What finally broke the stalemate between ruler and ministers—both sides stubbornly refusing to give an inch—was the luminous screen, which spoke in an unhurried, almost leisurely tone, as if it were calmly dropping trivia in a group chat.
[Lightscreen]
[From the Tang dynasty all the way to the present day, the story of Xue Rengui's "Three Arrows That Pacified Tianshan" has been passed around endlessly.
There is no question that it was a great victory.
However, if one zooms out and looks at the entire campaign instead of just that one highlight moment, the label "great victory" starts to feel… questionable.
After the three arrows beneath Tianshan shattered the enemy, yes, the Tang army won big—but the fundamental problem of being heavily outnumbered never actually went away.
Pursuit was unavoidable, yet bringing prisoners along was impossible.
Leaving them behind was even worse, because Xue Rengui worried that the captives might revolt and cut off the Tang army's retreat.
So, after some consideration, Xue Rengui gave the order: bury the prisoners alive, then continue the pursuit.
From that point on, the victorious Tang troops began to lose discipline. They hid spoils for themselves and privately abducted Tiele women.
Since a portion of these "private gains" was handed up to Xue Rengui, he pretended not to notice.
The end result was predictable: once Xue Rengui returned, the imperial censors impeached him.
Li Zhi eventually ruled that merit and fault canceled each other out—no punishment, no reward.]
The focus of Ganlu Hall instantly shifted, and Hou Junji once again became the man everyone looked at first.
Fortunately, they were all old acquaintances. Hou Junji merely swept his eyes over the crowd and then looked away. Soon, quiet side discussions broke out—everyone was whispering about the issue of killing surrendered troops.
Hou Junji let out a bitter smile. Life in Ganlu Hall was becoming more and more unbearable.
After this matter was settled, perhaps he should ask His Majesty for an external posting. Xiyu, Liaodong, Jiaozhou, Yizhou—anywhere was fine.
Anywhere but Chang'an. Anywhere but Ganlu Hall. He did not want to stay here for even a quarter-hour longer.
As for the other ministers, their worries were actually very straightforward.
Killing captives was ominous. And the lands around Tianshan were originally loosely administered frontier territories. To be this ruthless there—how could it not push people away?
Li Jing stroked his beard, his brows slightly furrowed, and chose to remain silent.
Li Shimin froze for a moment, then sighed and said,
"If Xue Li can be found, I'll have to trouble Yaoshi to put in some extra effort guiding him."
"Three Arrows That Pacified Tianshan" sounded heroic, sure. But three arrows causing a so-called army of a hundred thousand to collapse on the spot could only mean one thing: that army had never been united in the first place, and was already terrified of Tang.
Under those circumstances, why kill the surrendered at all?
There was no need to look far back. When they fought Xiao Lu Khan earlier, thirty thousand Tang troops had conscripted fifty thousand Huigu cavalry, forming an eighty-thousand-strong force to attack the Western Turks.
Back then, why didn't Tang generals worry that the Huigu cavalry would suddenly turn around and join the Western Turks to wipe them out?
When Wang Xuance, with only a handful of men, managed to rally nearly ten thousand vassal troops, why didn't he worry those men would stab him in the back?
Killing captives and allowing uncontrolled plunder—every possible way of sowing disunity had been used.
No wonder this campaign was remembered as one of the great shames of the Tang army.
Li Shimin sighed heavily. The more he thought about it, the more he felt that Tang's generals desperately needed proper education.
Then the luminous screen continued—and immediately proved that Li Shimin had still been too optimistic.
[Lightscreen]
[Regardless of everything else, Xue Rengui's "Three Arrows That Pacified Tianshan" was undeniably a major achievement.
With such a dazzling subordinate under him, the commander-in-chief, Zheng Rentai, could no longer sit still.
After breaking the enemy beneath Tianshan, Zheng Rentai and Xue Rengui split their forces to expand the results of victory.
The Tianshan where Xue Rengui made his name is now called the Khangai Mountains, located in present-day Mongolia—roughly four thousand Tang li from Chang'an.
As the commander-in-chief, Zheng Rentai commanded more troops and began searching northeast for enemy remnants.
By then, news of the Tang victory had already spread. When the northeastern Tiele tribes saw Zheng Rentai's army, they immediately chose to surrender.
For reasons unclear—perhaps Xue Rengui's earlier private plundering, perhaps Zheng Rentai's inability to establish authority after an unremarkable campaign—Zheng Rentai rejected their surrender. Instead, he followed precedent and allowed his troops to loot them.
The Tiele people scattered and fled.
At that point, Zheng Rentai received news that thrilled him: further north lay even wealthier Tiele tribes, with endless cattle, sheep, and women.
Without much thought, Zheng Rentai split his forces again. He left the infantry and remaining troops to encamp, while personally leading fourteen thousand elite cavalry northward in pursuit.
To move faster, he ordered the cavalry to discard their armor and carry only minimal supplies.
After all, the Tiele collapsed at first contact—once they reached those rich tribes, wouldn't they have everything they wanted?
Reality, however, had other plans.
Zheng Rentai chased north for over thirteen hundred li, all the way to the vicinity of Lake Baikal, and found nothing.
With provisions running low, he had no choice but to order a retreat.
But Tianshan lay over four thousand li from Chang'an, and between the long campaign and Zheng Rentai's greed-driven pursuit, winter had arrived.
On the battlefield, these elite Tang troops were death incarnate. Against nature, they were helpless.
Blizzards on the return march became their true nightmare. Supplies ran out quickly in the extreme cold.
First, weapons were discarded. Then, under desperate hunger, the army slaughtered its horses.
And when the horses were gone? "The starving devoured one another."
Zheng Rentai set out with fourteen thousand elite cavalry. In the end, only a little over seven hundred returned.
One greedy decision, plus an unexpected snowstorm, buried thirteen thousand three hundred of the finest light cavalry of the age.
When the censors impeached Zheng Rentai, they called it the greatest and most shameful defeat since the founding of the Tang.
Li Zhi, mindful that Zheng Rentai was an old subordinate of Erfeng, issued the same judgment as with Xue Rengui—no reward, no punishment.
One year later, Zheng Rentai died of illness in an official residence in Liangzhou and was buried alongside Zhaoling.]
Li Shimin opened his mouth, then closed it again. He genuinely did not know what to say.
He very much wanted to ask Du Ruhui whether the Guizheng County Duke title granted earlier that year could still be taken back.
Zheng Rentai had been one of his trusted men, and Li Shimin had once considered entrusting him with heavy responsibility.
But precisely because he knew Zheng Rentai so well, Li Shimin was not surprised that his name never appeared during Tang's great expansion.
When he heard that Zheng Rentai had been appointed to suppress a rebellion, he had even felt relieved—not because Zheng Rentai had improved, but because Li Zhi still remembered old ties.
The Huigu rebellion had never been united. It was practically free merit.
Xue Rengui at least walked away with a heroic reputation.
And Zheng Rentai still managed to mess it up.
Li Shimin even felt a grim sense of relief:
Good thing I didn't entrust him with anything important back at Xuanwu Gate…
Shaking off the thought, Li Shimin calculated angrily,
"According to the luminous record, from the destruction of the Eastern Turks to the capture of Xiao Lu Khan, we wiped out multiple states and opened up ten thousand li of territory. Even then, casualties in the Western Regions never reached this level!"
In his heart, the Tang emperor was already deciding where Zheng Rentai should have met his end.
Xuanwu Gate? Or Zhuque Gate?
Yet beneath the anger, unease lingered.
If even such a simple suppression could turn out this badly, it was not a good sign.
Nearby, Zhangsun Wuji quietly moved closer and said to the dazed Hou Junji,
"Zheng Guang isn't here. Does the Duke of Lu feel a bit disappointed?"
Zheng Rentai's original name was Zheng Guang. During the Xuanwu Gate Incident, both men had been planners, and thus knew the participants well.
"Mm… ah? Of course not!"
Hou Junji did feel a hint of regret—but admitting that was out of the question. He denied it instantly.
Zhangsun Wuji's round face clearly said "I don't believe you." He chuckled softly and silently moved away again.
The catastrophic defeat caused by the blizzard drained much of the earlier cheer from Ganlu Hall.
Li Jing spoke first.
"Perhaps…"
The old general thought aloud,
"When Your Majesty opens the civil examinations, you might also consider opening military examinations."
This idea had been circling in his mind for a long time, and he finally voiced it:
"In the Huigu rebellion, even a mediocre commander could have won. It never should have ended like this."
Li Shimin nodded slowly.
Zheng Rentai's mistakes were too numerous: rash advances, unverified intelligence, ignorance of terrain, failure to deploy scouts.
Forget commanding an army—whether he was even qualified to be a general was questionable.
Seeing Li Shimin's agreement, Li Jing continued,
"When it comes to defeating strong enemies, expanding territory, and destroying states, only famed generals like Maogong and Dingfang will suffice."
"Two hundred riders to destroy Xueyantuo; five hundred riders to charge into enemy ranks—these are Your Majesty's Wei and Huo."
Li Shiji and Su Lie straightened immediately, faces solemn, hearts secretly exploding with joy.
General Li Jing praised us personally!
"However," Li Jing continued, "when barbarians rebel, they never truly believe they can defeat Tang. They rely only on distance, gambling that Chang'an cannot spare attention."
"These rebellions are doomed from the start. As long as a commander follows military doctrine, victory is assured, with minimal loss."
He concluded,
"Therefore, opening military examinations may ensure that those who truly understand warfare become generals—and prevent disasters like this."
Li Shimin nodded decisively.
"Excellent."
Details could be refined later. The important thing was that the idea was sound.
Xue Rengui was the clearest example: a fierce, unconventional talent whom Li Shimin admired—yet his killing of captives and indulgence of plunder made the emperor's eyelids twitch every time.
Correcting the fundamentals of Tang's generals could not wait.
…
In the Chengdu prefectural office, Zhang Fei shook his head and sighed,
"This Great Tang—looks like even Heaven couldn't stand watching anymore."
Liu Bei disagreed,
"What does Heaven have to do with it? This is human disaster!"
As he spoke, he glanced at the ceiling, silently apologizing on behalf of his third brother—hoping Heaven would not get angry and reclaim the luminous screen.
"This truly is a man-made disaster," Kongming sighed.
"When Tang was founded, enemies surrounded it. The Son of Heaven had courage, the generals had strategy, and the soldiers dared to die."
"Now it has reached a state of 'no external enemies.' Commanders don't understand warfare, and generals chase merit."
"That Great Tang suffering a crushing defeat at the hands of Tubo," Kongming concluded calmly,
"is not far off."