Making Gunpowder in Goryeo
A niter bed takes at least a year to set up, but in the long run, the potential is more than strong enough. Whether in the outskirts of Gaegyeong, near the military camps, or down south anywhere, as long as we establish niter beds, we can produce massive quantities of gunpowder without importing soda ash.
If we can just manufacture cannons and iron cannons. We could hold out against the Mongols in war.
How could Goryeo—with less than half the population of the Liao—how could Goryeo, a mere fraction compared to the Song's numbers—maintain balance between the Liao and Song, even bullying the Song? Sure, calling Goryeo straight-up thugs against the Song is exaggeration and nationalistic hype. But the very fact that such talk exists proves the Song—the rulers of the Central Plains at the time—took a far lower posture toward Goryeo than the later Ming did toward Joseon.
Why could Goryeo strut around like that? Because they crushed the Liao army that had led the mighty Battle of Tezong Pass, which reduced the Song to a Liao tributary in all but name.
And that was after Emperor Seongjong of the Khitan—moved centuries before King Seonjo of Joseon during the Imjin War—assembled his elite Usilpi Army and a full hundred thousand troops bent on destroying Goryeo, only for them to be annihilated at Gwiju.
The Song saw Goryeo—which didn't just repel the Khitan invasion but utterly wiped them out in open battle—as a partner threatening the Khitan's rear. The Gwiju Great Victory truly was astonishing. Khitan Emperor Seongjong and Commander Sobaeap of the Third Liao-Yo War were hardened conquerors, yet they got thoroughly fleeced by Kang Gamchan, a seventy-year-old civilian with no battle experience.
Sure, Goryeo's forces outnumbered the Khitan two-to-one, but excluding Kim Jongheon's ten thousand cavalry that struck their flank, most were peasant levies.
Why dredge up events from a century ago? Because Goryeo's current plight—torn apart by repeated civil wars and the military regime's abuses—is a total mess. If we stabilize the military regime now and crush the Mongols, we could revive that past glory.
Too greedy? The Mongols are already openly rampaging through Goryeo, flaunting their ambitions. Repelling them isn't optional—it's essential. Even if it seems impossible, we have to do it. The Khitan were just a preview of the Mongol army. Beating the Khitan is Goryeo's unavoidable homework.
If it really proves impossible, then yeah, I'd have to settle for being Choi U's daughter in this era, squandering away until the Mongols invade. But reincarnating here just to die pathetically? No way—that's too unfair.
At minimum, before the Mongol wars hit, we need to secure as large an army as in King Hyeonjong's era. Lay the groundwork for field battles. That means boosting birth rates and tax revenue—implement the Great Equal Tax Law, double cropping, whatever it takes.
Of course, first we need gunpowder to give us the pretext to rebuild the army.
"Milady. So how do you plan to spend those two years?"
Two years? Plenty to do. First off, my personal task is making gunpowder. Father Choi U isn't likely to jump into action just because I yap about it.
So at least, to prove the existence of that mountain spirit I mentioned, I'll set up a niter bed. And niter beds mean frying and fermenting filthy stuff. Surely I can't soil these delicate hands with that?
"Father gave me discretion, so I'll use it however I like."
Time to milk Father's indulgence a bit.
Choi U of the Inspectorate of Capital Armories had been mulling over his daughter's request for time when he summoned General Park Songbi.
"My lord, what do you mean by that?"
"Exactly what I said. Go check what that child's up to. No matter how clever she is, she's still a woman."
"My lord, Milady has never been an ordinary girl."
"Indeed, my lord. She'll lose interest soon enough anyway."
General Daejipseong, who held a post in the Inspectorate, piled on to Park Songbi's words, but Choi U shook his head.
"She's too boyish to call a proper girl, too foxy to call a boy. That's why she might wander off anywhere."
She showed zero interest in men, for one. He got that she might resent a political marriage, but she never mentioned liking any house's son or her ideal type. Even Choi U himself, the military regent, was in the dark.
"That's not what I mean. Two whole years?"
What on earth would she do for those two years?
"She called Manjong and Manjeon to play with them."
"Yes, my lord."
Choi U knew his daughter doted on her half-brothers from lowly gisaeng origins. She was so affectionate. She wouldn't waste two years. And if she truly proved something—if marriage to a man and family would only chain her—he'd keep his promise.
"A child who looks after her lowborn gisaeng-blooded brothers won't do anything suspicious. Still, just in case—attach some Byeolcho troops and watch her yourself."
"Understood, my lord."
With his daughter's matter settled, the real issue was state affairs. Jurchens raiding across the Amnok River every other day, Mongols throwing their weight around—it exhausted the Choi regime.
"My lord, the Mongols' bullying is getting worse."
"Ever since the Gangdongseong Battle, their arrogance has spiked."
The Gangdongseong Battle. As the Mongols swept aside the Jin without mercy, Khitans under Jin rule tried reviving the Liao as the Great Liao State, seizing Liaodong under Ayul Yuga. Called Dongyo, it submitted to the Mongols. Dissatisfied, some elevated Ayul Yuga's brother Ayul Sibul, ousted Yuga, and founded the Great Liao Maritime State (Huyo). But they allied with Dongjin—founded by Pusianmanuo of Jin origins—only for Dongjin to destroy Huyo.
The Huyo remnants fled into Goryeo, launching the Khitan refugee invasion. The Choi regime watched them pillage the mainland like neighbors gawking at a fire. Choi Chungheon even ignored reports of their approach.
Only after things worsened did they counterattack and push them back to Gangdongseong. Neglecting them further invited Mongol-Dongjin intervention; Goryeo allied with them to finally rout the Khitans.
From that battle, the Mongols demanded a brotherly oath, establishing formal ties. That shaky relationship devolved into Mongol bullying, with the Choi regime placating them ever since.
"Disaster will strike someday."
Choi U nodded gravely at General Jusuk's words.
What to do with these Mongols? They crushed the Jin in the north. Couldn't treat them lightly. But raised on the steppes, they demanded tribute endlessly. Dongjin, founded by Jin's Pusianmanuo, strutted trusting the Mongols. Even Jin generals acted like warlords beyond the Amnok, a headache for Goryeo.
In that mess, Mongol arrogance tested whether Goryeo—especially Choi U as Choi regent—could truly govern.
"If that mountain spirit Yeon mentioned really exists, I'd love some help."
He truly wished for the mountain spirit's aid, for the regime's stability if nothing else.
This spot up the Han River was where I'd come personally to start the niter bed. Success here means we can scale nationwide. Why make a niter bed? To replace imported soda ash for gunpowder weapons.
Too early for late Goryeo or early Joseon tech? Song and Jin had basic firearms like fire lances and rockets, even proto-landmines and grenades. Goryeo mentioned gunpowder but only weaponized it late.
Niter beds are tough initially but produce more than imports once set. From there, cannons and matchlocks are feasible—I know the basics. Can't make steel bores yet, but rifling for range? We'll see.
"Perfect. This is the spot."
Near the capital, but ample water, labor, and easy slave mobilization.
"You really mean to do this?"
I patted the grumbling slave's shoulder.
"Injun, what's impossible about it?"
"People are expendable, but for you, milady..."
What an idiot. As if I'd handle it myself.
"That's why I'm using your help. And we'll order underlings—what's the problem?"
The fool gaped. He'd followed, but never imagined I'd make him do the dirty work.
"Sure, but the stench will spread."
"That's why we pick isolated spots like this."
Site surveyed, perfect conditions met. No reason not to start now.
"I know it's not work for a lady."
"Oh? Not listening?"
This guy thought his head had grown too big for his master. Kim Injun—soon to be Kim Jun—a Choi family slave. No ordinary one. Son of Kim Yunseong, Choi Chungheon's political slave, he wielded influence among slaves.
A top-tier slave. And this Kim Injun would later change his name to Kim Jun and topple the Choi regime. By then, the Chois were doomed anyway, and he'd won over the Sambyeolcho with his grown power—but his rise from slave to military regent was no fluke.
Even my father Choi U spared him despite adultery with his concubine—proof of his favor. Or maybe Father swings that way.
"A-alright. Then mobilize the retainers."
"Recruit folks too. If locals see us making this, they'll gossip about what those Byeolcho bastards are up to."
"We can just beat the shit out of them."
Typical political slave from a military house. So violent.
"Oh yeah? Even if you're the one handling it?"
"Ugh. How many to recruit?"
"Twenty."
Being a power broker's daughter has perks.
Niter bed basics: Prepare land first. Dig pits along the river—1 meter deep, 2 meters wide—line with gravel, seal with clay for waterproofing. This riverside spot's ideal. Shovels for digging, gravel and clay easy to get.
Once dug, fill with manure, straw, ash. Animal dung works too. Pile to 80cm, sprinkle saltwater. Manure's plentiful near villages—human, beast, straw, ash, no issue.
Cover and let sit six to nine months. Summer: water and turn. Winter: pile snow for insulation. Months later, leach the soil for nitrate solution, boil and crystallize. That's saltpeter.