The next day, the Gyeongsang Right Naval Station and Japanese fleet encountered Joseon’s combined fleet.

Though the combined fleet’s size had decreased by 10 ships after removing those needing major repairs, their morale remained high.

Seeing Joseon’s large, imposing warships, the Japanese examined their own vessels. Their reactions to comparing their ships with Joseon’s vessels split into two groups.

“They said the tribute ships[1] were large too…”

“Every time I see them, I feel that Joseon ships look so sturdy.”

Though the tribute ships were larger than their previous vessels, they still paled in comparison to Joseon’s warships.

While some Japanese – mostly under the Ouchi clan – reflected on this with self-criticism, those who had lived turned away from the outside world engaged in mental gymnastics.

“Why do they need such big ships? The sea between Joseon and Japan is so narrow! And it’s the same with the sea between Ming and Joseon – it’s tiny! This is wasteful! Pure waste!”

“Looking at that size, they must move sluggishly! A proper warship should be fast and agile! That’s how you quickly attach to enemy ships and engage in hand-to-hand combat!”

“That’s right! Hand-to-hand combat is supreme! Whatever anyone says, Japanese ships are the best in these seas!”

Watching their fellow Japanese insist that their ships were superior in the seas between Joseon, Ming, and Japan, the Ouchi clan samurai wore expressions of disdain.

The previous lord called them frogs in a well, and he was exactly right.

They don’t know how naval warfare has evolved, and they don’t want to know.

As the Ouchi samurai thought, naval battles had already shifted from boarding and hand-to-hand combat to artillery exchanges.

But these provincials before them, rather than admitting their backwardness, still insisted that hand-to-hand combat was supreme. This despite having experienced the power of artillery at the Battle of Jinpo in late Goryeo.

However, even these Japanese who stubbornly insisted on their superiority fell silent when the Maengjin passed before them.

“What kind of ship is that…”

“Is that a ship or a monster?”

This was true even for Norihiro aboard the Gyeongsang Right Naval Commander’s ship.

“Was that truly made by human hands?”

“Of course it was made by human hands.”

“How could such an enormous ship…”

While Norihiro was expressing repeated admiration, the elderly samurai beside him was struck with terror.

How can such a massive ship float normally! What kind of timber did they use for the keel!

***

Just before departing, Mochiyo had given Kuroda a secret mission.

“Kuroda, since you’re familiar with ships, board the Joseon warships and examine them carefully.”

“Hai!”

And Kuroda faithfully followed his orders. While appearing to look around the Challenger-class vessel like a provincial sightseeing Hanseong for the first time, he was internally analyzing everything to the best of his ability.

Hmm… so this is the structure… but would cedar work?

The main material for Japanese ships was cedar. With its tall, straight growth characteristics, it was the most commonly used material for building both houses and ships in Japan.

However, cedar was quite soft wood, so Kuroda was quite skeptical.

The Maengjin passing before Kuroda’s eyes was an existence that completely shattered all his existing concepts.

***

While still unable to contain his shock at seeing the Maengjin, Kuroda fell into panic listening to the conversation between Norihiro and the Gyeongsang Right Naval Commander.

“The ship looks truly sturdy.”

“You have quite the keen eye. That ship isn’t just an ordinary vessel – not only the hull, but even the roof is covered in iron.”

“Truly iron?”

“Indeed. Iron, and high-quality steel at that.”

“How in the world is it made?”

At Norihiro’s question, the commander shrugged his shoulders.

“I’m just a sailor, what would I know? I can only say that the Crown Prince accomplished something great.”

“Ah…”

When the commander mentioned Hyang, Norihiro nodded with a face of sudden understanding.

Rumors about Hyang had already spread widely even to the Ouchi clan.

As the commander said, Hyang had played a part in creating the Maengjin, or rather the Assault Turtle Ship.

However, looking at the reality, it was created through the blood, sweat, and tears of Korean researchers at the research institute starting with Lee Soonji and the craftsmen of Area 51.

***

Around the time steam engines were becoming established, starting with the iron horse, Hyang gathered researchers including Lee Soonji and shipbuilding craftsmen from Area 51.

“As surrounding countries are arming themselves with increasingly powerful artillery, we need a warship that can lead our navy and crush enemy formations while protected by sturdy armor. So I have something in mind…”

At Hyang’s words, the researchers and craftsmen all nodded. As craftsmen of Area 51, which was core to national defense, they were well aware of information about other countries’ weapons. The research institute’s researchers were similar, so they could immediately understand what Hyang meant.

Seeing their response, Hyang unrolled a large paper scroll on the desk.

“Oh?”

“An Assault Turtle Ship…”

“Mount a heavy gun in the bow, double hull with iron armor, and iron armor on the roof too? Then what about sails?”

“Moving by steam engine alone…”

The craftsmen and researchers muttered discussions upon seeing Hyang’s design. As the debate continued, Lee Soonji asked Hyang:

“It’s certain that building it according to Your Highness’s design would create an extremely powerful warship. However, there is one problem. There are no measurements for the crucial components that must be recorded. Without these, we can’t even know if success is possible.”

“That’s why I gathered all of you. Start working out those details now.”

“What?”

Hyang’s patent response, continuing from the 21st century, had emerged.

I’m liberal arts – you science people need to handle that part.

***

Though Hyang said to consider the possibilities, Hyang was the Crown Prince. Additionally, Hyang’s track record of proposing these seemingly impossible ideas was an issue. Hyang was the one who had actually created things others considered mere delusions.

In the end, for the researchers and craftsmen, it was like being told “you must succeed.”

Apart from Lee Soonji and a few other monsters who were excited about the calculations, most of the development team sighed deeply.

“Sigh~. We have to do it but… there are countless problems.”

The biggest problem was the minimum performance requirements Hyang had written down.

• Install the large-caliber cannon currently under performance testing in the bow.
• Minimum 80 guns to be mounted on port and starboard sides.
• Minimum thickness of steel armor plate protecting the hull: 1 chi 6 bu (about 5cm).

To satisfy these requirements while creating a warship that could properly float and move, the researchers and craftsmen had to work like madmen.

A prime example was the Maengjin’s keel.

The central keel length excluding bow and stern sections was 25 jang (about 75m). The length was incredible, but even more terrifying was the fact that this keel was a single steel structure.

“With a heavy gun in the bow and minimum 80 guns mounted on both sides, plus moving by steam engine alone without sails means we need an enormous steam engine…”

“There’s also the condition that the gun decks on both sides must be arranged in two levels.”

“Then it needs to be at least 25 jang. So the problem is the keel.”

The researchers and craftsmen repeatedly agonized over solving this issue.

Wooden keels were excluded from the start due to the enormous weight of all the equipment to be loaded, including the steam engine.

“It needs to be steel but… joining two or three pieces…”

At Lee Soonji’s words, all the craftsmen shook their heads.

The problem was that this was absolutely impossible with Joseon’s current welding technology. Even using their most familiar method of riveting, they weren’t confident it would hold.

In the end, the only answer was to produce a massive steel beam 25 jang in length.

The iron armor plates were also an issue. The development team, feeling uneasy about joining them to existing wooden ribs, changed the design to alternately attach iron and wooden ribs to the keel.

They adopted a method where iron armor plates would be joined to the iron ribs, while wooden planking would be attached to the wooden ribs to further enhance the hull’s buoyancy.

Taking this approach necessitated at least a 25-jang length steel beam for the keel, steel ribs that would connect to this keel and support the iron armor plates, and steel plates with minimum thickness of 1 chi 6 bu and minimum dimensions of 2 jang length by 1 jang width.

And at the Anju ironworks that took on this task, wails of despair echoed.

The project continued with the background music of such wails emanating from related departments.

The development team, having calculated the most feasible measurements, produced a 1/10 scale model ship. It was an ultra-precise model where even the rivets securing the armor were scaled down to 1/10 and used in the same quantities as would be needed for the actual ship.

After confirming the test results of this model ship, the development team reported to Hyang.

“We can build it exactly as you wish!”

Thus was born the Assault Turtle Ship Maengjin.

In hindsight, through this reckless challenge, Joseon’s technology made another great leap forward.

***

While the Japanese fleet and Joseon navy were moving toward the Shandong Peninsula, sad news reached Emperor Xuande in Beijing.

“Defeat! Our Ming fleet was defeated by the Joseon fleet! And nearly annihilated? Is this true!”

As Emperor Xuande picked up the battle report and asked again with a bewildered face, the Minister of War and the Left and Right Commanders prostrated themselves and cried out:

“Your Majesty! Please execute us!”

“Why did we lose! We had more ships! And not just more in number, but more ships armed with artillery! Why exactly did we lose!”

At Emperor Xuande’s words, the Right Commander carefully answered.

“The soldiers who returned on surviving ships say that Joseon unleashed a Black Flame Dragon.”

“Black Flame Dragon? What nonsense is this! Are they using such absurdities as excuses for defeat!”

At Emperor Xuande’s rebuke, the Minister of War carefully explained while watching the emperor’s expression.

“We too were bewildered and questioned them in detail. It appears Joseon has created a warship powered by steam engine.”

“Steam engine?”

When the Minister of War mentioned steam engines, Emperor Xuande suppressed his anger.

We too are attempting to mount steam engines on ships, and Joseon, who created steam engines before us, could certainly do it.

“Sigh~. We were one step too late.”

Having somewhat calmed his anger with a long sigh, Emperor Xuande sought to understand the situation in more detail.

“What happened to Wu Qiming who commanded the fleet?”

“He died in battle.”

“He didn’t die while fleeing?”

“No, Your Majesty.”

“Then we’ve truly lost a regrettable person. With the fleet suffering catastrophic damage, I’m worried about what follows. Have countermeasures been established?”

“We’ve strengthened the defenses of fortresses protecting the naval ports. Additionally, we’ve ordered heightened vigilance for troops stationed near naval ports.”

“Well done. Now issue an imperial order throughout the Central Plains to conscript soldiers! I understand we can conscript up to 10 million. Has there been any change?”

At Emperor Xuande’s question, the Cabinet Secretary stepped forward to answer.

“No, Your Majesty.”

Thanks to Emperor Xuande’s repeated major purges, Ming’s administrative system had become very robust. The previously rampant fraud in military and household registers had disappeared.

According to these accurately recorded household registers, Ming’s population had already exceeded 100 million, and they could conscript up to 10 million troops.