Chapter 34: [Battle of the Yesong River] – Part 2
[Goryeo]Shin Sung-gyeom: Cannon Unit (Arquebusiers + Cheonja Chongtong + Fire Rockets) 500Dae In-seon: Eight Banner Army 1,500
[Later Baekje]Sang-gwi: Baekje Landing Force 8,000
Dae In-seon confirmed that the entire Baekje force had disembarked at the frontline and gave a subtle signal to Shin Sung-gyeom.
The Goryeo arquebusiers, crouched low, loaded gunpowder into their barrels and tamped it down with rammers.
Once fully prepared, they aimed their guns at the charging Baekje forces.
The Baekje soldiers, initially united and confident as they marched toward Songak Fortress, sensed something was off—but by then, Shin Sung-gyeom had already given the firing command.
"Open fire!"
Bang—bang! Bang! Bang!
The arquebusiers erupted in unison, marking the beginning of battle.
Sang-gwi's Later Baekje army, unfamiliar with firearms and cannons, had no idea where the deafening thunderous sounds were coming from and halted their advance, effectively becoming test subjects for the Goryeo gunpowder units.
As Baekje soldiers, once brimming with confidence, fell to the ground at the sound of thunder, Sang-gwi quickly sent his shielded infantry forward.
But shields offered little protection against gunfire.
Bang! Bang-bang! Bang!
"What is this sound?! Our soldiers are dying!"
"General Sang-gwi! Look over there!"
General Sang-ae, accompanying Sang-gwi, spotted something spewing fire toward the Baekje army.
Sang-gwi confirmed it too, but could not comprehend what it was. All he could see was that every time these mysterious devices fired, Baekje soldiers fell in confusion and bloodied chaos.
"What is that? What on earth are those things?!"
"They are Goryeo's Samjok-o banners! That sound comes from Goryeo!"
"What trickery is this! Everyone, do not be afraid! Their numbers are few! Annihilate all those Goryeo barbarians!"
Sang-gwi rallied his troops and ordered them to charge the Goryeo army, but each time, the thunderous noises shattered Baekje morale.
Dae In-seon let Shin Sung-gyeom fire relentlessly at the Baekje forces, but to completely crush them, more was needed.
Finally trusting Shin Sung-gyeom with the cannon unit, Dae In-seon allowed him to deliver the decisive blow to break the enemy's resolve.
"Fire the mortars! Turn the Baekje invaders who dared to tread on Goryeo soil into a beehive!"
Thwack! Thwack!
Goryeo's Cheonja Chongtong cannons roared, and the Baekje army, unable to withstand even the arquebusiers, began to break formation. The sound resembled lightning striking all around, filling the enemy with fear. Cannonballs smashed limbs, and each explosion produced screams reminiscent of hell itself.
"Argh! My arm! My arm!"
"My… my leg… Mother!"
"Ah… Aaaah!"
The screams of the Baekje troops were unlike anything previously heard on any battlefield. Sang-gwi and Sang-ae memorized the horrifying scene, never wanting to set foot in war again.
But retreat was impossible. Eight thousand troops were supposed to march on Songak.
"What on earth is happening?!"
"Whatever tricks they use, the Goryeo army anticipated our approach! We must retreat!"
"How can we retreat now? With such unknown weapons! If we return to the ships now, will any of our army survive? We must crush the Goryeo army here!"
Sang-gwi and Sang-ae argued over whether to retreat, but it was already too late. Facing such weapons, even turning back to the ships would be suicidal. Surviving even a hundred would be considered luck.
"Shall we face the Goryeo army alone?!"
"There's no other way!"
"Ah! Everyone is dying! Our soldiers of Great Baekje! The emperor's soldiers are falling!"
"There is no other choice! We must overcome these thunderous Goryeo forces! Only after defeating them can we retreat!"
Everyone knew that if retreat was impossible, their only option was a final stand.
Even amidst the overwhelming defeat, a last ember of resistance remained in the Later Baekje army.
"They've stopped! Now is the time!"
"Charge! Crush the barbarian Goryeo soldiers!"
Shin Sung-gyeom's cannon unit had paused briefly to reload.
The Baekje army seized the chance to press forward, attempting to repel the Goryeo forces—but Shin Sung-gyeom still had his trump card.
"Fire the rocket!"
Whoooosh—Kaboom!
Goryeo's first rockets streaked across the night sky, raining down on the Baekje army. Though accuracy was imperfect, every explosion inflicted damage. The Baekje forces, invading Goryeo lands, found no rest or peace, only pain and collapse. Goryeo archers behind them rained further destruction, shattering the enemy completely.
Queen Jinseong of Silla and her officials watched with their own eyes, mouths agape.
"What… what is that?"
"Goryeo… are they using such formidable weapons?"
"The cruel Baekje army is suffering defeat unilaterally."
"This is truly the army of the Son of Heaven."
Such weapons had never existed before.
Thunderous, overwhelming devices that struck terror, slaughtering foes regardless of numerical superiority. Punishment for invaders delivered with precision.
Even Silla's bureaucrats, accustomed to peace and corruption, were profoundly shocked.
If the officials were awed, Queen Jinseong's reaction was even more reverential. Unlike the impassive Sul-yul-pyeong, she observed the Goryeo army as though watching the Son of Heaven himself repel enemies—her gaze filled with respect, awe, and fear.
By now, the Baekje army had been reduced significantly by the continuous bombardment.
Confident in victory, Dae In-seon immediately ordered the Eight Banner Army:
"Crush all remaining Baekje forces! We cannot allow them to scatter and harm Goryeo citizens!"
Shin Sung-gyeom ceased fire at Dae In-seon's command. The Eight Banner Army then surged forward, executing the remaining Baekje forces with precision.
Dae In-seon did not tolerate prisoners. Invaders were not to be fed or housed—he intended to utterly crush them and demonstrate Goryeo's resolve.
The battle concluded swiftly in Goryeo's favor. Blood and corpses littered the battlefield. Only a few wounded Baekje soldiers survived, groaning in pain.
Sang-gwi and Sang-ae were captured. Though young and backed by Gyeon Hwon's support, they were thoroughly defeated. Sang-gwi had lost his right arm, and Sang-ae, though unharmed physically, was paralyzed with terror.
Kneeling before Dae In-seon, they faced the young king of Goryeo.
"Are you the generals of Baekje?"
"Y-Yes…"
"I am Dae In-seon, the King of Goryeo. Tell me, how does it feel to fail a raid?"
Dae In-seon laughed mockingly, and Sang-gwi and Sang-ae stiffened, staring at the young king before them.
The men sent by Gyeon Hwon to kill Dae In-seon were powerless in his hands. Though both Sang-gwi and Sang-ae were young, Dae In-seon looked even younger—and yet he had crushed them completely.
Sang-gwi could only offer a hollow laugh, steeling his mind and raising his eyes sharply.
"Do not humiliate us further. Kill us!"
"Of course. But first, I must say something. I am truly sorry to you."
"What do you mean?"
Dae In-seon smirked.
"This entire situation—I orchestrated it. Leaving Gaegyeong seemingly vulnerable, I knew the foolish Gyeon Hwon would take the bait and come out like this."
"You… you deliberately lured us? The Baekje army?… You toyed with us?"
"Honestly, you are worse than the Heuksu Malgal or the Khitan. Hahaha! To think those who claim to avenge King Uija would be so incompetent."
In prior battles with the Heuksu Malgal and Khitan, Goryeo's forces suffered some losses. But in this first engagement with Baekje, there was none. The Baekje army, ignorant of firearms, was no match.
Sang-gwi and Sang-ae had no idea they were mere pawns in Dae In-seon's scheme. They thought the young king had simply shown weakness—but every setback was orchestrated by him. The realization sparked a burning fury in their hearts.
Now it was too late. Both were defeated, and the Baekje army annihilated.
Only the wounded survivors, deliberately left by the Eight Banner Army, remained.
"Do not humiliate us further!"
"Which of you fired the guns?"
"Kill them at once!"
"You, I suppose. Very well. Execute him."
Dae In-seon, as king, showed no mercy to those opposing Goryeo. No thought of mercy or treating the enemy as prisoners remained.
The Eight Banner Army immediately beheaded Sang-gwi. Accustomed now to the scent of blood on the battlefield, Dae In-seon coldly observed the corpse before turning to Sang-ae.
"Are you Sang-ae? Very well. You shall live. Not worth killing. I will provide you a ship—return to Wansanju with the dying Baekje soldiers. Deliver this head and my letter to Gyeon Hwon."
"H-huh… A-alright… I will obey."
Sang-ae, struck with the fear of death after Sang-gwi's execution, complied obediently.
Dae In-seon loaded the dying Baekje soldiers onto the ships without tending to them. Goryeo had no reason to treat prisoners, so this was entirely natural. Still, Goryeo's navy escorted them through Baekje's waters.
The abandoned Baekje ships were discarded like refuse, leaving Wansanju's population in panic as they gathered survivors, including Sang-ae and the remnants of the army.
News of the defeat reached Wansanju Palace, igniting Gyeon Hwon's fury.
Sang-ae, punished physically for the defeat, barely managed to deliver Dae In-seon's letter to Neunghwan. Baekje recovered only Sang-gwi's severed head.
Neunghwan clenched his fists in anger and immediately convened a council with Gyeon Hwon to discuss measures against Goryeo's southward advance.
The council began with the scathing insult Dae In-seon had written to Gyeon Hwon:
"Self-proclaimed King of Baekje, Gyeon Hwon. I have received your 'gift' well. Your troops at the Yesong River served as test subjects for my new weapons—very satisfactory. Therefore, I order you: if you wish to avoid seeing Wansanju reduced to ashes, personally come to Gaegyeong, bow your head, and surrender your kingdom. If not, Wansanju will burn, and your entire clan shall be annihilated."
The provocative letter was written in Goguryeo script, mocking Gyeon Hwon as if he had insulted Dae In-seon as a barbarian.
Infuriated, Gyeon Hwon ground his teeth and threw the letters sent by Dae In-seon aside.