Isolated town in northern border region

The rubber plantations outside Yingzhou City gleamed with a dark green sheen in the afternoon sun.

Xiao Lie squatted beside a rubber tree, watching the craftsman use a specially made curved knife to cut a shallow slit in the bark.

The milky white liquid slowly seeped out from the cut, dripping down a shallow bamboo trough into the ceramic bowl below, thick and slow.

He reached out, dipped a little into his fingertip, and rubbed it. The adhesive was viscous and resilient, indicating it was high-quality natural rubber.

He stood up and spoke to the craftsmen beside him.

"Let's try harvesting for ten days first, and see how much sap we can get from each tree."

"Write down the process steps and compile a manual later."

The craftsmen agreed in unison.

Luo Daniu squatted down beside them, looking at the white liquid in the ceramic bowls, and reached out to poke it.

"Your Highness, can this thing really make that... sulfur... thing you mentioned?"

Xiao Lie slapped his hand away.

"It's sulfidation!"

"Don't touch it, the raw rubber is too sticky, it won't wash off."

Luo Daniu withdrew his hand.

When the first batch of raw rubber was transported back to the State of Chu, Qian Wanli had already set up a temporary workshop in the palace.

In front of him were several pale yellow blocks of raw rubber, next to sulfur powder and several earthenware jars.

Zhou Xun came to check once, but he was choked by the smoke before he could even stand there for the time it takes for an incense stick to burn. After that, he only asked someone to send charcoal every other day and never inquired about it again.

Every time Qian Wanli failed an experiment, he would make a note on a piece of paper and draw a horizontal line with a charcoal pencil. He would draw more and more horizontal lines.

The first five trials all failed.

The first time the glue block was heated, it melted directly into a puddle of sticky liquid, and after cooling, it became even stickier than before.

The second time, too much sulfur was added, and the rubber block became so hard that it felt like a stone when tapped, with no elasticity.

The third time, the heat wasn't controlled properly, and the surface of the rubber block became charred and brittle, breaking easily when broken.

Qian Wanli squatted in front of the stove, examining the charred plastic block in his palm, turning it over and over. After a while, he threw it into the waste bin in the corner.

He squatted next to the waste bin for a while, then stood up and opened the window to let the pungent sulfur smell out.

The sixth experiment took place on a sweltering afternoon.

Qian Wanli adjusted the sulfur ratio, adding only a small amount, then put the mixed adhesive into a ceramic jar, covered it, and heated it with charcoal.

He watched the fire from the side, and only when grayish-white smoke came out from the gap in the lid did he lift the lid, use tongs to take out the piece of plastic that had turned dark brown, and put it in water to cool.

The cooled rubber block has a smooth surface, is not sticky, and has a noticeable rebound when pressed.

Qian Wanli took it in his hand, squeezed it, and then pulled it. The sensation on his thumb pad was quite peculiar.

He took a deep breath, placed the block of tape on the table, cut off a small strip with a knife, held one end in each hand, and pulled hard. The dark brown tape was stretched to more than twice its original length, but it still did not break.

"It's done!"

His voice was low, as if he was afraid of startling something.

"This thing...it's done!"

He squatted in front of the table and pulled it repeatedly seven or eight times, but each time it bounced back to its original shape without any change.

He suddenly burst into laughter, laughing like a child who had just stolen candy, then turned and rushed to the door, shouting outside.

"Someone! Go tell the Prince! The rubber... is done!"

When the news reached Yingzhou, Xiao Lie was reviewing Chen Guo's old files. He was overjoyed after reading the letter and immediately picked up paper and pen to start planning how to use the rubber.

"Brain! Think!"

"Besides sealing steam engines, what else can rubber be used for?"

"Drive belt, shock absorber, tires, waterproof mat..."

When the first batch of vulcanized rubber sealing rings was delivered to Youzhou Steel Plant, Li Dachui had just come from the furnace, his face still covered in coal dust.

He was Old Zhou's apprentice and a veteran of the Youzhou factory.

He weighed the dark brown rubber ring in his hand, then brought it closer to his eyes to examine it carefully, and scratched it with his fingernail.

"This thing... it's all soft and flimsy, what can it even do?"

"A young craftsman nearby said."

"Manager Qian said this is used to seal the steam engine."

Old Zhou glared at him.

"Sealing a steam engine? Those things get incredibly hot inside, can this soft thing withstand that?"

Muttering to himself, he took the sealing ring and walked to a steam engine that was still in trial operation. He squatted down and replaced the old seal on the piston, which was made of hemp rope and oilcloth.

He could feel the elasticity of the rubber pressing against the screw surface as he tightened the bolts.

The moment the steam engine started, the piston began to reciprocate, but white steam did not emerge from the joint between the cylinder and the piston as usual.

Old Zhou squatted to the side and stared for the time it takes for an incense stick to burn before standing up straight.

"It's not leaking air anymore?!"

"It's really sealed off!"

He touched the rubber seal, his fingertips lingering on the smooth surface for a moment, then turned and walked out of the factory.

"Tell the prince, our steam engine in the northern frontier is finally a success!"

When the news reached Yingzhou, Xiao Lie was marking the new railway planning line on the map.

He didn't look up.

"Mark the sulfur-producing areas on the transportation map and classify them as secondary materials."

Chen Hu accepted the order and left.

Xiao Lie put down his pen, walked to the window, and looked north.

The month that rubber seals were rolled out to factories across the country, the first batch of new bearing gaskets appeared on railway lines, water pumps in mines ran continuously for seven days without leaking for the first time, and steam looms in textile factories began to operate at full capacity.

Raw rubber was transported from Chen Guo to northern Xinjiang, where it was processed into sealing rings in workshops and then sent back to factories in various prefectures, spreading out along the railway lines to the south and north.

Qian Wanli wrote a sentence in a letter to Zhou Xun.

"This year's autumn taxes in northern Xinjiang have doubled."

After reading the letter, Zhou Xun folded it neatly and put it in the drawer, saying only one sentence to the messenger.

"Reply to him that doubling isn't enough; it needs to double again next year!"

The entire Chu Kingdom was immersed in the joy of its rapid industrial progress, and Xiao Lie's plan moved forward steadily like a clock that had been recalibrated.

But the atmosphere at the Yan-Shu camp in Xuzhou was quietly turning cold.

Jiang Min realized this on the twenty-second day after moving into the camp.

That morning, as usual, she went for a walk outside the tent and found that the guards at the camp gate had been replaced by a different group of people, whose faces were even more unfamiliar than before.

She paused for a moment, then turned and went back to her tent without asking any further questions.

That afternoon, Yan Ji and Yang Wei visited together, and sat at the table in silence for a long time before speaking.

Yanji laid his fingers flat on his knees and then clenched them again, repeating this several times.

"Your Highness, His Majesty has sent someone to deliver a message, saying..."

Yang Wei took over the conversation.

Emperor Jing wanted to invite the Princess Consort back to her parents' home.

Jiang Min held the teacup, the warmth of her fingertips slowly seeping up through the cup.

"What do the other two think?"

Yan Ji did not answer immediately.

Yang Wei looked down at his hands resting on his knees.

"Your Majesty is still considering it."

Jiang Min put down her teacup and paused between the two men.

"Going back to my parents' home..."

"snort!"

"If I leave the camp, I will likely be assassinated."

She paused for a moment.

"He fears the infamy of killing his sister. If I die in the Yan-Shu camp, my husband will slaughter you all."

"By then, do you think Jingguo will send troops to rescue you?"

Yan Ji and Yang Wei exchanged a glance, their eyes filled with bitterness.

A weak nation faces a dilemma: to advance or retreat.

That night, Jiang Min sat alone under the lamp for a long time, the wind outside the tent carrying the sound of the sentry's footsteps and the crackling of the campfire in the distance.

She spread out a piece of paper, wrote a secret letter, folded it, and handed it to the maid beside her.

"The message was delivered by carrier pigeon to Yingzhou."

The letter contained only four words.

"I am in danger."

The maidservant left the camp under cover of night and disappeared at the end of the official road.

In Yingzhou City, Xiao Lie was reading the trial report of the first batch of vulcanized rubber sealing rings sent by Qian Wanli when he received Jiang Min's secret letter.

After he finished reading those four words, his eyes turned cold.

Luo Daniu stood at the door waiting for him to speak.

"Order the entire army to rest and reorganize, and then immediately head north."

"Chen Hu stayed behind to oversee the rubber plantation and stabilize the livelihoods of the people."

Luo Daniu cupped his hands in greeting.

"This subordinate will take care of it immediately."

Xiao Lie stood motionless by the window, while the northern horizon in the distance darkened.

The next day, the elite troops of the northern frontier broke camp and headed north, marching swiftly and advancing like the wind.