In this realistic war game, only I understand the course of the battle.

Heading west from Yaoshan, the road gradually became easier. After leaving Yaoguan Pass, the mountain path began to descend gently, the gravel slopes turning into a dirt road, and the snow on both sides thinned. By the fifth day, scattered farmland began to appear by the roadside—left barren in winter, with withered wheat stubble peeking out from the remaining snow on the ridges, resembling a layer of grayish-yellow stubble. The appearance of farmland meant that human habitation was not far off. But Shen Du noticed a detail: the ridges of these farmlands were neatly constructed, and the irrigation ditches were also well-organized, not the crooked ditches dug by ordinary farmers, but proper irrigation canals lined with stones. This was a military settlement. Near Hangu Pass, there were Qin army settlements, where soldiers guarded the pass while also cultivating the land; this field must have been the ration field for the garrison inside the pass. But there was no one in the field, the water in the canals had dried up, and the few bundles of straw piled on the ridges were scattered by the wind.

"Something's not right." Shen Du stopped and squatted by the roadside, pinching the dry soil in the ditch with his fingers. The soil had been flooded last autumn—the dried silt still bore the fine lines left by the water—but after the autumn harvest, this farmland was completely abandoned. Even if the garrison was conscripted south, they should have left a few old and weak people to watch over the fields. Unless even the old and weak were taken away.

The group walked along the edge of the garrison for about half an hour until a fortified pass came into view. It wasn't an ancient pass like Xiaoguan, abandoned for over a thousand years—it was a still-functioning military fortress. The pass wasn't large; its walls were constructed of a mixture of bluestone and rammed earth, connecting to the ruins of the Great Wall on the mountain ridge on the east and west sides. The gate faced the official road to the east. Black Qin army flags still flew on the battlements, but the flags were faded by wind and rain, some torn into strips that fluttered weakly in the wind. The gate was wide open, the door panel askew to one side, and the inside of the gate was covered with a layer of withered leaves and sand blown in from outside. There were no sentries on the walls, no smoke from cooking fires, no neighing of warhorses, not even the barking of dogs. The entire pass was as silent as a dry well.

"Hangu Pass." Zhou Jing stood in front of the pass, leaning on a wooden cane, his voice hoarse and low. The last time he stood here was when he was on a military expedition. Banners fluttered atop the pass, soldiers were taking roll call, and long lines of grain transport convoys stretched from the city gate. Now the pass still stands, but the guards are gone.

Shen Du ordered his men to wait outside the fortress while he led Lao Wei and Zhou Jing inside to scout. The stone slabs of the gate were uneven, worn smooth by horses' hooves and wheels, with withered weeds growing in the cracks. There were knife marks on the walls on either side of the gate—not old marks, the cuts were fresh, without rust. Shen Du ran his finger along the edge of the knife marks; the iron oxidation was very slight, no more than a month old. Passing through the gate and into the fortress, the scene before him confirmed his worst fears—the soldiers' barracks were empty, the doors wide open, the bedding gone, but the iron pots in the kitchen were still on the stoves, the ashes scattered everywhere by the wind. The armory door had been forcibly pried open, revealing only a few broken spears and a cracked shield. The granary door had also been pried open; it was empty, with only a few crushed millet grains scattered in a corner. It wasn't a retreat by the defending troops—a retreat wouldn't leave behind every grain of food, nor would they only keep the broken weapons. This was either a rout of defeated soldiers passing through, or the defending troops themselves mutinying, looting all the food and weapons, and then running away.

Shen Du squatted at the entrance of the granary, picked up a grain of millet with his finger, and chewed it. The millet was dry and hadn't gone moldy yet; it couldn't have been looted in more than a month. He stood up, his gaze sweeping across the empty streets of the pass, his mind racing with calculations—it had been almost two months since the defeat at Fei River. News of the defeat would only take a dozen days to travel from Fei River to Hangu Pass. What would the defending troops do upon hearing of the crushing defeat at the front and the annihilation of a million-strong army? The answer was—they would run. Or worse, they would loot first, and then run. No officers would stop them, because the officers were all on the riverbank south of Fei River. There were no military orders, because the messengers had also been scattered in the rout. From that moment on, the gateway to Guanzhong was undefended.

"Let's go up to the city wall and take a look," Shen Du said.

The scene on the city wall was even more horrifying. The cannons on the crenellations were still there, but their muzzles had been smashed askew. The crossbows on the city wall had been dismantled and thrown to the ground, their bowstrings cut, and their arms broken in two. The large iron pot used for boiling molten gold lay overturned at the corner of the city wall, its bottom facing upwards, covered in rust. Someone had deliberately sabotaged these defenses—not the enemy, for an enemy breaching the pass would only destroy the gates and walls, not specifically climb the city wall to cut the bowstrings of every single crossbow. Only their own people had cut the bowstrings. They didn't want this pass to fall into the hands of anyone else.

Shen Du stood atop the city wall, gazing westward. To the west lay the Guanzhong Plain. Under the thin winter sun, the Guanzhong Plain stretched out in the distance, the Wei River winding like a silver ribbon across the vast land, its banks shrouded in a hazy mist. This was once the homeland of the Qin state, the foundation upon which Fu Jian had unified the north. Now, sparse smoke rose from the chimneys, the fields lay barren, defeated soldiers roamed the countryside, and tribal leaders were secretly sharpening their swords. Hangu Pass was empty; the gates of Guanzhong were wide open.

"Close the city gates," Shen Du said, turning to Old Wei. Old Wei was taken aback. "Close them? We're not leaving?"

"We'll spend the night here." Shen Du walked down the city wall, his steps quick but steady. "The gate can be locked from the inside. There are crenellations on the city wall to keep out the wind. The granary is empty, but the warehouses can keep out the snow. This is a military fortress, much safer than the wilderness outside. We'll continue our journey at dawn tomorrow."

That night, the troops settled into the barracks at Hangu Pass. Although the beds had been emptied, the ground was rammed earth, and the dry grass and tent cloth provided a much better experience than sleeping in the freezing cold. The stove in the kitchen was still usable, so Zhou Jing and his men cleaned it thoroughly and cooked a pot of porridge using aged millet brought from Xiaoguan and a usable iron pot from inside the pass. After the porridge boiled, he sprinkled in a handful of dried wild vegetables he had gathered from the fields outside the pass—the kind of grass he had brought from the refugee camp that was resistant to freezing and sunburn. It tasted extremely bitter, but it could prevent scurvy and provided a little extra food. The refugee soldiers squatted around the iron pot in the barracks, using their helmets as bowls, and each received a bowl of hot porridge. After finishing their bowls, some soldiers turned their helmets over and licked the remaining rice water off the inside.

Shen Du didn't stay in the barracks. He walked alone along the city wall, carrying an oil lamp he'd salvaged from the ruins. The crenellations cast neat shadows in the moonlight, their edges sharp and cold. He reached the northwest corner of the wall, placed the lamp on a crenellation, and pulled out the Southern Army command flag he'd torn from Baojia Camp. The flag was covered in markings—Dezhou, Jinan, Dongchang, Jiahe, Gaocheng, Qimei Mountain, Lingbi, Yangzhou, Nanjing, Hami, Jiaozhi, Jiangxi, and finally, the Fei River. He carved a new mark on the flag with his dagger. This one marked Hangu Pass. He spread the flag out on the crenellation; the moonlight shone on the dense markings, each one a city, each one a stretch of road. From the Baigou River to Nanjing, from Juyong Pass to Hami, from Jiaozhi to Jiangxi, from the Fei River to Hangu Pass—the distance he has traveled in this game is longer than any line on any map. But he knows that in this instance, his journey is far from over.

The next morning, the group set off from Hangu Pass, heading west along the official road into the Guanzhong Plain. Vast fields lay abandoned on both sides of the road, and the villages they occasionally passed were mostly deserted. Some villages had houses burned down to ruins, while others, though the houses were intact, had their doors and windows locked. Hearing footsteps on the road, a few wary eyes would peek through the cracks in the doors before quickly retreating. By afternoon, they finally encountered living people—a caravan coming from the direction of Guanzhong, leading seven or eight mules laden with goods, including salt and cloth. Several merchants, heads bowed, rode around a dilapidated supply wagon. Seeing Shen Du leading a group of about a hundred people towards them, they quickly moved to the side of the road, raising their hands high to indicate they were not bandits.

Shen Du walked up to the caravan and cupped his hands in greeting to the elderly merchant at the head of the group: "We come from Huaibei and are on our way to Chang'an. Is the road safe?"

The old merchant sized him up, then glanced at the mud-covered, tattered soldiers behind him. His wariness eased slightly, but his tone remained cautious: "Which tribe are you from? Xianbei? Qiang?"

"The Guanzhong Army," Shen Du said. "They came back from the south bank of the Fei River."

The old merchant paused for a moment, then shook his head, lowering his voice slightly: "Be careful on the road to Chang'an. There are Xianbei cavalry stationed ahead in Weinan. They claim to be guarding Guanzhong on Fu Jian's orders, but they capture any fleeing soldiers they see, incorporating them into their own ranks, and killing those who disobey. Our caravan came from the north, adding over a hundred li to avoid them." Xianbei cavalry. Murong Chui was a Xianbei; he was the first to organize a retreat at the Battle of Fei River, and now back in Guanzhong, he's become the one maintaining the borders. Fu Jian's prestige plummeted after the disastrous defeat at Fei River, and the tribal leaders had begun to act independently.

"Thank you." Shen Du cupped his hands in thanks and led the group onward. After walking a few miles, Zhou Jing caught up from behind and whispered, "We'll bypass the Xianbei cavalry in Weinan."

"Go around."

They took a long detour westward from Weinan, avoiding the main roads guarded by Xianbei cavalry, but this added two days to their journey through the mountains. More corpses appeared sporadically along the mountain paths—desperate soldiers, civilians, and even several monks in robes lying by the roadside, their packs turned upside down. Wild dogs and crows discovered the bodies before the people, some already pecked beyond recognition. The wind and snow were lessening, but the air was thicker with the stench of blood. Crossing this mountain path, in a sheltered valley, they encountered another group of defeated soldiers returning from the Fei River. This group numbered only a dozen or so, even worse off than Shen Du's group—they were unarmed, their straw sandals lost, their toes blackened with frostbite, looking like a group of living dead crawling out of a tomb. The centurion, upon seeing Shen Du, knelt on the ground, his chapped lips trembling for a long time before finally uttering only two words: "Chang'an—"

Shen Du helped him up and had Old Wei distribute the remaining porridge to them. The centurion, holding the bowl, trembled so much that the porridge spilled all over the ground. He said they had fled back from the direction of the Ying River, pursued all the way by Xianbei cavalry, and their original force of seventy or eighty men had been reduced to only a dozen or so. He asked Shen Du how far Chang'an was, whether there were any troops still stationed in Chang'an, and whether they could still get home from Chang'an.

"How far is Chang'an?" the centurion asked again, his voice trembling like a reed in the wind.

Shen Du stood up and gazed at the western horizon. There, a thin black line stretched out—the city wall of Chang'an. This wall, which had once protected the ancient capital of Qin and Han, might not even hold out until spring. He looked down at the centurion and said, "It's not far. Come with us."

The column continued westward. The walls of Chang'an drew ever closer. Shen Du led the way, the bamboo slips in his arms soaked with sweat and dried by the mountain wind; their edges were beginning to wear, but the writing on them remained clearly legible. The mountain wind blew from behind, making the tattered Qin army banners stand straight.