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

The passes of Liang County grew smaller and smaller on the horizon, eventually becoming a black dot on the gray-yellow horizon. Shen Du glanced back; Commandant Zhu was still standing on the pass wall, looking in their direction, the Qin army flag that had been re-hung behind him fluttering slightly in the thin winter sun. He didn't ask Commandant Zhu if he regretted it—regret was something one could only think about after surviving; they didn't have that right now.

West of Liang County, the terrain begins to rise and fall. The Huaihe Plain ends here, replaced by a series of low hills, crisscrossed by loess gullies, everything painted a grayish-yellow in winter. The road becomes a narrow, winding path, weaving through the gullies, the narrowest point only wide enough for one person to pass sideways. Zhou Jing said this was a grain transport road opened up by the Qin army during their westward expedition, but it hadn't been repaired for decades. The road surface was riddled with potholes from rain, and some sections had even collapsed into cliffs.

"Mount Xiao is just ahead." Zhou Jing stood on a ridge, pointing west with a wooden stick he had been sharpening for days. Shen Du looked in the direction he was pointing—a gray-blue mountain range rose on the horizon, completely different from the low loess hills of the Huaihe Plain. It was a real mountain, its ridgeline clear and stark in the thin winter sun, like a city wall cleaved by a sword and axe, stretching across the sky and earth. "Beyond Mount Xiao is Hangu Pass, and beyond Hangu Pass is Guanzhong."

When the words "Guanzhong" spread through the ranks, it was like a pebble thrown into stagnant water. Old Wei, walking at the front, glanced back; Amu, in the middle, looked westward for a long time; even the wounded soldiers at the back helped each other quicken their pace. But Zhou Jing didn't let the group continue. He stood on the earthen ridge, gazing at the distant mountain range for a long time, his expression no longer as relaxed as it had been on the ferry.

"Crossing Mount Xiao in winter is difficult," he said. Mount Xiao is no ordinary mountain. It is the eastern gateway to Qin, forming a strategic point with Hangu Pass to the east and west. Beyond Mount Xiao lies the Guanzhong Plain, but crossing it is a deadly undertaking—the mountain path is steep, and in winter, heavy snow closes the mountain, with snow reaching waist-deep in some places, and the wind at the wind gaps can blow a person off a cliff. He struggled forward through the snow, stopping every few steps to catch his breath.

But Shen Du had no choice but to stop. The troops had run out of food. The last bit of millet they'd brought from Old He's boat after crossing the Ying River had also been exhausted the day before yesterday. The wounded soldiers' wounds were healing more slowly in the cold; Amu's fever had subsided, but he was so weak he was breathless after just a few steps; Old Wei, wrapped in a tattered sack, could still manage, but many more were pushing their last ounce of strength to the limit. They replenished their supplies in Liang County, but it was far from enough. Running out of food in the mountains meant death.

"Let's go." Shen Du planted the iron spear shaft into the frozen ground and took his first step over the mountain. The group followed behind him, climbing up the slope. The path was made of gravel and frozen soil, crunching underfoot. The bushes on both sides of the path were withered, their bare branches trembling in the cold wind like countless dry, thin hands.

Mount Xiao, straddling the Qin region and the Central Plains, is a strategically vital location that has been contested by military strategists since ancient times. The Battle of Xiao between Qin and Jin during the Spring and Autumn Period took place here, where the Jin army ambushed and annihilated the Qin army, capturing their commander, Meng Mingshi, leaving behind the enduring tragedy of the Battle of Xiao. Later, the Qin state built Hangu Pass at the western end of Mount Xiao, thus securing the eastern gateway to Guanzhong. However, that was during the Warring States period—the present-day Hangu Pass has been abandoned for many years, its garrison having been mobilized south by Fu Jian, leaving Guanzhong vulnerable. The pass, though still standing, is unguarded. Shen Du had recounted these historical events countless times in military academy classes, but walking along the mountain path now, he truly felt the oppressive atmosphere—not because of the history, but because of the cold. The mountain wind swept into the valley from the northwest, pelting down with snow and gravel. Icefalls cascaded down the cliff faces on both sides of the mountain road, and withered ancient pines grew horizontally from the crevices, their branches encased in ice, resembling transparent sticks.

Zhou Jing walked beside Shen Du, tapping the rocks by the roadside with a stick every so often to listen to the sound—he said there were underground rivers in the mountains, and tapping the rocks would reveal hollows, allowing him to avoid stepping into sinkholes. His ears were very sharp; he could distinguish between solid rock and hollows with a single tap. Once, he tapped a seemingly ordinary patch of gravel, frowned, squatted down, and listened for a long time. Then he stood up and led the group around a large bend. Looking back afterward, the gravel had been blown away by the mountain winds, revealing dark, bottomless cracks beneath. He was from Yongzhou and had crossed the Xiaoshan Mountains several times with the army in his youth. He said that crossing the Xiaoshan Mountains in summer was not dangerous; although the mountain paths were steep, the weather was not cold, and they could pick wild fruits by the roadside to eat. Crossing the Xiaoshan Mountains in winter was a life-or-death struggle—every section of the mountain path required finding a way under the snow, and every step could lead to slipping on black ice and falling off a cliff.

The next afternoon, they reached the middle section of Yaoshan Mountain. Here lay an abandoned ancient plank road, built by the Qin state during the Warring States period. Wooden stakes were driven into the rock face, and planks were laid on top, suspended above a bottomless abyss. The plank road had been abandoned for decades; the stakes were rotten or broken, and the remaining planks were covered with a thick layer of ice and snow. But if they didn't take the plank road, they would have to detour through the narrow, winding paths on the southern slope, which would take several more days. For this starving group, several more days of travel meant more deaths. Shen Du stood at the entrance of the plank road and glanced down—it was bottomless, with only grayish-white mist swirling at the bottom of the valley. The wind rushed up from the canyon, making the remaining planks on the plank road creak and groan. A few rotten planks were lifted by the wind, tumbled in the air, and fell into the abyss.

"One person at a time," Shen Du said, turning to the group behind him. His voice wasn't loud, but every word was clearly heard in the canyon wind. "Step on the crossbeams of the walkway, not the planks—the planks are rotten. The crossbeams are whole logs driven into the rock face; they can still bear weight. Hold onto the iron chains on the rock face, and don't look down." He paused, looking at each person's face. "Those who can walk, walk on your own. Those who can't—Old Wei, you carry them."

Old Wei nodded, saying nothing more, but tightened the sack around his body and squatted down in front of Amu. Amu tried to refuse, but Old Wei pulled him onto his back, supporting him steadily like a sack of grain. Shen Du was the first to step onto the plank road. The iron chains were icy cold, and gripping them felt like they were glued to his palms. He held the iron spear shaft across his waist, alternating his feet on the crossbeams. The old wound on his left leg throbbed in the cold wind, but he didn't stop to rub it. He walked forward step by step, making sure each step was firm before moving on to the next. After completing the first section of the plank road, he turned back and gave a safe signal to the people behind him. Then came Zhou Jing, then Amu was carried across by Old Wei, and then the remaining defeated soldiers crossed this most dangerous part of the mountain path one by one on the rotten planks. When the last Xianbei soldier was halfway across, a plank under his foot suddenly broke, and his body plummeted for a moment—but his hands clung tightly to the iron chains, and he dangled in mid-air, swaying. Shen Du and Lao Wei rushed back onto the plank road at the same time, each grabbing one of his arms and pulling him up. The Xianbei soldier sat in the snow, panting for a while before catching his breath. Zhou Jing squatted down beside him and checked his arms and ribs to make sure there were no fractures.

On the third day, they reached the depths of the Yao Mountains. The snow had deepened, reaching knee-deep, and they had to use the shafts of their spears to probe the path with each step. In the afternoon, the group crossed a ridge, and suddenly the view opened up before them—ahead lay a mountain basin, in which stood an abandoned ancient fortress. The fortress walls were built of bluestone slabs, without mortar to join the stones; they held together entirely by their own weight—an old technique from the Warring States period, later used by Qin Shi Huang when building the Great Wall. The walls were covered in withered moss, and several sections of the crenellations had collapsed. Above the gate were two large characters, powerfully written, still faintly discernible despite the erosion from the wind and sand—"Yao Pass."

The Battle of Yao, between Qin and Jin during the Spring and Autumn Period, took place here. The Qin army was completely annihilated by the Jin army, and Meng Mingshi was captured. That ambush shattered Duke Mu of Qin's ambition to advance eastward into the Central Plains. Later, the Qin improved the defenses of Hangu Pass, truly securing Guanzhong. Yao Pass was abandoned, leaving only this empty fortress nestled deep in the mountains, weathered by the winds for over a thousand years. Shen Du stood at the gate of Yao Pass, touching the cold bluestone slabs of the city wall. There were knife marks on the stone surface—not fresh, but left from over a thousand years ago. When he lectured on ancient warfare at the military academy, he dedicated a chapter to the terrain analysis of the Battle of Yao, and the slides he used at the time included a photograph of this fortress. But photographs and standing here in person are completely different things. The wind here is colder than in the photographs, the stones here are more real than in the photographs, and beneath the snow lies not soil, but the bones of those who died in battle over a thousand years ago.

"We'll spend the night in the fortified city," Shen Du said to the group as he turned around.

Although the fortress was dilapidated, the stone walls on all four sides were still intact, and the gate openings could block the mountain winds. Although most of the old barracks inside the fortress had collapsed, a few houses still had intact frames that could shelter from the snow. Zhou Jing ordered a few soldiers to clear a space inside the fortress to start a fire, and then led others to gather firewood nearby. He walked to a barracks ruin, squatted down, and used a dagger to pry open a few rubble stones at the base of the stone wall, revealing a hidden hole underneath. "Come and see," he beckoned Shen Du over, and used his hands to dig away the soil at the entrance of the hole. Inside were several pottery jars, their mouths sealed with wax. He moved the jars out and opened them—they contained millet. The Qin army's military rations stored at Yaoguan were sealed with wax to prevent moisture and hidden in cellars. More than a thousand years had passed, and the millet had dried like gravel, but it had not yet completely rotted.

"How did you know there was grain hidden here?" Shen Du asked.

"I like to study these old things, like the Qin army's cellars. Besides, veterans who have lived in Guanzhong for a long time have all heard a little about them." Zhou Jing poured the millet from the earthenware jar into the iron pot. The dried millet had been boiled in boiling water for a long time before it barely softened, and the resulting porridge had a musty smell, but it was edible. Shen Du distributed the porridge to everyone and told Zhou Jing to take all the remaining jars of millet with him—enough for the team to eat for three days, and they had to get out of Xiaoshan within three days.

At night, the troops huddled around the campfire in the gate of the fortified city. The stone walls blocked the mountain winds, and the warmth of the campfire baked a thin layer of moisture onto the moss on the walls. Amu leaned against the wall, slowly wiping the tip of his spear with the corner of his robe. Shen Du sat by the campfire, rereading the bamboo slips in his arms. His fingers traced the slips, his gaze lingering on the last few scrolls containing records of conflicts between the various tribes. Murong Chui's Xianbei cavalry were the first to withdraw from the Fei River battlefield, indicating they were well-prepared. Yao Chang's Qiang infantry followed closely behind. What would these men do after returning to Guanzhong? Fu Jian suffered a crushing defeat at Fei River, his prestige shattered. Would the tribal leaders still obey his commands? The Xianbei, Qiang, and Xiongnu—these tribal leaders were probably no longer concerned with the survival of the Former Qin, but rather with their own territories and armies. After the collapse of the Former Qin, the north would once again fall into division. Fu Jian would be killed by Yao Chang, Murong Chui would establish the Later Yan in Hebei, and Yao Chang would establish the Later Qin in Guanzhong. Shen Du knew these historical trends, but he had no intention of changing them. He was not Fu Jian's strategist, nor a loyal subject of the Former Qin; he was merely a centurion leading his remaining troops home. But in chaotic times, this intelligence would become a form of hard currency—regardless of who possessed it, those who had intelligence always had a better chance of survival than those who did not.

On the fourth day, they crossed the last ridge of Xiaoshan Mountain. The descent was more dangerous than the ascent—the snow-covered, rocky slope was slippery. Old Wei, carrying a wounded soldier, slipped and slid down the slope, landing several meters in the snow. The wounded soldier rolled off his back and landed in a snowdrift. Both were startled. Old Wei got up from the snow, first checking if the wounded soldier was injured. After confirming that the soldier had only choked on the snow, he brushed the snow off himself and sat down to catch his breath. After descending, the path gradually leveled out, and the snow thinned. Dry wild berries, still hanging from the branches, began to appear on the bushes on both sides of the path in sheltered spots. Although there weren't many, there were enough for everyone to share. Shen Du had the team rest for a while on a flat riverbank, and Zhou Jing cooked the last bit of millet into a final pot of porridge and distributed it.

Shen Du stood on the riverbank, listening to the sound of the water, when he suddenly noticed movement in the bushes downstream—not from the wind, but from people. He gestured for the group to be quiet, and then, leading Lao Wei and two young soldiers, he cautiously made his way downstream along the riverbank. When he reached a patch of withered reeds, he parted them, and his pupils contracted sharply. Dozens of corpses lay scattered on the riverbank downstream, all dressed in Qin army uniforms. Judging from their condition, they hadn't starved to death—the wounds were still fresh, and the blood hadn't been completely covered by the snow. Some had their necks severed, some had been stabbed in the chest, and several had been shot through the back with arrows. Shen Du crouched down and turned over a corpse, glancing at the wound. The cut was straight and clean, made with a standard military sword, not a bandit's machete. The arrow shaft was engraved with markings—it was an arrow from the Qin army. He stood up and tossed the arrow shaft to Zhou Jing, who glanced at the inscription and remained silent for a long time.

"They're not bandits. They're our own people." Zhou Jing turned the arrow shaft over to look at the inscription on the back. "This is an arrow used by the Xianbei. Look at the fletching—the Qiang people use eagle feathers, the Xianbei use goose feathers. This one uses goose feathers." He threw the arrow shaft on the ground and looked up at the snow-shrouded mountain road to the west. To the west was Hangu Pass, and west of Hangu Pass was Guanzhong. When he left last time, everything was fine, but now, before the defeated soldiers had even dispersed, their own people had started killing each other.

Shen Du gazed ahead, knowing that beyond this mountain lay Hangu Pass, and beyond Hangu Pass lay Guanzhong. But the Guanzhong beyond the mountain was no longer the Guanzhong they had set out from. Chaos never begins under one banner, nor ends under another—it begins long ago in the heart of every swordsman.