northern bank. If the Tang Army attacked the bridge, it would be impossible to take it down in a short time, allowing Tibetan reinforcements to arrive promptly.

The main force of the Tang army, numbering about 80,000 troops, had emerged from the valleys of the Lhasa region. Divided into two groups, 30,000 troops moved south along the Amu Darya River, approaching Bushi City, while another 50,000 troops swiftly captured Hulun City and continued southward to cut off communication between Gumo State and Wangting State, pressing toward Bushi City from the west. In this way, the two armies encircled Bushi City, making the Tang army’s intentions clear: to concentrate their forces and annihilate the 40,000 Tibetan troops near Bushi City.

Bushi City was in a critical situation. The Tibetan commander there had sent for help to Shangxi Dongzan in Ahan City as soon as he detected the arrival of the Tang main force. Three days had passed, and at a normal pace, the Tibetan reinforcements should arrive by the day after tomorrow after crossing the Amu Darya River.

Since sending messengers southward, the Tibetan commander Lunxi Zhu had stood on the city walls every day, gazing southward in anticipation of the arrival of reinforcements.

Meanwhile, the Tang army’s commander, Li Qing’an, had arrived at the Tang camp about thirty li west of Bushi City. To the west from there lay flat plateau terrain, ideal for cavalry battles.

Inside the main tent, Li Qing’an was intently studying the situation surrounding Bushi State using a sand table. Several generals stood behind him, one of whom was Tian Qianzhen, a general who had defected from An Lushan. After An Lushan’s failed campaign in Guannei Road, Tian Qianzhen led his troops to surrender to Li Qing’an. At first, Li Qing’an was not confident in him and appointed him as a deputy under Li Fei Yuanli, tasked with building the Tang Straight Road. But as Li Qing’an returned westward, 10,000 Tang troops from Hexi also rushed to Anxi to assist in the battle under Li Fei Yuanli’s leadership. Tian Qianzhen volunteered to go to Anxi to earn merits, and Li Fei Yuanli agreed to his request, taking him back to Anxi. In the battle of Qiemo City, Tian Qianzhen led 3,000 Tang troops to charge into the Tibetan ranks first, killing numerous enemies. It was through this battle that Tian Qianzhen won Li Qing’an’s trust, and he was promoted to lieutenant general to join the attack on Toharistan.

Tian Qianzhen was talented in both civil and military affairs, skilled in warfare, and was known as the second-best general in Youzhou—meaning his status in the Fanyang army was second only to Shi Siming. Although he had long served under An Lushan, Tian Qianzhen was a man with great ambitions; he also longed to expand the territory of the Tang Dynasty and leave a lasting legacy.

Although historically Tian Qianzhen followed An Lushan in rebellion and achieved remarkable military feats for him, the course of mid-Tang history changed with the arrival of Li Qing’an, and Tian Qianzhen’s fate was altered as well. Whether it was Yan Zhuang, Cui Qianyou, or Tian Qianzhen, they were all like sharp knives—the knives themselves were innocent; it depended on who held them. When An Lushan held the knife, it became a butcher’s blade used to slaughter ordinary people, plunging them into the darkness of history. But when Li Qing’an held it, they became weapons for expanding the Tang Empire and earning fame.

At that moment, Tian Qianzhen silently watched the sand table, whose details were extremely thorough—each location’s Tibetan troop strength was marked by small flags. Although Li Qing’an hadn’t explained anything to everyone, Tian Qianzhen understood his strategy. After the Tibetan king was assassinated, many Tang generals strongly advocated attacking the Tibetan forces immediately, including key commanders like Li Fei Yuanli and He Ba Yurun. Yet Li Qing’an remained inactive, leaving many puzzled.

But Tian Qianzhen understood why Li Qing’an stayed still. First, since the king had just died, the Tibetans were eager for revenge and in high morale, so it was better not to attack yet. Once the Tibetan forces calmed down, internal divisions might arise due to the king’s death. Attacking prematurely would only unite the Tibetans against them, overriding their differences. Thus, Li Qing’an’s inaction was actually a clever strategy of using stillness to control movement.

Second, Li Qing’an was waiting for the Amu Darya River to recede, naturally splitting the Tibetan forces in two. This would allow the Tang army to concentrate its forces and defeat them one by one—a strategy Tian Qianzhen highly approved of. Because he understood Li Qing’an’s strategy, Tian Qianzhen felt a sense of mutual respect and admiration. Following such a commander would be more promising than following An Lushan. Though he was originally a general but now only a middle-ranking officer, Tian Qianzhen didn’t mind; he only hoped for more opportunities to earn merits.

Unable to hold back any longer, Tian Qianzhen quietly suggested, “General, I recommend building a floating bridge in Damo City immediately. Before the Tibetans discover our strategy, our vanguard can cross the Amu Darya first.”

Li Qing’an turned to look at him and asked with a smile, “What if we besiege the city and attack their reinforcements? Once the Tibetan reinforcements head north, we destroy their floating bridge and cut off their retreat. How does that plan sound?”

Tian Qianzhen was stunned by Li Qing’an’s bold plan, but he quickly regained his composure and said, “I think this plan is too risky and not very advisable.”

“Tell me, where exactly is the risk?”
Li Qing’an stood up straight and smiled at everyone, “Let’s all listen and pool our wisdom!”
People gathered around. Encouraged by the commander, Tian Qianzhen’s face turned red as he said, “The problem is we don’t know how many reinforcements the Tibetans will send. If it’s ten to twenty thousand, we might still be able to fight. But if they send over fifty thousand, the military balance will be unfavorable to us. If we divide our forces, they can easily defeat us one by one. Moreover, once the Tibetan army crosses the river, they’ll shift the battlefield northward. The river won’t split them up, so it won’t serve as a barrier. Therefore, I believe this plan is too risky. For the general to adopt it would bring more harm than good.”
He Ba Yurun, who was nearby, was unconvinced. Crossing his arms, he asked, “What if the Tibetan reinforcements are only twenty to thirty thousand? Wouldn’t it be better to let them cross the river?”
Tian Qianzhen shook his head. “It’s impossible to have only twenty to thirty thousand. Bu Shi City already has forty thousand troops. Following the principle of equal reinforcement, they’ll send at least forty thousand more. If they send only twenty to thirty thousand, those reinforcements would be pointless.”
“You’ve never fought against the Tibetans—how do you know their habits?”
“Enough, let’s stop arguing.”
Li Qing’an saw that the other generals looked down on Tian Qianzhen, likely because he was a defector. He interrupted them and said, “I’ve already received messages from scouts. Shangxi Dongzan has assembled fifty thousand troops to reinforce A Huan City, and they’re now 130 li south of the bridge. What worries me now isn’t the Tibetan reinforcements crossing the river northward, but the Tibetan troops in Bu Shi City retreating southward once the reinforcements arrive. That would put us at a disadvantage. So I’ve decided we must destroy the floating bridge as soon as possible.”
With that, he turned to Tian Qianzhen and smiled, “General Tian, Damo City has only four thousand Tibetan troops. I’ll give you six thousand. You must wipe out all the Tibetan troops there and use that place to build a floating bridge for our army. If you succeed, I’ll recognize your great contribution.”
Tian Qianzhen was thrilled. He quickly bowed and said, “I shall obey orders!”
But Li Qing’an wasn’t done. He added calmly, “If you fail, I’ll still hold you accountable for your failure!”
……

The floating bridge built by the Tibetan army to connect the north and south was located on the Amu River, 30 li southwest of Bushi City. Composed of 40 wide-bottomed boats, the bridge had a broad deck that could accommodate three warhorses side by side. This bridge was essentially a lifeline for the Tibetan army. Ten thousand Tibetan soldiers guarded the area north of the bridge and built fortifications there. Even if the Tang army used fire attacks, their arrows could hardly reach the bridge deck. The south side of the bridge was also heavily guarded.

By this time, the troops guarding the bridge had received news that Shangxi Dongzan, leading 50,000 reinforcements, was already 120 li south of the bridge. The vanguard would reach the bridgehead in at most half a day. Shangxi Dongzan ordered them to tighten their defenses and prevent the Tang army from destroying the bridge.

The Tibetan army immediately dispatched over a dozen patrol teams to scout the surroundings and sent a thousand men to patrol the bridge to stop the Tang army from sabotaging it from the river. They had thought very carefully, and their predictions proved correct—the Tang army indeed intended to attack the floating bridge from the river. At noon, when the wind on the river was at its weakest, two small boats suddenly appeared about two li upstream, moving swiftly and steadily downstream.

Since the floating bridge was built in a section where the current was relatively calm, and this calm stretch was quite long—about five or six li—there were rocky areas and rapid currents further upstream, making it impossible to sail. Clearly, these two boats had set out from two or three li upstream. The Tibetan army had anticipated this and deployed nearly a thousand sentries in this calm stretch upstream. Yet, no plan is foolproof; they failed to consider the opposite bank. It was an instinctive assumption that the Tang army would operate on the north bank and not appear on the south bank.

Unexpectedly, a Tang army scout launched an attack from the south bank. Each of the two small boats contained a Tang soldier with excellent swimming skills, tasked with lighting the fire bombs aboard. The boats were equipped with special canopies, and mannequins were placed in all directions to protect them from Tibetan arrows and water attacks. By then, the Tibetan soldiers patrolling the bridge had spotted the boats. They drew their bows, ready to defend themselves, with many also holding basins to extinguish the fires on the boats.

As the two boats drew closer, coming within 70 steps, the Tibetan soldiers fired a barrage of arrows. The dense rain of arrows struck the canopies and mannequins with clanging sounds. Instantly, the boats were covered in arrows, but they failed to harm the soldiers inside at all.

Thirty steps had been covered. Two Tang soldiers spotted through the gap that they were approaching the floating bridge. Almost simultaneously, they lit the fuses of the Thunder Bombs on the boats. Immediately, white smoke billowed up from the boats with “whoosh! whoosh!” sounds. The two Tang soldiers flipped over and fell into the river. As soon as they were in the water, they swam frantically to either side, well aware of the destructive power of the Thunder Bombs.

The fuses were only one foot and five inches long, exactly matching the distance of thirty steps. To destroy the floating bridge, Tang scouts had conducted multiple tests upstream. The bridge was already crowded with hundreds of Tubo soldiers, each holding a basin of water, ready to douse the flames once they started.

When the boats touched the bridge surface, hundreds of basins of water were poured at once. At that exact moment, the two boats exploded—successively. Each boat carried three Thunder Bombs. Bright red lights burst forth from the boats, and massive shockwaves shattered the boats and the floating bridge into pieces. The explosion sounded like thunder, with thick black smoke rising into the air and towering white waves splashing up more than ten feet high. Many Tubo soldiers were flung into the air, their screams drowned out by the deafening explosions…

The Tubo soldiers on the shore were stunned. Even the veterans who had fought in the Battle of Shibu City cried out in terror, “Thunder bombs! The Tang army’s thunder bombs have arrived!”

Many Tubo soldiers became panicked, thinking that the Thunder God was at work. They knelt down and kowtowed desperately, begging the Thunder God for forgiveness.

As the smoke dissipated, the floating bridge was torn apart into two large gaps, each over twenty feet long, breaking it into three sections. The longest section, no longer restrained, drifted downstream with its chains, while the other two sections were carried by the river current to the banks on either side. The floating bridge had completely disappeared from the river surface. The water was filled with debris from the boats and the severed limbs of Tubo soldiers, drifting downstream.

Nearly ten thousand Tubo soldiers silently watched the tragic scene on the river, a sense of foreboding rising in their hearts.