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

July of the 22nd year of the Yongle reign, Yumu River.

Summer on the grasslands is much shorter than in Beijing. The July sun is still scorching, but the wind already carries a chill. Dry winds from Siberia, carrying sand and grass seeds, sweep across the surface of the Luqu River, rustling the birch trees along its banks. Zhu Di lies in his imperial tent, outside which stands the 60,000-strong army of the Northern Expedition; inside are only a few eunuchs and the accompanying imperial physicians. The candlelight flickers in the wind seeping through the tent flaps, and his breathing rises and falls with the flickering flame.

He set out from Beijing in April. This was his fifth and final personal campaign. The Tatar leader Arughtai had again amassed his forces on the grasslands the previous winter, boasting of his intention to move south to graze his horses. Zhu Di waited all winter, and as soon as the snow melted on the grasslands, he immediately led 60,000 cavalrymen out of the Great Wall, pursuing them along the Luqu River all the way to the Onon River, and then from the Onon River to the Tula River. But this time, Arughtai had learned his lesson—he avoided direct confrontation with Zhu Di, leading his troops in circles across the grasslands. When the Yan army pursued him to the east, he would retreat to the west, and vice versa. Zhu Di pursued him across the grasslands all spring, but never found Arughtai's main force. By July, his army was running low on supplies and his soldiers were exhausted, forcing him to order a retreat. He collapsed at Yumu River.

It wasn't an arrow wound, nor a knife wound; it was exhaustion. At sixty-five, his body couldn't withstand months of living outdoors on the grasslands. The imperial physician said it was "illness caused by overwork"—in plain terms, he was too tired, so tired that his internal organs were completely drained.

When Zhu Di opened his eyes, the setting sun was filtering through the gaps in the birch forest, casting a dark golden glow on his face. His lips were chapped and pale, his cheeks had sunken, and his cheekbones were prominently displayed. Only his eyes remained as bright as they had been on the embankment of the Jiahe River years before. The grassland outside the tent was eerily quiet, unlike a battlefield. Occasionally, the snorting of warhorses and the low murmurs of soldiers were carried in by the wind, mingling with the sound of the Luqu River. He suddenly remembered the most comfortable place he had ever been in his life. It wasn't the Fengtian Hall in Nanjing, nor the Forbidden City in Beijing, but the drafty little study on the west side of the Prince of Yan's residence in Beiping. There was no underfloor heating or incense there, and in winter it was so cold that one had to breathe on it to warm the ink before grinding it. But in that study, he had drawn a strategic map from Beiping to Nanjing, and before the battle at Baigou River even began, he had already mentally reconstructed the entire empire from beginning to end.

"Send word..." His voice was very soft, as soft as the wind outside the tent.

The eunuch knelt before the bed. "Your Majesty."

"Summon Yang Rong, Jin Youzi, Zhang Fu, and Wang Tong." He called out the names one by one, his voice weak, but the order was clear, with those of higher rank listed first. The eunuch quickly withdrew from the tent, and the twilight of the grassland rushed in the instant the tent flap was lifted. Zhu Di closed his eyes, his mind still processing military affairs, but very slowly, so slowly that he could no longer distinguish between memories and reality.

Almost simultaneously, Shen Du stood on the beacon tower outside Xuanfu City, holding a newly delivered military report. The report, from the Ministry of War, contained only one line: "His Majesty passed away at Yumu River." Upon seeing this, his fingers involuntarily tightened, and the charcoal lead broke on the paper. He didn't speak, simply folding the report and tucking it into his robes, then looked up towards the grasslands. The wind on the grasslands was the same as yesterday, dry and chilly, blowing all the way from Siberia, across the Onon River, the Luqu River, the Tula River, Yumu River, Xuanfu, Juyong Pass, and all the way to Beijing. But the vassal king who led 60,000 cavalry in pursuit of the Tatars was no longer on this grassland.

Old Zhao was squatting under the beacon tower, shoeing a newly bred mule, a pipe dangling from his mouth. Seeing Shen Du's expression, the pipe slipped from his mouth and fell to the ground. "Master Li, what's wrong?"

"His Majesty has passed away," Shen Du said. The four words were spoken softly, but to Zhao Laoliu, they sounded like a blow to the head. He squatted on the ground, stunned for a long while, then slowly stood up, picked up his pipe and clutched it in his hand, not putting it back in his mouth. He remembered how Zhu Di had personally placed the silver medal into Shen Du's hand beneath the walls of Dezhou; he remembered how, after the defeat at Dongchang, Zhu Di sat alone in a cave dwelling, gazing south, refusing to listen to anyone's advice; he remembered how, on the night of the retreat from Qimei Mountain, Zhu Di stood on the north bank of the Huai River, his lips moving as rockets pierced the night sky, as if he were saying something. That man was gone now.

"Mr. Li, what should we do?"

"Return to Beijing." Shen Du took out the military newspaper again and read it once more. The handwriting on the newspaper was neat and restrained, but he knew the weight behind this letter—an era had ended.

When Shen Du returned to Beijing, Zhu Di's coffin had already been transported back to the capital from Yumu River. White banners hung everywhere at Desheng Gate, and willow branches along the moat rustled in the autumn wind, falling into the water and onto the heads of the densely packed kneeling people on the riverbank. He had ridden for several days from the northern frontier to Beijing, arriving just in time for the final day of the late emperor's burial at Changling Mausoleum on Tianshou Mountain. He dismounted outside Desheng Gate and walked through the streets lined with kneeling people until he reached the foot of the Imperial City. He did not enter the Imperial City. Knowing that a fourth-rank military officer was not qualified to enter the palace to mourn, he found a spot on Chang'an Street where he could see the glazed tile roof of the Fengtian Hall, adjusted his official hat and robes, faced the direction of Changling Mausoleum, knelt down, and kowtowed three times.

That night, he sat alone under an old locust tree in the family quarters of the fallen soldiers of the Jingnan Rebellion in the west of the city, spreading the Southern Army command flag he had torn down from Baojia Camp on his lap. The flag was covered with markings—Dezhou, Jinan, Dongchang, Jiahe, Gaocheng, Qimeishan, Lingbi, Yangzhou, Nanjing, Hami, Jiaozhi, Jiangxi. Each marking represented a city, and each marking represented someone on the list of the dead. He then used his dagger to carve a new mark on the flag. This one had no name. He folded the flag and tucked it into his bosom, drawing the horizontal sword from his waist—not the broadsword made of meteorite iron, but the goose-feather sword he had carried with him before breaking off a locust branch to whip Zhang Heng at the Baojia Camp drill ground. The blade still bore the nicks from the Baigou River, the nicks inlaid with indelible dark marks—blood, mud, everything that could not be wiped away from the battlefield. He lowered his head, resting his forehead on the hilt of the sword. The moonlight shone on his back, stretching his shadow long.

According to regulations, the Yongle Emperor's funeral only lasted three days. Crown Prince Zhu Gaochi ascended the throne before the coffin, changing the era name to Hongxi. After his ascension, the new emperor accomplished several significant things—he exonerated former officials of the Jianwen Emperor, such as Fang Xiaoru, halted large-scale voyages to the Western Ocean, reduced taxes, and recalled border troops for rest and recuperation. However, Shen Du did not live to see the spring of the Hongxi era. He fell ill. After returning from the northern frontier, he began to cough. At first, it was just a dry cough, which he didn't take seriously—after two months of exposure to sandstorms on the grasslands, coughing was common. But the cough persisted, from autumn to winter, from a dry cough to coughing up phlegm, which began to contain blood. The army doctor examined him and said it was due to old injuries and overwork, coupled with years of exposure to cold and dampness, which had damaged his lungs. Several doses of medicine were prescribed, but there was no improvement. Zhao Laoliu, in desperation, summoned all the renowned doctors he could find in Beijing. Each doctor shook their head, saying essentially the same thing—"Overwork has led to illness, old injuries have penetrated to the bone, and the lungs are damaged."

Su Wanqing came every day. She was now a fifth-rank official in the Jiangxi Provincial Department of Revenue, responsible for calculating the grain tax for military farms during the day and going directly to Shen Du's residence after her shift. She tried various remedies: plasters prescribed by an old doctor from Shandong, decoctions from the Imperial Hospital, and folk remedies like steamed pears and honey radish juice, delivering them one by one to his bedside. Sometimes they would provide some relief, but other times he coughed so much that he couldn't sleep all night. She would sit at her desk in the outer room, reviewing official documents from the Ministry of Revenue while listening to the sounds coming from the inner room. Every night, Zhao Laoliu would squat in the courtyard smoking his pipe, the embers flickering. Gu Zhang would also come after his shift at the Ministry of War, sitting by Shen Du's bedside and explaining the progress of the border surveying in the northern frontier—the young surveyors had already taken over most of the fieldwork, the underground ditches at Juyong Pass were being dredged every year before and after the rainy season, and the newly added outposts north of Xuanfu were cooperating well with Batu's cavalry. Shen Du listened attentively, occasionally adding a few comments with his pen, but he had to stop and rest after saying a few words, his energy was clearly not as good as before.

In the spring of the first year of the Hongxi reign, Zhu Gaochi also passed away. This benevolent emperor reigned for less than a year, leaving before he could realize his ambition of recuperation and development. Crown Prince Zhu Zhanji succeeded to the throne, changing the era name to Xuande. Shen Du remained silent for a long time when he heard the news on his sickbed. He remembered Zhu Di patting him on the shoulder in the Fengtian Hall and saying, "Watch over this land for me," and he remembered Zhu Gaochi summoning him to the Eastern Palace when he was the Crown Prince to inquire about the details of the resettlement of the refugees in Jiangxi. Now Zhu Di was gone, and Zhu Gaochi was gone too. The old brothers who fought side by side with him on the battlefield of the Jingnan Rebellion were becoming fewer and fewer. Zhu Neng died on his way back from Jiaozhi, Tan Yuan died in Jiahe, and Huo Zhen had also passed away a few years ago. His son, Batu, inherited the title of Commander of the Left Guard of Duoyan and continued to guard the grasslands. He also thought of Qingshan—Qingshan had never been employed by the new dynasty over the years and had been teaching in Jinan as a commoner. He had also passed away a couple of years ago.

How much longer could he hold on? He didn't know. But he knew he still had some things left to do.

In the autumn of the first year of the Xuande reign, Shen Du's health improved slightly. Despite Zhao Laoliu's objections, he insisted on going out. Starting from the western neighborhoods of Beijing, he visited the families of the fallen soldiers of the Jingnan Campaign, house by house. Liu Shitou's mother, over eighty years old and hard of hearing, recognized Shen Du's footsteps—the same footsteps that came every autumn. She took Shen Du's hand, treating him like her own son, murmuring, "Shitou, you're back." Shen Du knelt before her, bowing his head to let her touch his face, without correcting her. Zhao Laoliu squatted outside the door, a pipe in his mouth, unlit, his eyes reddening.

He took out all the salary and rewards he had accumulated over the years and delivered them to each family on the list of fallen soldiers, one by one. Not in the name of the imperial court, but in his own name. After delivering to each family, he took out the well-worn list and circled the corresponding name. Once all the circles were drawn, he had Zhao Laoliu keep the list and hand it over to the Ministry of War's Department of Military Affairs. "This is the list of soldiers who died in the Jingnan Campaign. Every battle, every city, every fallen soldier's name and their garrison are listed here. From now on, annual pensions will be issued according to this list; do not omit anyone."

This list was later engraved on a stone tablet and erected in the main hall of the Jingnan Martyrs' Shrine outside Deshengmen.

In the winter of the second year of the Xuande reign, Shen Du's health had deteriorated significantly. He was emaciated, his face almost devoid of flesh, with only his high cheekbones protruding. Yet, his eyes still shone brightly, just as they had when Su Wanqing first saw him on the Jinan city wall. He leaned against the couch, an unfinished map spread before him—a complete map of the Ming Dynasty's territory that he had begun drawing in the twenty-second year of the Yongle reign, stretching from Liaodong to the Western Regions, from Jiaozhi to the Mongolian steppes, depicting every road he had traveled and every mountain and pass he had surveyed throughout his life. His brushstrokes were still as meticulous and precise as in his youth, but by the time he reached the last corner, his hand trembled so much that he could barely hold the brush. He put down the brush, leaned against the pillow to catch his breath, and smiled at Su Wanqing, who sat beside him on the couch. Su Wanqing took his hand, without speaking. Her hair was mostly white, and her eyes were lined with wrinkles; she sat there quietly, like a lamp.

Zhao Laoliu stood outside the door, holding Shen Du's prescription and an empty medicine jar. He still insisted on going to the Imperial Pharmacy every day to get the medicine according to the prescription. This old craftsman, who was also the head of the Construction Department, would stand at the pharmacy door for half an hour each time, personally checking every single ingredient. When he brought the medicine in, the steam blurred his face. He placed the medicine bowl by the couch, then went out, squatted down in the courtyard, put his pipe in his mouth, lit it, and then extinguished it.

That night, Shen Du summoned Zhao Laoliu, Gu Zhang, and Su Wanqing to his bedside. His voice was soft, pausing after each sentence, but every word was enunciated clearly. He said to Zhao Laoliu, "Laoliu, you've followed me for decades. From the Baigou River onward, you've always been at the forefront of every battle. Blowing up city gates, splitting deer antlers, pushing battering rams—you saved half the brothers' lives. Beijing is repaired, and the walls of the northern frontier are repaired too. It's time for you to enjoy your retirement." Zhao Laoliu knelt before the bed, tears streaming down his face, sobbing uncontrollably. He said to Gu Zhang, "Take good care of the surveyors from the Ministry of War. Maps are for fighting, not for hanging on the wall for decoration. You chose these young men; you're responsible for training them." Gu Zhang knelt on one knee, his old injury on his left arm making his posture slightly unsteady, but his back remained ramrod straight: "Understood, subordinate."

Finally, he looked at Su Wanqing. She sat on the edge of the bed, her eyes red but she didn't let the tears fall. Shen Du looked at her for a while, then slowly said, "From Jinan to Beijing, from the northern frontier to Jiangxi, you've followed me your whole life. Land reclamation, water conservancy, resettlement—these tasks were harder than fighting, but you never complained of being tired. From now on, you can't follow me everywhere anymore." He took a cloth bag from beside his pillow and handed it to her. Inside were all his savings and a military land reclamation and water conservancy strategy that he hadn't yet submitted. Su Wanqing took it with both hands, finally unable to hold back her tears, which fell onto the knot of the cloth bag, leaving a dark, damp stain.

In the second year of the Xuande reign, Shen Du passed away peacefully in his sleep. When he left, it was snowing heavily outside the window. One by one, the lights of thousands of homes in Beijing went out in the snowy night, leaving only the eternal lamp on the Deshengmen gate tower still burning in the wind and snow, illuminating the blue bricks on the city wall and the stone tablet inscribed with names in the main hall of the Jingnan Martyrs' Shrine below the gate tower.

In accordance with his last wishes, Shen Du was buried at the foot of the Great Wall outside Juyong Pass, facing north, alongside ordinary soldiers who died on the frontier. The inscription on his tombstone was written by himself before his death: "Tomb of Li Jingzhong, former Commander-in-Chief of the Ming Dynasty's Left Guard. A centurion of the Yanshan Left Guard's Pocheng Camp, he participated in the Jingnan Campaign, fighting in battles at Baigou River, Dezhou, Jinan, Dongchang, Jiahe, Gaocheng, Qimeishan, Lingbi, Yangzhou, and Nanjing. During the Yongle reign, he surveyed the vast frontier, repaired cities and dikes, and pacified displaced people. He died in the winter of the second year of the Xuande reign."

Zhao Laoliu built a small wooden hut next to his grave. He moved his bedding from Beijing to Juyongguan, and every morning he would get up to sweep away the fallen leaves and snow in front of the grave, then sit on the stone in front of the grave, smoke a pipe, and talk to himself while gazing at the northern mountains. He would say, "Master Li, the map you drew is still hanging in the Ministry of War. That kid Gu Zhang has led a surveying team to the Western Regions again. All the apprentices you taught have made something of themselves." A few years later, Zhao Laoliu also passed away. Gu Zhang buried him a dozen steps away from Shen Du's grave, just as he had said before his death—"After I'm gone, I'll be closer to Master Li, so we can take care of each other."

After Shen Du's death, Su Wanqing continued to serve in the Ministry of Revenue for many years, overseeing agricultural and water conservancy projects in Shaanxi, Huguang, and other regions, completing all the strategies Shen Du had left behind but hadn't had time to submit. After retiring, she moved to the foot of the mountain near Juyong Pass, where she lived by the Great Wall and the surrounding green hills. Before her death, she left a will donating all her agricultural and water conservancy notes from those years to the Imperial Academy. The inscription on her tombstone is only a single line: "Su Wanqing, Assistant Minister of the Ministry of Revenue, devoted her life to agricultural and water conservancy. An old friend of Li Jingzhong during the Jingnan Rebellion."

In the tenth year of the Xuande reign, Emperor Zhu Zhanji of the Ming Dynasty stood in the Fengtian Hall, before him lay the unfinished map of the Ming Dynasty's territory, left behind by Shen Du. From Liaodong to the Western Regions, from Jiaozhi to the Mongolian steppe, every city, every river, and every pass was clearly marked. In the lower right corner was a line of small characters—Shen Du's handwriting, neat and powerful, exactly the same as when he wrote his military pledges at the Baojiaying training ground in his youth. "Your subject, Li Jingzhong, presents this map to Your Majesty. The vast land is not on city walls, but in the hearts of the people."

Zhu Zhanji remained silent for a long time. He picked up his pen and wrote four characters in the upper right corner of the map: "May the mountains and rivers be forever secure."