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

On the seventh day after Amu's death, Old Wei built a small altar on the south gate tower using broken bricks. Lacking incense and candles, he used pine torches for night watch. Without offerings, he placed his own rations on the altar. He pulled out a tattered account book from his pocket and placed it in the center—the pages still bore Amu's clenched fingerprints from his last moments, the bloodstains dried and gleaming a dark brown in the torchlight. He wiped his hands on his trousers, removing the ash from the granary, then stepped back and stood silently for a long time. This veteran, who had fought his way back from the Fei River, stood ramrod straight, his lips pressed into a thin line, without uttering a single word.

Shen Du stood by the battlements, took out the red knotted peace knot from his bosom, and placed it beside the account book. He turned and cast his gaze upon the silent Xianbei camp outside the city. For the past few days, he had been repeatedly studying the records about Murong Chui in the bamboo slips; he could practically recite those tiny characters from memory. Murong Chui was the first to organize his troops to retreat from the Battle of Fei River. After returning to Hebei, he remained inactive, neither openly rebelling against Qin nor continuing to pledge allegiance to Fu Jian. Murong Chui had been observing when Yao Chang raised his army north of the Wei River; he had been observing when Yao Chang besieged Chang'an. His scouts appeared several times a day on the earthen beams north of the city, glancing at the city walls before disappearing behind the horizon. Shen Du knew what Murong Chui was waiting for—for Chang'an to fall, for Fu Jian to die, for Yao Chang to be exhausted after conquering Chang'an, before he could reap the benefits. But waiting itself was an attitude. Not opposing Qin meant he still acknowledged Fu Jian's legitimacy as emperor. Not rescuing Qin meant he didn't intend to tie himself to Fu Jian's sinking ship. He was hedging his bets, his footing not on loyalty, but on self-interest. And self-interest can be manipulated.

Shen Du returned from the edge of the battlements, squatted down beside the incense table, and took out a blank bamboo slip he had brought from Hangu Pass. He used a short knife to trim the rough edges of the bamboo slip, laid it on his knees, and began to write with a pen he had borrowed from the military advisor. Old Wei squatted down beside him, holding a pine torch to light his way, and glanced at the bamboo slip out of the corner of his eye, recognizing the first few characters—"General Murong's Appreciation."

"Master Shen, are you going to write a letter to the Xianbei people?"

"right."

"Write what?"

Shen Du didn't answer, but continued writing. He knew that to send a letter from Chang'an to Murong Chui, the messenger would need to cross the Qiang blockade, bypass the Xianbei scout patrols on the northern slopes of Mount Li, and the safest route was eastward through Lantian—Lantian was mountainous, beyond the reach of the Qiang forces, and the Xianbei scouts wouldn't venture into the mountains. However, a round trip from Lantian would take at least several days, and the mountain roads were still covered in snow, potentially causing the messenger to be trapped and delayed even longer. After heading north from Lantian into the Hebei Plain, he would need a fast horse, but he had none—most of the horses in the city had already been slaughtered and eaten, and the few remaining thin horses were barely able to carry the wounded. But he still had to write. This letter had to be delivered, because it was his only chance to influence Murong Chui.

He finished writing the last character, put down his pen, and placed the bamboo slip beside the torchlight to dry the ink. Then he wrapped the bamboo slip several times with oilcloth he had taken from the spy to protect it from rain and moisture. He tucked the oilcloth-wrapped bamboo slip into his robes and reached into his robes to pull out something—Azhi's peace knot. The red string was blackened by Amu's sweat and blood, but the knot's pattern was still clearly discernible. He held the peace knot in his hand for a moment, then said to Old Wei, "Go and call Azhi here."

After Azhi went up to the city wall, Shen Du didn't immediately get to the point. He simply asked Azhi how many characters she could write and what Amu had taught her. Azhi lowered her head and said that Brother Amu had taught her to write her name and the characters posted at the granary entrance—"grain," "rice," "in," and "out." Shen Du took a new account book from his pocket and placed it in Azhi's hands, along with a charcoal pencil. He said, "This account book is for you. Amu's account book was burned, but the granary accounts must continue. Wherever Amu wrote, you should continue from there." Azhi took the account book, hugged it to her chest, and tears fell, landing on the cover, but she didn't cry out. She simply pursed her lips, lowered her head, and used the charcoal pencil to write two crooked characters on the cover—"Amu." Then she looked up, wiped her nose with her sleeve, and asked, "Master Shen, can I keep accounts for Brother Amu? Can I do anything else for him?"

Shen Du looked at her red-rimmed eyes, remained silent for a moment, then took the oilcloth bag from his arms and placed it in her hand, calling over Old Wei. He instructed Azhi to disguise herself as a refugee woman fleeing the city, mingling with the laborers who would be searching for wild vegetables outside the city early the next morning. Old Wei would lead a reliable team to meet her outside the city and escort Azhi to Lantian. Once in Lantian, Azhi would travel alone with the bamboo slips north towards Hebei, to find Murong Chui's camp. Shen Du straightened Azhi's clothes, then took out his last ration—a dry biscuit—from his pocket, broke it in half, and gave one half to Azhi and the other half to Old Wei. He told Old Wei not to take the main road, but to go around to the foot of Mount Li. Amu was gone; his sister had to be delivered safely. After escorting her to Lantian, he would hand Azhi over to a reliable guide and then return immediately.

"I'm a veteran with one foot in the grave, I'll make a profit no matter which way I go. But this young girl—" Old Wei's Adam's apple bobbed, but he didn't finish his sentence. He just stuffed the dry biscuit into his pocket and turned to call people.

After Azhi set off, Shen Du stood on the city wall, gazing eastward for a long time. Mount Li was faintly visible in the morning mist, the path at its foot half-hidden by withered grass and remnants of snow, appearing as a thin gray line from afar. Old Wei and Azhi's figures had already disappeared at the end of that gray line. He turned his head, and in the Qiang camp outside the city, the shadow of the battering ram had once again become visible in the morning light.

Yao Chang's pause in the attack ended. The Qiang phalanx began to regroup before dawn, with the battering ram pushed to the front of the formation. The scouts sent out by Commandant Zhu returned to report that the wooden frame of the battering ram had been reinforced, the iron head had been replaced, and the ram body was thicker than before. But this time, Yao Chang's troop deployment was different—he placed his main force at the west gate, not the north gate. Shen Du, behind the crenellations, repeatedly confirmed with his binoculars that it was indeed the west gate. He put down his binoculars and lightly tapped the bricks of the crenellations twice with his finger. Since the siege began, Yao Chang's main attack directions had always been the south and north gates—the sluice gate at the south gate had cracks, and the city wall at the north gate was relatively low, making these two directions the easiest to breach. Outside the west gate was the Wei River; although the river was frozen, the banks were muddy, which was not conducive to the deployment of siege equipment. Yao Chang's sudden shift of his main force to the west gate could only mean one thing: he knew that the cracks in the sluice gate had reached their limit and deliberately diverted the defenders' attention, with the main attack direction still the south gate. Ximen's attack was a feint.

"Captain Zhu," Shen Du turned around, "Leave half the troops at the North Gate and half at the South Gate, and the fewest at the East Gate. You go to the West Gate personally, taking all the oil and half of the archers. The area outside the West Gate is muddy and difficult to traverse, making it hard to deploy the battering rams. Their ladders will reach the base of the wall before the battering rams—focus on attacking the ladders. Pour the oil onto the muddy ground outside the city wall; once lit, the mud will turn into a fire pit, which is more effective than directly pouring oil on the ladders. Set the fire as soon as you hear the gong from the city tower; don't pour the oil beforehand."

"Doesn't Ximen need reinforcements?" Captain Zhu asked.

"No need. The attack on the west gate is a feint; Yao Chang's main force is still at the south gate. Concentrate all the ramming stones and sandbags at the south gate—the heavy gate can still hold for a while, but the walls on both sides of the gate are already loose. If cracks appear at the base of the wall, fill them with sandbags. If there aren't enough sandbags, use the broken bricks and tiles that have been dismantled. Also, move all the extra crossbows from the east wall to the south gate and re-install firing ports inside the gate. Assign a skilled archer to each crossbow, specifically to shoot down the infantrymen using push hammers."

Commander Zhu accepted the order and quickly walked down the city wall. Shen Du slammed the iron spear shaft against the city bricks and raised his voice to the guards on the city wall, saying that the cracks in the Thousand-Jin Gate must be temporarily reinforced before dawn tomorrow, and that the blacksmith should melt down all the molten iron and make iron hoops.

"What if we don't have enough iron?" Old Wei's deputy asked.

"Take down the collapsed barracks' iron parts, rotten weapon racks, broken chains, broken pots and pans—melt everything that can be melted."

"Master Shen, there are only two blacksmiths left in town. They need charcoal to smelt iron, and the charcoal is almost gone—"

"For the parts that can't be melted in time, use wet sandbags and thick ropes to hold them in place. If there aren't enough iron hoops, use ropes to tighten the gaps first."

"Will the rope be able to tighten?"

"We have to tighten it, even if we can't. I want to see that crack closed by tonight."

The people on the city wall dispersed to their respective tasks. Shen Du turned around and looked out of the city again—the Qiang phalanx was slowly advancing, the battering ram drawing ever closer to the south gate. Further away, at the foot of Mount Li, a thin gray line disappeared into the morning mist. He knew Azhi was walking that road, a small, thin girl who had learned to write the characters for "Amu" while carrying an account book, crossing the Qiang blockade to deliver the letter that had swayed Murong Chui. He didn't know if he would ever see her return. But he knew that someone had continued writing Amu's account book—that was enough.