Goryeo's Great Wall
Even now, Goryeo had made tremendous progress. The repeating crossbow workshops, the cement made from lime, the Yodong Ironworks with its coke-fueled steel mills, the threshers—these alone represented a giant leap forward.
If they could add spinning machines and looms, textiles would be no problem. The catch was that they needed to be near rivers, so they'd concentrate around the Taejah River area, though they'd gradually expand to the peninsula as well. To avoid losing land, they'd need to build cranes too.
Hold on. Wait a minute. This could get problematic.
The Taejah River was close to the Yodong border. If the Mongols raided them, it would be disastrous. If the Mongols sought revenge... ugh, unthinkable. Before they came, they needed backup facilities on the peninsula and walls along the Yodong border. To make the defensive line solid, there was no choice.
"I've gotta change plans a bit."
Gaegyeong's new city needed work too. First, finish Yoyang, then the Yodong border walls. Gaegyeong could come after Seogyeong, pushed back a little further. Even she couldn't handle building Yodong walls and Gaegyeong at the same time.
"Change plans?"
"We've got a lot more to protect now. Once Yoyang's sewer system is done, we'll put Gaegyeong on hold for a bit."
She answered Kim Jun's question with a suitably dazed look. They needed cranes and walls. Roughly five hundred of them, used to stack as much stone as possible. Cover every likely Mongol approach with the barbed wire they'd make here. It all had to be finished by the end of the western expedition.
"Suddenly?"
Yi Jang-yong was shocked, but there was no helping it. Look at that—the countless waterwheels and repeating crossbow workshops clustered along the Taejah. The coke ironworks, and soon spinning and weaving machines everywhere. They'd expand to the mainland too, but right now, everything was focused there. They had to lay the groundwork to defend it all.
"With all the resources in Yodong, facilities are starting to cluster there. What happens if the Mongol army invades? Everything gets smashed to bits."
Even assuming the Mongols just looted and left, it was risky. If they burned it all, the towers they'd so carefully built would crumble. Honestly, even now, if the Mongols took offense and wrecked the Taejah ironworks and workshops, what then? That meant walls first. Once built, defense wouldn't be hard. If the steppe routes were cut, they could just use sea paths. No one knew how long the western expedition would last anyway. Finish before then. They had to develop toward the sea regardless—America demanded it. Abandon the shipbuilding cheat map? Unthinkable. Better the sea than punching through Mongols, and ships needed development anyway.
"That's true, but..."
"We have too much to protect now. All those waterwheels, repeating crossbow workshops, ironworks—they could all go up in smoke, the future of Goryeo with them."
History was full of advanced civilizations collapsing overnight due to war.
"When will Yoyang be finished?"
"Sewer facilities in about a month."
One month. Fine. Finish Yoyang. But right after, straight to wall construction.
"Building walls takes massive manpower. You know that, right?"
"Yes. I know. But we have to do it."
The laborers from Yoyang could shift to walls. They had to. Can't just order it for free, though. Goryeo already circulated currency. Pay wages, and they'd work. Immigrants were still pouring in. Recently, thousands of Han Chinese fleeing Song plunder had crossed to Yodong and the mainland. Use them. Public sentiment was an issue, but package them as Goryeo folk or highlight their Goguryeo or Balhae ancestry for mainland treatment. In exchange, make them learn Goryeo speech, like the Jurchens learning for Abka-i Hehe. That's why cranes were key.
She showed Yi Jang-yong the crane blueprints she'd prepared long ago, explaining the plan.
"After this, mass-produce five hundred cranes and deploy them. Keep the cement kilns running nonstop, day and night."
Fill the walls with cement. Make it so grand that when Mongols saw it, they'd think, 'That day, the Mongol army remembered.' Not like China's Great Wall, breached repeatedly by foreigners. A perfect one, clearly marking Goryeo's world under Heaven.
"Is that necessary?"
"Those Taejah facilities will shape Goryeo's future."
More precisely, they'd spark an Industrial Revolution like Europe's. To make it happen, protect them. Song's failed because of various reasons, but Mongol destruction was key. In eight months, prioritize walls along plains and rivers good for cavalry.
"I get that, but after the Commandant killed seventy thousand of them, you think they'll come again?"
True. From the Mongol perspective, it was the worst defeat. If they really wanted Goryeo, they'd have hit after Jin or brought massive supplies before. But who knew? Complacency could doom them.
"You never know with people. Look at Sui—they ignored rebellions at home, uprooted the nation's core just to crush Goguryeo."
Sui lost local control beautifully. Not solely Goguryeo's fault, but it primed rebellions. Point was, madmen existed. After finishing the west and expanding, who knew what Mongols would do? Make it certain. Victories like Subutai's wouldn't repeat—miracles, and they'd lost thousands, including Jurchens. Secured Yodong, but still risky.
A month passed, and Yoyang's new city was finally complete. Cement roads weren't fully laid yet, but sewers were done. Goryeo's abundant lime had saved them. Not modern mass-production, but enough for one city. Pipes could corrode if poorly made—some future reader might nitpick. So she mixed rebar and cement with centrifugal force for dense pipes.
Waterwheels turned the Taejah's flow. Massive wheels spun slowly but powerfully. 2-meter wooden wheels linked to 20cm iron ones by oxhide belts. Vibration was tricky, but who was she? Counterweights stabilized it. Teach Song and Jin artisans, and their Goryeo apprentices. Install the speed-up gear. High-speed spin: mount four iron wheels on the floor, top with cylindrical molds. Furious rotation presses wire and cement densely by centrifugal force. Corrosion-proof pipes lasting a century. All thanks to hundreds of waterwheels and proper wire production—even from Chungju, hauled up.
Wire frames with cement pipes laid sewers complete—no major issues.
"Heard you've been busy with this and that lately—this it?"
"Some hygiene setup?"
"Before the capital Gaegyeong, even!"
"Lady Yeon really thinks of us Jurchens. True Great Jin Emperor!"
"Abka-i Hehe is truly magnificent."
Jurchen reactions were glowing. Future martial overlords developing Yoyang before Gaegyeong? Obvious implications. They favored technicians and artisans, with state support for training in various fields. Current numbers had limits—increase them. Industrial Revolution was inevitable. With immortality, failing would be pathetic. Within centuries, unrivaled in East Asia.
Even Jusuk came from Gaegyeong as overseer.
"Ho, impressive. Byeokrando livens Gaegyeong, but Yoyang looks more advanced."
It did. Jusuk seemed hooked, tapping the cement road with his foot.
"Gaegyeong starts in two years. Terrain makes it slower than Yoyang, so this first."
Gaegyeong's location sucked.
"Two years from now? Why not start now?"
Because walls first.
"You know too, General Jusuk—Goryeo has much to protect now, and Mongols have held back. Preparing for the worst."
More to guard meant more preparation. Original history's Goryeo fought desperately amid ruins, but now Hwangnyongsa stood, and Taejah hosted this era's factories.
"Mongols starting war again? They don't have endless Han hordes like China."
But auxiliary troops changed that.
"Probably not. But caution hurts nothing. Mongols mainly absorb conquered armies as auxiliaries. Tens of thousands of Han troops, and it's Goguryeo wars reborn. So prepare. Goryeo full of loot? Wide borders? Tempting. But walls change it."
'A' and 'eo' made all the difference. Wide open borders vs. vast walls blocking routes—which broke war spirit more? The latter. Mongols might think, 'Fuck, too costly,' and back off.
"Fair point."
As a top general, Jusuk got it. Records questioned his prowess, but he thought ahead.
"Old Goguryeo built the Thousand-li Wall. No reason we can't."
Border was too vast. Yeonun 16 Prefectures blocked central powers well, but Mongols behind. Yodong was key. Best: destroy Mongols. Subutai dead, but empire wouldn't collapse instantly. Their combat power mattered. Subutai one-trick? History split post-death. Yelu Choeje was reforming now—not crumbling easily. When to topple Jin's dying empire?
"Still, where to get manpower for walls? Short timeline needs lots."
True. Massive walls to block Mongols in Yodong.