No matter how unpleasant the quarrel had been, since they had invited people ashore, the night banquet still had to be held.

Han Qian and his father also stayed overnight at the residence, only making excuses the next day about the long journey ahead to their new posts and how they couldn’t delay too long. After the noon meal, they bid farewell and departed.

Han Daoming and Han Daochang, their intentions unfathomable, insisted on seeing Han Daoxun and his son off to the Water Camp Dock to watch them set sail.

Riding out of the Prefectural Governor’s office, Han Qian reined his horse to a stop on the street. Acting as if there were pebbles in his boot bothering his foot, he leaned against a corner wall, removed his boot, shook it a few times with the opening facing down, then put the boot back on and remounted his horse.

Once they boarded the ship and several sailors had raised the somewhat tattered mat sails, Han Daoxun finally saw Han Qian pull a wax pill from his bosom. Breaking it open revealed a strip of paper hidden inside. Only then did he understand why Han Qian had dismounted in the street after leaving his eldest uncle’s residence—someone had hidden this wax pill in advance at that corner wall, marking the spot for Han Qian to retrieve it.

“When did you arrange people in Chizhou?” Han Daoxun asked.

“When the Secretariat-Chancellery stamped the Ministry of Personnel’s memorial, I had Guo Nu’er, Lin Zongjing, and other retainer children go ahead westward to scout the local customs and conditions. I also hoped they might hear some interesting news to help pass our time,” Han Qian said. “I figured Uncle wouldn’t let us pass through so easily, so I specifically had them keep a closer watch on Chizhou to see who would be coming and going these past few days!”

“Is there anything unusual in Chizhou?” Han Daoxun asked curiously.

The *Commentaries on Employing Spies* was co-authored by Han Daoxun and Han Qian, so he knew Han Qian’s principle of employing spies was to alternate between overt and covert lines. Currently, their ship traveling the river had a very clear target—this was the overt line. Zhao Wuji, Guo Nu’er, and others leading the Left Bureau scouts who had departed ahead formed the covert line.

The covert line lurking in the shadows needed patience to endure loneliness. Unless they obtained critical information, they shouldn’t proactively contact them.

“Just because Uncle and Second Uncle can only think of using such clumsy methods to try to drive a wedge between us and the Third Prince doesn’t mean there isn’t someone ruthless and merciless in Uncle’s household,” Han Qian said with a contemptuous smile. “Does Father have any interest in knowing who secretly contacted Zhao Mingting’s men last night?”

“Ah…” Han Daoxun didn’t ask what exactly the Left Bureau scouts who had infiltrated ahead had discovered last night. Looking up, he saw his eldest and second brothers already turning back to the city surrounded by crowds on the river embankment. He merely sighed lightly without saying anything.

Even the elite scouts and secret agents under the Bureau of Military Affairs’ Department of Operations wouldn’t be very numerous, let alone the Secret Bureau’s Left Bureau that Han Qian had only been responsible for establishing for less than a month.

Even deploying every available hand to the maximum, Han Qian had only forty or fifty men.

After leaving Jinling, with high skies and deep mountains, distant ridges and dense forests, both sides’ limited personnel lurked in the shadows. Finding traces of the other was extremely difficult. They couldn’t even confirm whether Zhao Mingting’s side had actually sent people with intent to harm them.

Whether it was Han Duan or Han Jun who couldn’t resist Han Qian’s provocation last night and left the city to contact Zhao Mingting’s men, neither was what Han Daoxun wanted to see. But this also proved that Zhao Mingting had indeed sent people to harm them.

The Chizhou city river segment had constructed embankments. Beyond that, the river water had flooded, submerging the shallow shoals and sandbars on both sides. The ship hugged the southern bank as it sailed west.

At this moment the wind direction changed, with strong winds blowing in from the southwest. Old boatman Ji Fu skillfully directed the sailors to adjust the ship’s position and the angle of the mat sails, making the ship veer southwest so the mat sails formed an acute angle with the wind direction.

This was the so-called “catching wind from eight directions, sailing against the wind.” Zhao Ting’er, Qing Yun, and the other girls watched in amazement, never imagining a ship could sail against the wind.

Ji Fu’s son Ji Xiyao said proudly with a laugh, “This is just sailing against an oblique headwind. When facing a direct headwind, my father can still make the ship move forward.”

Han Qian sat on the deck, barefoot, lightly tapping the gunwale. He didn’t dwell on Han Jun’s late-night meeting with Zhao Mingting’s squad leader Ji Kun.

Ji Kun was very alert. After Guo Nu’er saw him meet with Han Jun, he quickly lost track of him again. But this confirmed that the Palace of Tranquility didn’t want his father to smoothly take up his post in Xuzhou.

What Guo Nu’er and the others could currently confirm was that within Chizhou city, there weren’t many men deployed by Zhao Mingting. And heading east from Chizhou, the Yangtze was relatively straight, with no suspicious vessels observed lingering on the river surface. Zhao Mingting’s side apparently understood that no matter how much Han Daoming disapproved of them, he wouldn’t permit them to make their move within Chizhou’s borders.

Before Guo Nu’er and the others could further ascertain Ji Kun and the others’ whereabouts, Han Qian could only observe and wait. At the moment, his attention was captured by other matters.

The principle of sailing against the wind seemed incomprehensible, though Han Qian knew that current-age people had mastered the technique of sailing against the wind quite early.

He noticed that when sailing against an oblique headwind, even after adjusting the ship’s angle, the wind still poured in from their diagonal front, and the ship’s body experienced obvious lateral drift.

This was clearly because the ship’s bottom was flat and couldn’t cancel out most of the lateral forces.

Also, due to the ship’s constant drifting, Ji Fu needed to direct the sailors to continuously adjust the sails and stern rudder to correct the ship’s course. This naturally wasted some time, but actually Han Qian discovered that the speed of sailing against a lateral headwind wasn’t at all slower.

Didn’t this mean that if they could eliminate some of the time spent on lateral drift correction, the actual speed of sailing against a lateral headwind would be much faster than sailing with a favorable wind?

This point puzzled Han Qian, as it clearly conflicted with part of the dream memories he had merged with.

How could sailing with a lateral wind possibly be so much faster than sailing with a favorable wind?

Could it be that a sailboat’s forward movement wasn’t entirely due to wind force pushing the sails and carrying the ship forward?

Was the dream knowledge incorrect, or was his integration of the dream knowledge not deep enough?

This wasn’t strange.

The person in the dreams, Zhai Xinping, excelled in finance and humanities, but his foundation in science and engineering was somewhat weak.

The sailboats built a thousand years hence could reach speeds of a thousand li per day using wind power, whereas their current voyage on the open river surface averaged only about two hundred li per day even traveling day and night—a difference of four or five times. Han Qian knew this obviously couldn’t be fully explained with simple mechanical knowledge.

Of course, even if Han Qian didn’t understand why, knowing that it was so, he could still think of ways to greatly improve new-style sailboats’ speed.

He couldn’t help thinking: never mind hoping for a thousand li per day—if his father in Xuzhou could truly build fast sailboats capable of five or six hundred li per day, the journey from Xuzhou ships to Jinling could be reduced from over a month to around ten days.

If after understanding the water conditions they traveled day and night, the journey time would be further greatly reduced. This efficiency would improve by four or five times at once. From a commercial transport perspective, the advantages here would far exceed everyone’s imagination.

Though building new fast ships would require an extremely long time, Han Qian thought carefully—traditional sailboats weren’t beyond modification.

“Are you thinking about the secret agents dispatched by the Palace of Tranquility?” Han Daoxun walked through the cabin and sat down, asking, “Are you planning to go ashore yourself?”

If Guo Nu’er and the others tracked down the whereabouts of the men Zhao Mingting had dispatched, Han Qian would naturally go ashore himself to break the situation. But there was no rush at the moment—he would wait for Guo Nu’er and the others to give a further signal.

Han Qian shook his head and said, “I’m thinking that even without building new ships, the ship beneath our feet can be modified. Father, have you noticed that when sailing against an oblique headwind, the actual speed increases tremendously? It’s only because the ship’s hull is constantly pushed sideways by the lateral wind, requiring constant adjustment of the ship’s direction, wasting considerable time, that it doesn’t appear fast?”

“Mm!” Han Daoxun had been led by Han Qian these past days to think much about the vessel they rode. He nodded to indicate he’d noticed this too, saying, “I’m also quite puzzled about this—why does lateral wind increase ship speed so much? I just went to the stern to ask Ji Fu about this, but he doesn’t understand why either.”

Han Qian couldn’t figure out the principle of lateral wind acceleration either. This obviously wasn’t something people of this era could understand. Setting that aside, he said, “Never mind the matter of lateral wind acceleration. What I’m thinking is, if we nail thick water-blocking boards to the ship’s bottom, when wind force pushes the ship sideways, the thick boards could resist it with the force of water flow, making the ship’s hull more stable. Reducing the time spent adjusting the ship’s position, wouldn’t the actual sailing speed become much faster?”

Han Daoxun pondered for a moment and also felt Han Qian’s words made considerable sense. He laughed, “This point can be immediately modified and verified after we reach Xuzhou.”

“Perhaps we don’t need to wait until Xuzhou to verify it,” Han Qian said with a smile.

“How to verify it?” Though Han Daoxun’s mind was also quick, just as he asked, he realized there was a method to verify whether what Han Qian said was feasible. “The fundamental point of your idea is to block water flow from the side to stabilize the hull. We currently have no way to flip the ship over to install water-blocking boards on the bottom, but we can add boards on the ship’s sides to insert into the water?”

“That’s exactly what I’m thinking. Let me call over the Ji father and son to see if we can work out a method to implement this immediately.” Han Qian had long since become action-oriented. Standing up, he called across the low cabin that reached neck-height to Ji Fu and Ji Xiyao at the stern.

After Ji Fu heard Han Qian explain the principle, he pondered for a long while. It was only when his son Ji Xiyao secretly tugged his sleeve that he reluctantly said, “…This seems worth trying.”

Of course, Ji Fu inwardly felt Han Qian was purely causing trouble. This craft had been passed down through generations—if it could be improved, among the boat-building masters of previous generations there was no lack of brilliant geniuses. Wouldn’t they have changed it long ago?

However, Ji Fu knew his son’s secret sleeve-tugging was reminding him that this young master before him truly wasn’t to be trifled with. Thinking again that letting him mess around like this wouldn’t cause major problems, he reluctantly agreed to try.

The lower hold contained abundant materials for repairing sailboats to guard against damage during the voyage.

Clearing space at the bow, Han Qian directed people to join and widen thick boards using two old rudders, inserting and securing them into the water from both sides of the gunwale. They worked until the slanting sun spread across the river before completing the work. But when they continued sailing against the oblique headwind, the ship’s hull was indeed much more stable.

And eliminating the time spent correcting lateral drift, Ji Fu, as an experienced sailor and master craftsman, could accurately estimate that ship speed had increased by at least forty percent.

“Young Master’s idea is truly wonderful! Old Ji never imagined this method would actually work so well,” Ji Fu praised repeatedly. He hadn’t expected that simply joining thick boards from two old rudders and inserting them into the water would have such an obvious effect. Not only did speed increase, but with the hull no longer swaying, those aboard were much more comfortable. The sailors no longer needed to frequently adjust the ship’s position, saving tremendous effort.

“Besides killing people, my mind doesn’t seem stupid either,” Han Qian said with a slight smile.

Ji Fu and his son Ji Xiyao dared not respond in their alarm.

Han Qian looked up at the sky. With not a cloud for ten thousand li, a pale crescent moon had already appeared in the eastern sky—tonight was destined for a sky full of stars and moon. He said to Ji Fu, “As much as possible, use the lateral wind to sail. We won’t rest tonight. See if we can enter Jiangzhou territory by noon tomorrow.”

Seeing Ji Fu look over seeking confirmation, Han Daoxun also nodded, telling Ji Fu to proceed. He understood Han Qian’s thinking.

All along their journey they hadn’t seen many suspicious figures watching from both riverbanks. This meant the men Zhao Mingting had dispatched weren’t particularly numerous—nor could they be particularly numerous—and they were also guarding against being spotted and ambushed again as enemy agents.

The men Zhao Mingting had dispatched very likely relied on their ship’s speed to roughly estimate when they would arrive at Jiangzhou, Ezhou, Yuezhou, and other places, then had people watching for them at fixed locations.

If they could greatly increase their sailing speed, they might be able to disrupt the deployment and rhythm of the men Zhao Mingting had sent, causing them to reveal more flaws for the Secret Bureau Left Bureau’s scouts and agents to capture, thereby seizing the initiative.