Before dawn had even broken, the entire Linbei City was already fully awake.
There was none of the usual bustle in the streets and alleys, only the orderly, heavy footsteps of patrols in armor crossing the bluestone pavement.
Today was the day the Northern Frontier’s first Light Network would officially conduct its initial transmission test.
The candle in the study of the East Courtyard had nearly burned down to its base.
Xia Lanshi had barely slept the entire night, his lips pressed into a tense, straight line.
Again and again, he checked the communication procedures, signal frequencies, and emergency protocols for each observation post, his fingers gripping the record book tightly.
What he was worried about was not whether the technology would work.
He was afraid that the entire system he had painstakingly written would collapse spectacularly once put into practice.
If anything went wrong, he would be the first person questioned.
Xiao stood by the window with his arms folded, looking through the half-open wooden lattice at the whitening sky.
His voice was calm as he said, “You don’t need to look at it anymore. The real test has never been whether the light can shine.”
Xia Lanshi’s fingers paused as he turned a page, and he looked up at him.
“As long as sunlight is reflected through the signal mirror and precisely aligned with the focal length, it will naturally shine.”
Xiao turned around. His deep eyes held the calmness of someone who had seen through the ways of the world.
“But people get nervous. They make mistakes. At critical moments, they forget the order in which signals are supposed to be transmitted. The most precise things in this world can perhaps be manufactured, but the least reliable thing has always been people.”
Xia Lanshi was silent for a moment before closing the record book.
“That’s why I established all these rigid rules. The rules are meant to restrain the uncontrollable human heart.”
“Don’t worry. I’m here.”
The corners of Xiao’s lips curved slightly as he walked over and extended his distinctively jointed hand toward him.
“Come on, my Chief Administrator. Let’s get the test done quickly, then come back and get some sleep.”
Xia Lanshi gently placed his hand in Xiao’s, and the two headed together toward the testing site.
◇◆◇◆◇
Before dawn broke, the observation platform of Linbei City was already crowded with people.
Xiao Yuan, Xia Lanshi, Su Muchen, Pei Yi, Qin Feng, Chi Banyue, as well as several military commanders who had guarded the Northern Frontier for many years, had all gathered there.
Everyone participating in the test held military binoculars.
The bitter wind cut through them, making everyone’s cloaks snap and billow, but no one complained about the cold. Every gaze was fixed tightly on the mountaintops to the north, shrouded in the morning mist.
No one knew whether this would work.
Would this idea that surpassed its era really be able to operate in actual combat?
No one knew the answer.
Qin Feng was especially tense. He gripped the pen he was using to record the results in one hand, while holding the binoculars in the other, staring through the lenses at the distant mountains without blinking. His face was as tense as a piece of wind-dried stone.
Unable to resist, he swallowed and lowered the binoculars for the third time, turning to Pei Yi beside him.
“General Pei, do you think… with the fog this thick, we’ll really be able to see it?”
Pei Yi likewise held his binoculars up, staring straight ahead without moving his gaze.
“I don’t know.”
Cold sweat appeared on Qin Feng’s forehead, and even his voice sounded unsteady.
“Then… what do we do if we can’t see it?”
Pei Yi glanced at him, his tone blunt.
“Start over.”
Qin Feng: “……”
Chi Banyue, on the other hand, was not anxious.
Their Secret Guard Camp had already spent this period studying all kinds of applications for the sunlight signal mirrors. They had even begun using them for communication among the Secret Guards.
She looked at the two nervous generals beside her and could not help shaking her head.
The sun had not even risen yet. What could they possibly see by staring through binoculars right now?
As the sun was about to rise above the horizon, Xia Lanshi took a deep breath and turned toward Xiao Yuan, who stood at the very front with his hands behind his back.
“Your Highness, the time has come. May we begin?”
Xiao Yuan’s deep black eyes, dark as a frozen abyss, remained quietly fixed on the north.
After a moment, his low, calm voice came through the wind.
“Begin.”
◇◆◇◆◇
At the same time, dozens of li away, on the mountaintop of the Northern Watchpost.
The young soldier responsible for holding the mirror had palms slick with cold sweat. He gripped the mirror in front of him so tightly that he barely dared to breathe, his hands tense enough to tremble slightly.
Behind him, a veteran who had fought through countless battles placed a hand on his shoulder.
His voice was low and hoarse.
“Don’t rush. Keep your hand steady. Wait for the sun.”
◇◆◇◆◇
Time passed second by second.
The surroundings were so quiet that only the howling wind could be heard.
Far away, thick morning mist lay over the snowy mountaintops like cotton, blocking all visibility across the dozens of li between them.
As the sun slowly rose above the horizon, golden sunlight finally pierced through the thin mist and spilled across the snowy peaks.
Everyone held their breath.
One breath.
Two.
Three.
Far away, there was still no movement.
Qin Feng’s fingers around his pen had begun to tremble slightly from gripping it too hard.
An uneasy stir began spreading through the crowd.
“What happened? Did frost form on the high-altitude mirror?”
“Or is the fog too thick? Can the Northern Watchpost simply not see us?”
Several commanders had already begun frowning and were raising their hands, preparing to summon a messenger.
Just as everyone’s confidence began to waver, just as they were beginning to believe that this epoch-making experiment was about to end in failure—
On the highest watchpost in the distance, hidden among the vast morning mist and snow-covered peaks, a white radiance suddenly burst forth without warning.
It was neither beacon fire nor lightning.
It was a dazzling white brilliance that tore through the air from the boundary between heaven and earth.
It was as though someone had lit a star in the lonely, freezing lands of the far north, tearing through the morning mist.
The light passed precisely through the mirror, flashed once, then shifted and disappeared.
The fastest light in the world had, at this moment, been given a soul capable of speaking the language of humanity.
The observation platform fell into deathly silence.
No one cheered.
No one applauded.
Everyone was stunned, so stunned that they even forgot to breathe.
Even Xia Lanshi, who was always calm, froze for an instant before that first beam of light.
“One light!”
Only when the light disappeared did he suddenly recover, shouting those two earth-shaking words with nearly all his strength.
Then came the second flash.
It lit up, then disappeared.
The third.
It lit up, then disappeared.
The fourth.
According to the agreed decoding sequence, the white light flashed precisely four times within an extremely short period.
Each flash was like an invisible hand knocking heavily upon a massive door across the snowy mountains and freezing winds dozens of li away, striking the sleeping land of the Northern Frontier.
The sight was almost brutally shocking, striking directly at the hearts of everyone present.
And yet this was not even the most astonishing part.
After a brief silence, Xia Lanshi immediately issued a sharp command.
“Transmit back!”
This was the greatest part of the entire Light Network.
It was not a one-way transmission of information, nor a beacon fire that went out without return.
It was two-way communication capable of “conversation.”
The testing personnel at Linbei City immediately followed the agreed procedure. They adjusted their sunlight signal mirrors, precisely reflecting the rays of the rising sun and sending a signal back.
Linbei City: Received.
Northern Watchpost: One light.
Immediately afterward, Linbei sent the two-light signal again.
The entire platform held its breath.
Everyone raised their binoculars and stared fixedly at the distant mountaintop.
◇◆◇◆◇
Far away, on the mountaintop of the Northern Watchpost.
Through his binoculars, the young soldier watched the two white flashes appear faintly in the direction of Linbei.
Suddenly, he smiled.
As he smiled, large tears began falling onto the cold snow.
He thought of the brothers who had died because they had been unable to wait for reinforcements.
Beside him, the veteran’s eyes reddened. He patted the young soldier on the shoulder and quietly said three words.
“We received it.”
They both knew.
This lonely watchpost covered in ice and snow would never again be isolated and without reinforcements.
◇◆◇◆◇
During the long wait, two crisp and steady reflections of sunlight appeared once again from the distant snowy mountaintop, from the direction of the watchpost that had remained motionless for so long.
—It was the Northern Watchpost confirming receipt of Linbei’s confirmation of receipt.
At this moment, the entire observation platform at Linbei City erupted.
No elaborate words were needed.
Everyone understood what this return signal meant.
It was not a coincidence.
It was not a one-time flare.
It was a “back-and-forth exchange” crossing vast distances and cutting through the cold wind and snow.
This was the first time this land had ever experienced true long-distance real-time communication.
Su Muchen stood at the edge of the crowd wearing a white gauze veiled hat, remaining quiet from beginning to end.
He did not join the others in shouting.
He simply gazed silently at the streams of light traveling through the distance like sparks from the stars.
At that moment, an image from another time and space involuntarily surfaced in his mind—
Cell phones.
The Internet.
Satellite signals reaching everywhere.
Then he looked back at what stood before him.
The endless snowy mountains.
Ancient beacon towers.
The binoculars in their hands.
The meticulously polished sunlight signal mirrors.
And the people of the Northern Frontier standing before him, clad in heavy armor and struggling to endure the wind and snow.
They had no semiconductors.
No electricity.
No codes.
They had relied only on intelligence, perseverance, and their desire to survive to bridge a technological gap spanning hundreds of years, using the clumsiest yet most awe-inspiring method this era could offer.
The corners of Su Muchen’s lips suddenly curved into the faintest smile, yet his eyes inexplicably grew warm.
He gazed into the distance and murmured,
“…We really did it.”
The tense atmosphere on the observation platform finally broke.
Everyone breathed deeply in relief, followed by a burst of relieved laughter.
Qin Feng, responsible for recording the transmission data, was flushed with excitement. His wrist trembled like a sieve as his pen raced frantically across the paper.
When he presented the first recorded return message, Xia Lanshi took it and looked at it.
His brows, however, slowly furrowed.
“General Qin.”
Qin Feng was still immersed in overwhelming joy. He straightened his chest and answered loudly.
“Here!”
Xia Lanshi held the record book out before him, his voice perfectly calm, his expression seeming almost amused.
“You wrote ‘received’ as ‘收刀.’”
Qin Feng looked down.
Sure enough, written crookedly on the paper were two large characters:
收刀 — sheath the blade.
The surroundings instantly fell silent.
Qin Feng’s face went from red to white.
He was so embarrassed that he wished he could dig a hole in the ground and crawl into it.
Pei Yi, standing beside him, reached out his large hand and gave Qin Feng a heavy pat on the shoulder.
With complete seriousness, he comforted him.
“It’s fine. When it comes to fighting in the Northern Frontier, we’ll have to sheath our blades eventually anyway.”
“Pfft—”
Someone failed to hold back a laugh.
Immediately afterward, the surrounding commanders burst into laughter. The tense, grim atmosphere vanished in an instant, replaced by ease and cheerfulness.
However, technical testing was never going to proceed without setbacks.
During the third full-scale test, an accident still occurred.
Remote observation post No. 3 suddenly went silent.
It was already a full beat behind the scheduled time, yet still had not transmitted a signal.
The atmosphere on the platform suddenly tightened, and several commanders’ expressions changed.
Pei Yi raised his binoculars and said in a low voice,
“A large layer of thick cloud has drifted over. It blocked the sun.”
The greatest enemy of the Light Network had never been distance.
It was the weather.
Everyone grew tense.
If they encountered prolonged stretches of cloudy or rainy weather, wouldn’t this entire system become useless?
Xia Lanshi’s brows drew tightly together. He immediately opened the emergency protocols in his hand and was about to issue new instructions.
“Don’t panic.”
Xiao, who had been standing nearby with his arms folded and observing the entire time, spoke calmly.
There was not the slightest ripple in his voice.
Xia Lanshi paused.
“But they missed the rhythm…”
“People make mistakes, and the weather is unpredictable as well. A real system can never achieve one hundred percent error-free operation.”
Xiao’s gaze remained calm as he watched the distant mountains.
“So the rules cannot merely tell people how to proceed. They must also ensure that when people make mistakes, or when clouds block their eyes, they know how to find their way back.”
The moment he finished speaking, the thick clouds in the distance slowly dispersed.
As though realizing that something had gone wrong, the hesitant watchpost immediately adjusted the angle of its signal mirror.
A rapid and precise sequence of two-light signals pierced through the thin mist once again.
After a brief delay, the entire communication chain automatically repaired itself and reconnected.
Xiao watched the fleeting flashes of light, his tone giving away no emotion.
“Good.”
Xia Lanshi was slightly startled.
“Good?”
“Today isn’t about proving that no one will ever make a mistake.”
Xiao withdrew his gaze and turned toward the person beside him, speaking one word at a time.
“It’s about proving this—even if someone makes a mistake, even if someone misses something, even if the weather changes, the entire system can still remain alive and keep operating.”
Those words precisely captured the most fundamental principle of modern communication systems—
Fault tolerance and resilience.
The morning light finally spread completely across the towering walls of Linbei City.
Cheers rose and fell across the observation platform. The soldiers clapped one another on the shoulders and celebrated, rejoicing over this miracle worthy of being recorded in the history of the Northern Frontier.
Only Xiao Yuan did not join the crowd.
He stood alone at the highest point of the city tower, his deep gaze passing over the celebrating crowd and settling upon the endless snowy mountains to the north.
The wind disordered his long hair, black and silver interwoven like ink and frost, making his back appear lonely and heavy.
Footsteps sounded behind him.
Su Muchen had come over at some point and now stood beside him.
“What are you thinking about?” Su Muchen asked softly.
Xiao Yuan did not answer immediately.
His gaze seemed to pierce through time and space, falling upon those who had already died in the years long past.
After a long while, he finally spoke.
“Many years ago… if we had had something this convenient, perhaps so many people in the Northern Frontier would not have had to die.”
The words were spoken lightly, yet they weighed as heavily as a thousand jun.
They pressed a layer of desolation over the joy and fervor of the entire chapter.
This had never been merely a cold, mechanical system.
It was an answer purchased with the blood and bones of countless soldiers of the Northern Frontier, nameless scouts, and ordinary people who had died beneath the endless wind and snow.
Su Muchen did not offer words of comfort.
He simply stood there quietly, extended his hand, and gently touched the back of Xiao Yuan’s hand with his own.
Together, they looked into the distance.
Among the distant snowy mountains, the mirrors of one observation post after another reflected dazzling sunlight in succession beneath the morning glow.
Pale golden rays intertwined and connected, resembling a brilliant river of stars stretching across the boundless lands of the Northern Frontier.
Until, at last, the final light post on the distant horizon illuminated.
At that moment, the entire Light Network was completely lit.
Xiao Yuan’s deep gaze fixed upon that road of light.
The cold wind lifted the hem of his robes.
He spoke softly, yet every word rang with force.
“From this day onward.”
He paused and looked across the land that would never again be completely cut off by wind and snow.
“All the cities of the Northern Frontier shall hear the same command.”
“The Northern Frontier—shall have no isolated city ever again.”
Behind him, Xia Lanshi lowered his eyes and picked up his pen.
Silently and solemnly, he wrote those words onto the title page of the Northern Frontier’s first Light Network record book.