Naval Cannon (3)
We loaded the 155mm cannons and all the different types of shells, then moved locations.
After a short march, we arrived at a long-abandoned quarry at the foot of the mountains behind the eastern port, left idle for years after the resources there had been exhausted.
The thunder of a cannon shot was unimaginably loud.
Even for a test, firing it out over the open ocean would panic any nearby ships or the citizens living along the coast — that was obvious.
"Set it down here. Fix the muzzle toward that cliff face over there."
"Yes, my lord! Everyone, handle it carefully!"
"Yes sir!"
"Only those who can use mana should get close!"
At my order, Seria and the workers carefully unloaded the SI-06 from the wagon.
Then, using the direction-adjustment crank, they angled the rifled cannon's barrel toward a distant rock wall.
"Alright. Grab one of these each. If you don't wear earplugs, you'll be hearing ringing for the rest of the day."
I pulled out the leather earplugs I'd prepared beforehand and handed them out.
"Cover your ears tightly and tie the strings. And when I signal that we're firing, it's best to keep your mouth slightly open. Otherwise your eardrums might burst."
At my warning, the blacksmiths and workers hurriedly put on the leather earplugs.
Except for me and Seria, they were already wearing protective helmets, so I didn't bother mentioning that.
"Seria. Let's put ours on too."
"Yes, my lord."
We donned our helmets. After confirming everyone was properly equipped, I walked up behind the cannon.
"Watch carefully how I load it."
"Yes, sir! Understood."
—Click.
I turned the breech screw to open it for loading the shell.
There's nothing quite like the sound of parts I cut myself meshing together with zero tolerance.
I pushed the most basic type of shell into the open chamber.
I would have loved to make high-explosive shells, but since I hadn't yet developed a high-performance explosive, I had to make do with explosive shells packed full of black powder mixed with magic stone dust.
Next, I inserted the propellant charge and sealed the breech tightly.
"You load it like this… then close it. That's it. Make absolutely sure it's sealed properly all the way."
The blacksmiths nodded, concentrating intently so as not to miss a single movement.
"Got it? Then I'm actually firing now."
I gripped the firing mechanism — which served as the trigger — and shouted.
"One more time: press those earplugs tight and open your mouths!"
I glanced at the cliff face far in the distance, then pulled the firing mechanism without hesitation.
"Fire."
—BLOOOOOM!!
The moment the shell left the barrel, the entire quarry shook as if an earthquake had struck.
A colossal plume of flame and gray-white gun smoke erupted from the muzzle of the SI-06.
The barrel recoiled from the blast, but fortunately the recoil-control magic circle I'd engraved into the mount absorbed the shock without issue.
The shell shot from the muzzle tore through the air, and then —
—CRASH! KABOOOOOM!!
It struck the exact center of the cliff face at the far end of the quarry and detonated.
The gunpowder packed inside the shell burst, brutally blasting apart the surface of the rock wall that had seemed utterly indestructible.
Dust and gun smoke from the explosion blanketed the quarry.
"……!"
"Wh-what the hell…"
"What in the world…!"
The dust and smoke filling the quarry slowly began to clear with the sea breeze.
And the sight revealed beyond it made the men's jaws drop as if unhinged.
"Th-that… the whole mountainside is just gone, isn't it?!"
"I've spent my life hammering metal, but I swear I've never seen a weapon that brute-strong in my life!"
"What kind of sorcery did you work, Your Highness…!"
The head blacksmith and the workers pointed at the cliff face with trembling hands, unable to believe what they were seeing.
The limestone cliff of the quarry now bore a massive crater, as if a giant had punched it.
Even Seria, standing beside me, seemed unable to hide her shock at the weapon's power.
"My lord… this is truly incredible. With this level of firepower, no matter how many ships the Imperial fleet sends, we could blast through them in an instant."
"Oh yeah? Want to try blocking one, Seria?"
"…What?"
At my playful remark, her face went white as a sheet.
"M-my lord… please, don't make terrifying jokes like that, even in jest… I am not Lady Roxanna…"
"Just kidding, just kidding."
"Hah… you startled me."
As a Sword Expert, it would be far easier and faster for her to dodge than to try to block it anyway.
But what if Seria was willing to die?
An upper-tier Expert might be able to concentrate their aura to a single point and somehow endure it.
Roxanna could probably block it without too much trouble.
During the musket test, Roxanna held back to the level of an Aura User.
Anyway, the test went well enough to call it a success.
The next morning.
Yesterday's test had been a success.
The explosive yield was exactly as expected, and after firing a few more rounds, no particular problems had surfaced.
The task now was mass production — and lots of it.
Mass-producing the components fell to the blacksmiths, but engraving the necessary magic circles onto them was the mages' job.
I'd brought in as many royal mages as possible.
The moment I stepped into the workshop, the relentless clang of hammer on metal filled my ears.
But woven into that cacophony, I heard some very familiar groans of suffering.
"Uuugh…"
"Please, kill me… I can't drink another mana potion…"
"Kyaaaaaah…"
In one corner of the workbench, several dozen mages drafted from the Royal Mage Corps were sprawled all over the floor.
They'd arrived just yesterday afternoon, yet their faces were already lined with dark circles as if they'd been up for days straight.
Well, that figures. Every mage in this world is basically a grad student.
I'd lured the mages here with the promise of research funding.
The Mage Corps Commander seemed to have sent only the rank-and-file, citing the need to defend the capital.
I approached the mage who looked most senior.
"You've all been working hard since early. How's the progress?"
"Y-your Highness…"
"How far along are you? We need to meet the quota before the Imperial fleet arrives."
"As of now… we've finished engraving the recoil-control magic circle on fifty barrels. For the shells… we've completed about two thousand with the magic circles…"
"Oh, that's incredibly fast."
That quantity in just two days.
"It is only thanks to Your Highness's promise… to double our research funding… hngh… If the funding goes up, I can only do research when I get back… please, I beg you, let me close my eyes for just a few days…"
The senior mage muttered tearfully, and I felt my resolve soften.
But I couldn't give them rest now.
…Unfortunately, there was still work to do.
"To manage that much in two days — you really are the Royal Mage Corps. Good work."
"Th-then, Your Highness… may we now get some sleep…?"
"Hmm. Sorry, but there's no time for that. Actually, I came to the workshop for another reason."
"Yes…?"
At my words, the shoulders of every mage at work flinched in unison.
"Think about it for a second. The Imperial Navy's ships are bound to have combat mages on board, right?"
"Yes… given the scale of their fleet, a considerable number of mages will be deployed."
"Right. And they're not idiots; they won't just sit there and watch our shells fly at them. They could block them with reflection magic or slow magic."
"That is… certainly true."
The senior mage nodded as if I had a point.
"Exactly. We've gone and built these wonderful weapons, and our mages have worked hard to engrave the magic circles. But wouldn't it be a shame if we couldn't even hit the enemy with them? So I was thinking about it carefully last night."
As I said this, I spread the blueprints I'd brought onto the workbench.
"What if we don't make the shell explode only after it hits the ship — but rather at the moment we want? For example, right above the enemy vessel, or in the air just before the deck. What do you think?"
"In the air… you say, Your Highness?"
"Yeah. Think of it as a kind of remote detonation device."
The principle was similar to how I communicated with Seria and the other knights through our Mana Vow.
"It would be… mana resonance."
"Correct. I see you know your stuff."
He dry-washed his face with trembling hands.
"A-a brilliant idea, Your Highness. If we detonate the shells above the enemy ships… the Imperial mages won't be able to block them all."
"Right? Maintaining a barrier consumes an enormous amount of mana."
The reason barriers consume so much mana is that, unlike reflection magic, which is a single-use spell, barriers are sustained magic.
And while slow magic is also sustained, it only requires as much mana as the weight of the shell. Defensive barrier spells, on the other hand, demand mana equivalent to the explosive yield.
And for a weapon with the explosive force of the SI-06, it would take even more mana.
They couldn't just brute-force a barrier.
"B-but, Your Highness…"
"Hm?"
"Does this mean… we have to engrave this new magic circle onto all two thousand shells we've already completed?"
"Yeah. That's right. And of course, all the shells we make from now on will need it too."
The very moment I finished speaking, screams erupted from a corner of the workshop.
"Gyah…! I quit being a mage! Send me home!"
"WAAAAAHHH!!"
"Don't worry, I brought plenty of mana potions. And I'll be pulling all-nighters with you, so let's all give it our best."
An all-nighter had begun.