Instead of Self-Propelled Artillery, Knight Cannon

In the medieval era, prisoners of war had no concept of human rights.

If a prisoner had no value, it was common for them to be tortured and starved to death.

Fortunately, this romance fantasy world had a much better grasp of human rights compared to Earth's Middle Ages.

Usually, it's commoner soldiers or fallen knights who suffer such inhumane treatment. But in this world, even commoners can rise to become knights or mages if they have talent in mana. That's why concepts of human rights took root earlier here.

Walking down to the temporary prison set up in the basement of the Karon lord's castle.

"It's ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠not as gloomy as I thought."

"Yes. It was originally used as a food storage room."

As I reached the prison entrance, two royal soldiers standing guard snapped to attention and saluted.

"Your Highness! You are here!"

"Good work. Open the door. How are the prisoners doing?"

"Thank you! The prisoners are disarmed and detained quietly. Some occasionally shout for more food, but they don't seem to have any intention of resisting."

The soldiers said this ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠and pushed open the iron door.

Kiiiiik.

As I stepped inside, a rank smell of sweat hit me, and I saw dozens of Empire soldiers huddled inside the iron bars.

'They're nervous.'

The eyes that lifted at the sound of the door opening were deeply etched with defeat, fear, and anxiety.

Elisa brought a chair from somewhere, and I sat down.

"How's everyone doing?"

My casual greeting was met with silence. Instead, a black-haired female knight, who seemed to represent the prisoners, slowly approached me.

"Stop right there."

"It's fine."

Elisa tried to block her, but I raised a hand to stop her.

The black-haired female knight stopped right in front of the bars. Her eyes betrayed her anxiety, but she still held onto her knightly pride.

"I am Seria, Vice-Commander of the Imperial Army's Karon Garrison."

She introduced herself as Seria with a stiff, knightly posture.

"Right. I'm Ian Espada."

At my casual response, her eyes wavered before she steeled herself and spoke.

"Prince Ian... what do you intend to do with us? If we are to suffer a knight's dishonor, please grant us the right to take our own lives."

'Oh... she looks just like a certain female knight.'

I wanted to drag it out a bit more.

"Well, I was thinking of ransoming you back to the Empire..."

But at the mention of being sent back, Seria looked more shaken, not relieved.

Just as I thought, they're not welcome back in the Empire.

"You don't want to go back to the Empire."

"That's..." She took a breath before continuing. "...Yes. You're right. Our unit was politically purged and demoted. Most of us are commoners or fallen nobles. So, even if we returned to the Empire, we wouldn't be treated well. The Empire... is not kind to defeated soldiers."

She spoke with a bitter expression. The knights sitting behind her also looked gloomy.

'So they have nowhere to go.'

This is actually good for the Kingdom. If they have no attachment to the Empire, it means I can turn them into loyal subordinates, as long as I treat them well here.

'The Kingdom is short on manpower.'

"That works out perfectly."

"...Yes?"

‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠

Seria looked dumbfounded. She was clearly confused that I thought her hopeless situation was good for me.

"If you have nowhere to go, just live here."

"...Yes? You mean you'll take in prisoners from the enemy nation?"

"Something like that. Of course, I don't plan to work you for free." I stood up and walked a step closer to the iron bars. "The Espada Kingdom is very short on knights. I'd like you to fill those spots. Ah, of course, you'll have to take the Oath of Mana."

The Oath of Mana is a vow made on one's own mana, binding them to specific conditions. If the oath is broken, their mana runs rampant and they die instantly. It's an absolute contract.

In their position, it's the same as handing over their lives as collateral. It might seem harsh, but I can't just integrate enemy prisoners into my army without any safeguards.

"Choose. Start a new life by swearing the Oath of Mana, or go back to the Empire."

At this, Seria looked conflicted, then soon knelt on one knee as if she had made up her mind.

"...We are knights who have already been abandoned by our lord. If you take us in, we will dedicate our lives to serving you. ...I will swear the Oath of Mana."

At her words, the other knights who were huddled also straightened up and knelt on one knee.

'What? Acks?'

The name 'Acks' belongs to the leader of the Imperial Revolutionary Army, a villain who appears in the latter half of the original novel.

'I'm pretty sure Acks was a soldier too.' The novel only mentioned that he was from a fallen noble family and never used the name Seria.

'The description matches perfectly.'

Long black hair, black eyes. A former knight with a rigid way of speaking. And the name Acks. 'Though there's no scar on her face.'

In the original, Acks of the Revolutionary Army lost all his subordinates after being abandoned by a corrupt commander. He then founded the Revolutionary Army out of disillusionment with the Empire.

'My recapture of Karon changed the future.' In the original timeline, all her subordinates would have been killed by Count Kelrn, who was in league with the Black Wizards. But now, she and her surviving subordinates are kneeling before me.

As I was lost in thought,

"My lord?"

I saw them all kneeling, staring at me blankly. The oaths must have been completed. 'Their eyes got softer as soon as they swore the oath.'

"Good. I'm counting on you. But aren't you upset that we basically killed your comrades?"

Seria shook her head at my blunt question. "It is only natural for knights to lose their lives on the battlefield. They were prepared for it, so there is no resentment."

Her voice was unwavering. The other knights kneeling behind her nodded in agreement.

Is this what chivalry is? I nodded and turned around to give Elisa an order. "Elisa. Contact the kitchen and tell them to prepare plenty of bread and stew with lots of meat. Everyone must be very hungry."

"Yes, my lord."

After asking Elisa to arrange the meal, I left the basement.

'Now that our forces have increased, I should try something new.'

Originally, my next plan was to build the flower of modern warfare: the tank.

But as I was planning it out...

'Not easy.'

Building a tank required a lot of foundational technology. Like armor plating that could withstand enemy attacks and an engine strong enough to move that heavy armor. Mana stones could cover some of it, but...

'The firepower of a self-propelled gun is hard to achieve with just mana stones.' More precisely, it wasn't cost-effective. For that much money, I could just train more knights.

I can't even imagine how many mana stones would be needed for a single self-propelled gun.

And repairing it if it broke or was destroyed would be a huge headache.

So I thought about using the 'tanks' of this world instead: the knights. But the Kingdom was severely lacking in knights.

So much so that most of the knights who participated in the recapture of Karon just a few days ago had already departed for key strategic locations across the kingdom.

Just as I was stuck in this dilemma, we got exactly 53 new knights. And they ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠were knights with 100% loyalty, bound by the Oath of Mana! I could finally fulfill my dream... I mean, execute my plan.

The basic form of the planned weapon was a lance. Since it's a weapon knights are already familiar with, it should be easy for them to adapt. I'd load it with gunpowder mixed with a small amount of mana stone powder, similar to the muskets, and make the bullet explode at point-blank range. The inside of the thick lance shaft would be hollowed out like a cannon barrel. A trigger mechanism would be installed near the grip. It would pierce the enemy's armor or aura with its tip, then fire a shell at point-blank range. A brutally violent weapon. Its name? The Gunlance!

Besides, since it would only be issued to knights, inscribing a lighten enchantment on it would be cost-effective. Without a lighten enchantment, the weight of the weapon would prevent the horses from moving. I could also inscribe various other enchantments on it.

"Heheh..."

A smile crept onto my face at the thought of a Gunlance unit decimating the enemy.

While designing the Gunlance, I briefly considered a beam cannon. But a beam cannon requires even more massive thermal energy than a Gunlance. Besides, as a directed energy weapon, it would be impractical for a knight to use. Knights fight by enveloping themselves in aura. Using a directed energy weapon like a beam cannon could destabilize their aura. A beam cannon would be more suited for a mage. 'I'll think about that later.'

Lost in thought, I soon arrived at the workshop. Karon also had a smelting facility and a blacksmith's forge that the Imperial army had used. It must have been built by Count Kelrn to repair and supply weapons. Thanks to that, I was saved the trouble of having to build the infrastructure from scratch.

'Originally, the Karon territory was a barren countryside with only castle walls and a mill.'

Kiiiiik.

As I pushed open the iron door and stepped inside, a wave of scorching heat hit me.

"Your Highness! You are here!"

The blacksmiths, who had been waiting after receiving word from Elisa, wiped their sweat and bowed in unison.

"Good to see you. It's better maintained than I thought."

"Yes! It seems the Imperial bastards were using it until recently."

I nodded at his answer and immediately walked to the workbench, spreading out the blueprints for the Gunlance that I had in my arms.

'Finally making this thing.'