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

On the very night Dezhou was captured, Zhu Di spread out a complete map of Nanjing Yingtian Prefecture in the main hall of the government office. It wasn't the entire Shandong province, nor the Hebei plain, but the entire Jianghuai region extending to Jiangnan. The candlelight flickered in the draft, and he used his sword sheath to hold down the corner of the map, drawing lines with his finger from Dezhou southwards, past Jinan, past Xuzhou, past Huai'an, all the way to the Yangtze River.

"Your Highness." Zhu Neng stood before the desk, the bandage on his right arm soaked with blood again—his old wound had reopened during the street fighting in Dezhou when he led his cavalry to break through Sheng Yong's personal guard, and the army doctor hadn't had time to re-bandage it. He looked at the route drawn by the finger on the map, his Adam's apple bobbing. "Jinan hasn't been taken yet, and Tie Xuan is still here. If we bypass Jinan and head south directly, our retreat could be cut off by Tie Xuan at any moment."

"Tie Xuan has no more troops." Zhu Di didn't look up, his finger continuing south. "The grain reserves in Jinan can last for three months, but his mobile forces were wiped out by Sheng Yong at Jiahe and Gaocheng. He dares not leave the city. If we bypass Jinan, he can at most send a few small detachments to harass the supply lines, posing no threat."

He straightened up, his gaze shifting from the map to the generals in the tent. "Sheng Yong retreated to Jinan, Wu Jie retreated to Jining, and Ping An retreated to Xuzhou. Jianwen still has three important towns between the Yangtze and Huai Rivers: Huai'an, Yangzhou, and Luzhou. On the south bank of the Yangtze River, there are Sheng Yong's former troops and the Nanjing garrison. But these forces are scattered—Sheng Yong is in Jinan, Mei Yin is in Huai'an, and Xu Huizu is in Nanjing. The three forces are hundreds of miles apart, and none can save the others. Our army, riding the momentum of our great victory at Dezhou, will take advantage of the gap between Jinan and Xuzhou before they can converge, advance south, head straight for the Yangtze River, capture Yangzhou, take Zhenjiang, and besiege Nanjing. Once Nanjing is taken, this battle will be over."

A long silence fell over the tent. Zhu Neng remained silent, as did Chen Mao. Huo Zhen leaned against a pillar by the tent entrance, his dagger still embedded in his horse's bone, his eyes gleaming—"A direct assault on the capital"—these four words meant victory, pastures, and countless cattle and sheep to the cavalrymen of the grasslands. Shen Du stood half a step behind Zhu Neng, looking down at the map, his fingers tracing circles on the hilt of his sword. Zhu Di's strategy was correct. The Yan army had fought its way from Hebei to Shandong, each battle a hard-fought siege, city after city, suffering heavy casualties. If they continued to stalemate with Sheng Yong and Tie Xuan in Shandong, reinforcements from the south would eventually arrive from Jiangnan. But bypassing Jinan and striking directly at Jianghuai was like flipping the chessboard—the offensive and defensive positions shifted, completely disrupting Jianwen's leisurely troop deployment.

But this road was fraught with difficulty. The straight-line distance from Dezhou to the Yangtze River exceeded a thousand li (approximately 500 kilometers), requiring passage through the river network of northern Southern Zhili and crossing the Si River, Bian River, and Huai River. Along the way, two large armies led by Mei Yin and Xu Huizu were poised to intercept them at any moment. More importantly, the Yan army's supplies of provisions and gunpowder had reached their limit after their advance from Jiahe to Gaocheng and then to Dezhou. The grain reserves in Dezhou were enough to feed the entire army for twenty days. If they didn't reach the Yangtze River within those twenty days, starvation would cripple the Yan army without the Southern army even needing to lift a finger.

"Supplies," Shen Du spoke, his voice not loud, but everyone in the tent heard him. "The shortest route from Dezhou to the Yangtze River is through Yanzhou, Peixian, and Suzhou, crossing the Huai River at Xuyi, then through Tianchang and Liuhe, to Guazhou Ferry on the opposite bank of Yangzhou. The entire journey is about 1,100 li. Light cavalry can reach the destination in ten days by rapid march, but the main army's provisions and supplies cannot keep up. Along the way, we will pass through several cities controlled by the Southern Army—our army needs to collect boats and build pontoon bridges along the way, and we must not linger at any point for too long."

Zhu Di looked up at him, a slight twitch at the corner of his mouth. "You're right. So this time, we can't bring a large baggage train south. Each soldier should carry seven days' worth of dry rations, and all gunpowder and arrows should be loaded onto pack animals. We won't bring any heavy siege equipment like battering rams or siege ladders. The entire army will advance lightly, bypassing all the less important cities. Speed ​​is of the essence; take down those that block our way, and leave those that don't. The only place we need to forcefully attack is the ferry crossing on the north bank of the Yangtze River. Once we reach the Yangtze, the Yangzhou treasury will be our supply depot."

The Yan army completed its light reorganization at the gates of Dezhou. All heavy machinery was dismantled and left in Dezhou; the iron parts of the battering rams were melted down for craftsmen to forge weapons; gunpowder was repackaged into smaller bundles for easy carrying; and each soldier received seven days' worth of dry rations. Zhu Di brought only 60,000 elite troops—20,000 light cavalry, 30,000 infantry, and 10,000 mounted archers from the Doyan Three Guards. These 60,000 men were the last and most capable core of the Yan army.

Shen Du's centurion unit was incorporated into Zhu Neng's vanguard. Before setting off, he pulled Gu Zhang and Zhao Laoliu together and drew a southward route on the muddy ground with his dagger. His blade paused briefly east of Yanzhou. "Mei Yin has amassed a large force in Huai'an; he is Jianwen's main force in the last line of defense north of the Yangtze River. If we bypass Jinan, he will definitely move south to block us. Before crossing the Huai River, we cannot let him know that our ultimate goal is to cross the river, not Huai'an. Your Highness's intention is to have the Doyan Three Guards spread false information, saying that the Yan army's target is Huai'an, thus pinning Mei Yin to the spot."

At dawn the next day, the Yan army's light cavalry set off from Dezhou, heading south along the Grand Canal at such a speed that even the garrisons of the counties along the way couldn't react in time. After capturing Yanzhou in two days and one night, Zhu Di didn't stop and continued his southward advance. On the seventh day, the vanguard had reached Pei County, more than 700 li (approximately 350 kilometers) away from Dezhou where they had started. Zhu Di reined in his horse outside Pei County, glanced back at the dust raised by the marching column, muttered something under his breath, and then said to the messenger, "Go tell Li Jingzhong that his surveying and scouting team has pinpointed the route too accurately. I've ridden horses for half my life, and this is the first time I've covered 700 li without missing a single fork in the road."

South of Pei County, the terrain begins to soften. The permafrost and loess of Hebei are gradually being replaced by river networks and wetlands, and the air begins to smell of water. Shen Du stands on an abandoned ferry crossing outside the south gate of Pei County, facing the Bian River. The river is not wide, but the current is swift, and reeds grow on both banks, their surface shimmering with a grayish-white sheen under the moonlight. He probes the wooden planks of the ferry crossing with his scabbard—they are rotten.

"Zhao Laoliu, the pontoon bridge." Shen Du sheathed his knife. "Does the supply battalion have enough rope?"

"That's enough. Before leaving Dezhou, I brought all the hemp ropes from the supply camp—twelve ropes, each thirty feet long." Zhao Laoliu, with his pipe in his mouth, looked up at the reeds on the opposite bank. "The river isn't wide, but the current is swift. A pontoon bridge won't be stable with just ropes. We need to drive stakes into both banks." Shen Du ordered him to drive stakes into the river overnight. At the same time, he found three abandoned ferries from the supply camp, dismantled the planks, laid them on the ropes, and secured them to both ends with stakes. The pontoon bridge was completed before dawn. Although rudimentary, it allowed lightly armed infantry and cavalry to cross in batches.

Day 11. The Huai River came into view from Shendu. From a high slope north of Xuyi, the Huai River resembled a giant gray python lying on the plain, its width so great that the opposite bank was invisible—at least three hundred zhang (approximately 150 meters). The water shimmered with a leaden gray light under the midday sun, its waves small but its undercurrents turbulent. The ferry crossing was empty; the Southern Army had already gathered all the ferries along the riverbank to the south, leaving not even a single fishing boat behind.

Shen Du lowered his binoculars, his brow furrowing. "There are no boats. The river is three hundred zhang wide; a pontoon bridge can't be built—the ropes aren't long enough, the current is too swift, and the wooden stakes won't stand in the water." He drew a line on the ground with his sword, outlining the Huai River, and then marked the locations of several ferry crossings along the river. "Mei Yin is on the south bank, and Sheng Yong's remnants are also heading this way from Jinan. If we can't cross the river within three days, the Southern Army will be able to form a defensive line on the south bank of the Huai River—then the Yangtze River is out of the question, and the Huai River will be our final destination."

Zhu Di stood on the high slope, gazing at the Huai River in silence for a while. He didn't get angry, nor did he press for answers; he simply asked Shen Du, "All the ferry boats have been taken away. What can you do?"

Shen Du remained silent for a long time. Then he uttered a single word: "Boats." He turned and pointed northwards, towards a direction already obscured by dust and smoke. "Weishan Lake. There's the Nanyang Water Fortress on Weishan Lake, with nearly a hundred flat-bottomed cargo boats and small fishing boats used for transporting grain and fodder by local waterways. We're not burdened by siege equipment, and we won't carry any more grain—we'll send two thousand light cavalry, marching day and night to Weishan Lake, seize the boats, and then tow them south along the Si River to the north bank of the Huai River. Within three days, we can tow back enough boats to ferry the vanguard across in one go."

Zhu Neng was stunned. He had fought on land for half his life, and this was the first time he had ever heard of someone wanting to tow a boat from a lake two hundred miles away to cross the river.

Zhu Di did not hesitate and turned to look at Zhu Neng. "You will personally lead two thousand light cavalry to Weishan Lake. I want to see boats within three days."

Two thousand light cavalry set off from Xuyi, heading north along the Si River. Without rest, they reached Weishan Lake in a day and a night. The garrison at Nanyang Water Fortress numbered less than a thousand. Mei Yin had concentrated all his forces along the Huai and Yangtze Rivers, never expecting the Yan army to turn back and seize a water fortress on a lake. Zhu Neng captured the fortress in half an hour. Nearly a hundred flat-bottomed cargo boats and fishing boats were moored within the fortress. Though dilapidated, they could float, perfect for transporting troops. Standing on the fortress's pier, Zhu Neng looked at the lake's surface, dyed red by the setting sun, and at the countless broken boats, and couldn't help but curse, "This is the first time in my life I've seized boats—and it's just to row to the Huai River!" He strung the cargo boats together with hemp ropes into three rows, each towed south along the Si River by laborers and mules pulling ropes from the shore. The boats rattled and creaked in the shallow water, the current pushing against the direction of the towing, making the procession extremely slow. The cavalrymen also gave the extra warhorses to the laborers to harness. At dawn the next day, the three cargo boats ran aground at the confluence of the Si River and the Huai River. The fleet was towed until the evening of the third day, when they finally managed to drag the dilapidated fleet to the north bank of the Huai River.

The crossing began at dawn.

As Shen Du launched the first cargo boat, a thin mist rose over the Huai River, obscuring the movements of the Southern Army sentries on the opposite bank. Huo Zhen's mounted archers dismounted and boarded the boat, tying their horses to the stern and leading them across the water. Zhao Laoliu stuffed his pipe into his robes, grabbed a rope, and jumped onto the bow. Before the boat even reached the shore, the Southern Army sentries on the opposite bank finally spotted the boat on the river and frantically banged their gongs. Arrows rained down from the south bank, striking the cargo boat's planks with muffled thuds. Gu Zhang stood at the bow of the first cargo boat, holding his shield to block the arrows. His old wound on his left arm reopened with the exertion, blood trickling down his arm guard, but he gritted his teeth and remained silent. By the time the cargo boat reached the shore, his sword was already drawn, and he felled the first Southern Army infantryman who charged forward. As the infantrymen fell, spearmen rushed onto the beach behind them, their spear tips overturning the barricades that were trying to block the crossing. Zhu Di's cavalry then landed, and the 60,000-strong Yan army and the main force of the Southern army fought fiercely along the Huai River for a day and a night, finally breaking through the Huai River defense line hastily erected by Mei Yin.

In the midst of the rout, Mei Yin rallied his remaining troops and retreated towards Puzikou on the north bank of the Yangtze River. Behind him lay the last line of defense he had built for Jianwen—the Yangtze. The Yan army, stepping over the baggage and wrecked cargo ships left behind by the Southern army at the Huai River ferry crossing, continued their southward advance. When the vanguard intercepted the straggling Southern army rear guard near Tianchang, Shen Du glanced back at the route they had come from—the ropes of the pontoon bridge were still in place, the cargo ships were still stranded on the shallows, and countless hoofprints and footprints crisscrossed the muddy riverbank. From Dezhou to the Huai River, a distance of 1,100 li (approximately 650 kilometers), they had traveled for fourteen days. The Yangtze River lay ahead.