The Final Pursuit (Part 5)
The reason behind the precision of the cannon fire was simple: it was all thanks to Yi I.
Back at the Han River, I had watched in disgust as precious gunpowder was wasted on shots that hit nothing but empty air. That single glance sparked something far greater than mere irritation. It ignited a relentless curiosity that pulled me deeper into the realm of science than I had ever imagined possible. And with the king’s support flowing freely, my knowledge accumulated at a pace that still left me breathless.
Thanks to that obsession and royal backing, Joseon’s scientific and weapons-manufacturing capabilities—along with the entire industrial network they supported—were soaring higher than anyone could have predicted. With that foundation, I created the steel cannon lined with dragon-scale engraving. I heated a massive chunk of manganese-alloy steel until it glowed cherry-red, then connected it to a steam engine and pounded it with an enormous iron rammer to shape the barrel. After mounting it on a massive lathe, I used various drill bits to carve the surface, drilling perfect holes for the charge. The resulting cannon was terrifyingly effective. Thanks to the dragon-scale, it spun and flew true, never veering off course, and its maximum range exceeded ten kilometers.
That range, however, created its own problem. If the shells could fly beyond visual range, who knew where they would land? That uncertainty forced me to collaborate with Kim Ji. Together we developed the new fused cannonball that eliminated stray shots, and we refined the charge system as well. Close range used one charge, medium range two, and anything over ten kilometers used three. We even charted the exact ranges for every possible angle and charge combination through repeated trials. I would fire a cannon toward the sea, calculate the precise distance using triangulation between the impact point and a pre-marked reference, and record the data in a neat table. Now our gunners no longer needed to do the math themselves. They could simply glance at the tables and fire with perfect confidence.
Yet I was not finished. The method was faster and simpler than calculation, but we still needed to measure angles manually because we could not attach a proper level made of glass to the cannon. That extra step wasted too much time. To solve it once and for all, I invented something even more elegant: the gunners’ quadrant. I took a long rule, inserted it into the muzzle, and attached a long sighting rod at the end. Then I added a semi-circular arc that slid along the rod. By simply sliding the arc into perfect horizontal alignment with the sighting rod, the gunner could read the exact range from the single mark where the plumb line intersected the arc—no tables, no calculations, nothing. I placed this “range semicircle” on the third prototype of the new ship, right beside the cannon. Yet for some reason I never used it in battle.
The reason was simple. I had already tested the same thickness of cordite, weighed the charges exactly, and confirmed they were consistent. But I had never performed enough live-fire trials to be absolutely certain. I refused to waste even one cannonball, and I feared that a single stray shot landing among our own troops could trigger a disaster. So I gave the order: only fire in support when the signal of our army falling back was received. But then I had to smile when I saw the long streak of fire that had just crossed the sky like a drawn line of lightning. “As expected, Sun-shin.” I had told Jeong Geol and Yi Sun-sin before leaving the third prototype: if the enemy launches a massive assault, use the cannons to finish confirmed targets immediately. Protect our own troops at all costs. Even now, watching those still-burning flames, I could almost see Sun-shin carrying out the order. Jeong Geol was only acting as temporary captain, after all; he would not have interfered with the cannon fire himself.
Dawn was breaking by the time the noise of the Joseon Eastern Army camp finally erupted. The once-silent encampment had become a storm of shouting and running feet.
“Looks like they’re finally leaving,” I muttered, turning to Ukita Naoie, the man I had appointed commander of the Eastern Army. “Once the battle is over, wait for full daylight, then pursue and annihilate every last enemy.” I gave him that promise with a smile, knowing full well what I was really ordering.
Of course Ukita Naoie understood the hidden meaning. His face twisted with barely contained rage as he began screaming at his soldiers like a man possessed.
“You damn fools! What the hell are you doing standing around like that?!”
Ukita Naoie had already weeded out every last vassal of Mori Motonari once he took command of the Eastern Army. In this world where betrayal and coups were as common as breakfast, he had still feared a revolt among the loyalists. So he filled the ranks with the men he himself had brought from Japan. When the other daimyo who had come to serve the king offered them positions, Ukita Naoie cut them off with a single cold word: “Do you really think I would trust you?”
He had been lucky to land on the strong back of Joseon, but he had no achievements of his own yet. And after years of witnessing betrayal and coups every day, he trusted no one but the king and the vassals who had fought beside him. “Listen well! The king said that once the war ends, he will grant land to all of you. Now move your asses and chase these bastards down!”
But the soldiers did not believe a word of it. They had never heard of a daimyo giving land to low-ranking ashigaru like themselves. Enrolling as a vassal or a samurai retainer was one thing; actually receiving farmland from a lord was unheard of. And with the constant changing of regional lords and tax rates, they had never even owned land in the first place. So they dismissed the order as empty talk. Yet they still hurried to grab their weapons and move out. They had been well fed by the Joseon army and had been promised extra rations. Staying in the Eastern Army was clearly the better option. Zenjiro and Saburo ate their fist-sized rice balls while walking together and began chatting.“Saburo, I didn’t sleep a wink last night.”“Same here. I was too scared to close my eyes.”“By the way, how much gunpowder do you think the Joseon army has?”“Who knows?”“Last night, after the sky darkened, we both collapsed into deep sleep after eating. Two days of the enemy’s relentless assaults had left us completely exhausted. Then, in the middle of the night, the cannons roared. It was a sound that made the world feel like it was collapsing. I jumped up in alarm, but there was nothing I could do. Ukita’s orders were clear: do not move without permission, stand by and wait. That waiting was worse than any battle. In the dark I would have slipped away if we had to fight. But the camp guards were everywhere, and even going to relieve myself felt impossible. Now I thought I was finished. Then the call-up horn suddenly blared. ‘They’re coming!’ Both of us grabbed our bows and sprinted toward the barricade. Better to die fighting than to be cut down by samurai blades. Then, from the south, came a series of explosions followed by flames. With regular intervals the blasts rippled out, fire spread in every direction, and the screams of dying men tore through the night. The entire sky became an inferno as the remaining straw of the harvest and the tall reeds burned to ash. Zenjiro and Saburo stood frozen, bows still in hand, watching in stunned silence. There was no order to pursue, but even if there had been, the flames were too fierce to approach.“When the battle was finally over, we heard the order to begin the pursuit. We hurried to join the pursuit formation. Along the way we saw nothing but the enemy’s corpses. It was almost a mercy. Most of them had fallen without their armor damaged, so the weapons they carried were still intact. That only made the loss feel worse. If the battlefield cleanup crew had been there, they would have taken everything. Yet the number of bodies with shot-pierced armor made me think of something else.“Saburo, do you think this armor actually stops arrows and gunshots?”“We already tested it, didn’t we?”“But the ones they gave us might be inferior.”“Probably.”“The Joseon army handed out armor that looked like paper. It was feather-light, yet they claimed it could stop gunshots and arrows perfectly. They even let us try it ourselves, firing their own cannons and bows to prove it. And the armor they wore was identical. It sounded ridiculous—how could something so light be as effective as the heavy samurai armor we knew? I had never seen a single enemy wear anything like it in my life. Even the Mori clan’s forces had worn different armor depending on whether they followed the lord or their own vassals. Still, I was curious. “Saburo, try stabbing me with an arrow.”“What if I hurt you?”“We should at least test it.”“Fine.” Saburo pulled an arrow and drove it straight into Zenjiro’s back with a sharp ‘thwack’. The armor did not penetrate. Only a tiny mark appeared. “Harder!” “Okay.” This time I put more force behind it. Same result. Zenjiro staggered slightly from the impact. “You okay?”“I’m fine. Hit me harder.” “Alright!” This time I aimed to break the arrow itself. Still no penetration. Only a deeper bruise. “Wow, that’s really something.”“Any holes?”“No, none. There are scratches, but no actual holes.”“The other soldiers saw what we were doing and copied us. One grabbed a pocket knife and scraped the armor. Only a thin line appeared; the material was unbreakable. “Damn! Even a sword won’t go through!” “Really?”“It’s true. Look at this.”“Whoa, it really is.” The soldiers who had heard the tales of the armor made from chicken feathers and eggshells began whispering among themselves. But then the samurai appeared. “You damn brats! What the hell are you arguing about?!” “Thinking this is a playground?!” “Can’t you keep your mouths shut?!” “Going crazy from wanting to die?!” The samurai drew their swords and yelled, but it was useless. The soldiers, thinking their lives were on the line, simply shouted louder. The samurai finally sheathed their blades and gave up. I was glad they understood. Some even tried the armor on themselves while marching. Their morale never stopped climbing higher. No more straw armor for them—real armor that could stop arrows. They walked faster and closed the distance to the fleeing enemy soldiers. * * * On the ridge above the valley, Oda Nobunaga let out a long sigh. “What a mad plan…” The Oda family, handed the mantle of leadership in a moment of chaos, was nothing compared to the other great houses. Their soldiers were weaker than those of neighboring daimyo, and his own strength was nothing like Takeda Shingen or Uesugi Kenshin. Yet he had seized Owari and taken Kyoto with nothing but the new arquebus. And now he was trying to defeat a superior firearm-armed Joseon? “What do I do?” After hearing Mori Motonari’s words, he had realized he could not win alone. So he had gathered every daimyo who was still fighting him and promised to split the giant meal that was Joseon. It had seemed reasonable at the time. They had trained large arquebus units and fought many battles. When their numbers were inferior, they always lost. So pushing forward with overwhelming force should have worked. But it had ended in utter ruin. “Damn it!” Oda Nobunaga bit his bleeding lip until it bled. The great merchant of the world had vanished before his eyes. Now he was the hunted. “How in the world does Joseon have weapons like that?” From a distance he could not see the battle clearly, but the massive flames that had erupted at the end still gave him chills. “Is Hideyoshi still alive?” He had sent him to attack the mountain where the king of Joseon was supposedly hiding. But he had died without even reaching the foot of the mountain. No flames had risen near the peak. “Ieyasu ran away, obviously.” He had ordered a clear attack on the western side, but the young and timid Ieyasu had surely fled. What about Shingen and Kenshin and Hojo? He hoped they were all dead. He knew only Mori Motonari had incited this war. If any of them were still alive… “I will be humiliated…” They would know he had planned the strategy and blame him for the defeat. “Hah…” He did not want to bear that responsibility. So many soldiers had died. The entire world was falling into Joseon hands. “Should I just commit seppuku?” He had never become a true merchant, but at least he could die a warrior and leave a name behind. But then—boom! The lights he had watched countless times on the previous night suddenly exploded across the sky. The scouting party that had been ahead of him came sprinting back. “Lord! Big trouble!” “What is it?” “The Joseon army has formed a line ahead.” “What?!” “The enemy… the enemy is right there…” The vassal could not finish his sentence. His lord, Oda Nobunaga, had fainted and fallen from his horse. * * *