At Sejong's command, Hyang and Choe Hae-san led Sejong and the ministers to a building set aside for them.
Inside the largest room, chairs were prepared, and Sejong and the ministers could sit comfortably.
Once all preparations were complete, Hyang began to explain the new armor in earnest.
"Upon examining the armor used by our Joseon army, we generally wear chainmail or lamellar armor. However, these armors require a lot of effort to make and maintain. Moreover, all soldiers, including those on duty and those serving in the military, must provide their own armor, leading to significant differences in quality."
Sejong and the ministers nodded in agreement with Hyang's explanation. They had often received petitions reporting the hardships of the people and demanding solutions to these issues.
"Among the soldiers, some wear paper armor or wooden armor due to financial constraints, but their defensive capabilities are inferior to iron armor."
"That's true."
Sejong nodded at Hyang's explanation. Hyang then pointed to the new armor with a baton and continued.
"Starting from the late Goryeo period, the new armor called dujeong-jeop has been used. It enhances defensive capabilities by attaching iron plates to the back of cotton armor. In terms of defense, it can block arrows from a distance of 50 paces. It is the strongest armor in terms of defense."
Sejong and the ministers nodded again. During the previous conquest of Daimado, the dujeong-jeop had indeed proven to be the strongest armor. Hyang continued.
"However, this dujeong-jeop has several problems."
Hyang pointed out the issues with the dujeong-jeop.
-First, it requires a lot of time and labor to produce. Each iron plate must be individually forged and attached to the dujeong.
-The cost is also a problem. While the iron and cotton are expensive, the silk lining and the fur for the sleeves, sides, and collar are even more costly. Although cotton or silk can be used, the best quality requires rabbit, deer, or fox fur.
-Despite being the strongest in defense, it has many weaknesses. The sleeves, sides, and collar are all exposed. While this is not a problem statistically unless one is extremely unlucky, it becomes an issue in close combat. To address this, additional guards for the armpits and groin are required, but the problem with the front remains.
-It is difficult to wear for long periods. This is because the armor is designed like a robe, and the entire weight is supported by the shoulders, leading to easy fatigue.
"To solve these problems, we have modified the new armor as follows."
-We replaced the iron plates inside the cotton armor with a single iron plate. We secured the protection of the upper body with two iron plates, one in the front and one in the back.
-We addressed the defense issues of the front and sides. The single iron plate solved the front problem, and we made the front and back plates overlap by half an inch to solve the side problem. We also attached round iron plates to the shoulder and arm guards to address the armpit problem.
-We divided the armor into two parts, called sang-jeop and jeop-han, to distribute the weight across the entire body, reducing fatigue even when worn for long periods.
-We added new iron plates to the shin, elbow, and knee areas to enhance protection.
"That's how we created this new armor."
Hyang pointed to the armor hanging on the last stand and concluded his explanation.
"Hmm~."
"Hmm…."
After Hyang's explanation, Sejong and the ministers carefully examined the problematic armor. Sejong, who was inspecting the armor, asked Hyang a question.
"Compared to the existing dujeong-jeop, how much heavier is this new armor?"
"It is 8 geun (about 4.8 kg) heavier. The additional weight comes from the new shin, elbow, and knee guards."
"Only that much heavier?"
Sejong looked doubtful, and Hyang immediately explained.
"First, the number of dujeong has significantly decreased, and instead of cotton armor covering the iron plates, we used cotton fabric."
Sejong stroked his beard and calculated.
"So, with these adjustments, the total weight increased by 10 geun.
"Who will wear this armor?"
"The cavalry and swordsmen will wear the full-body armor, and the modified upper armor will be used by the musketeers and artillerymen. The helmet will be used by all soldiers."
"What do those who have worn it say?"
"Although it is slightly heavier, the weight is distributed across the entire body, making it surprisingly bearable. Additionally, the increased coverage by the iron plates has made the soldiers feel more secure and less fearful."
Sejong stroked his beard again.
"That part can only be known through actual combat. I would like to see the structure of this armor in more detail."
"It is already prepared."
At Hyang's signal, soldiers brought in a large table. On the table were iron plates with the outer cotton fabric removed.
"Hmm… The shape of these iron plates is truly unique."
Sejong's eyes sparkled as he examined the breastplate and backplate, along with the other iron plates. Hyang smiled inwardly at Sejong's reaction.
'I was surprised too, even though I made it!'
When Hyang first saw the prototype of the new armor, he shook his head slightly.
'What is this? This terrible hybrid?'
The armor Hyang designed was a combination of Western full plate mail and dujeong-jeop.
While studying the problems with the armor, Hyang was at a crossroads. Full plate mail had a slight edge in defense, while dujeong-jeop was slightly better in mobility.
"Hmm. What should I do? Should I just let the armor part go?"
However, Hyang could not just let the armor part go. There was the issue of the swordsmen, who would be responsible for close combat.
"This is quite a dilemma…"
Ultimately, the decision to improve the armor was driven by the maintenance issues of chainmail and lamellar armor and the high production costs of dujeong-jeop. The cost to properly produce dujeong-jeop was 16 seok 10 du for the armor and 4 seok 5 du for the helmet.
"Why is it so expensive!"
Surprised by the higher-than-expected cost, Hyang investigated the reasons. He found that while the material costs were high, the labor costs were even more significant.
In the end, Hyang made a decision.
"Let's just change it! We need to reduce all material costs and minimize labor costs as much as possible!"
To achieve this, Hyang borrowed the design of full plate mail.
While Sejong was discussing his impressions of the new armor, Hwang Hee, who had been meticulously observing the armor, asked Hyang a question.
"Your Highness."
"Yes."
"From what I can see, the iron plates of the helmet and armor appear to be made from a single sheet of iron. Is that correct?"
"Yes."
"Then the craftsmen must have hammered and processed each plate individually, which is very labor-intensive and could lead to cost issues."
Hwang Hee's point made Hyang nod.
"A valid observation. I had the same concerns, so…."
Pausing for a moment, Hyang smiled at Hwang Hee and continued.
"We used a press to make them."
'The beginning of mass production is the press!'
This was the reason Hyang had to borrow the design of full plate mail.
* * *
Sejong asked Hyang with a critical expression.
"You said the new armor will be worn by cavalry and swordsmen. However, to my knowledge, there is no such military unit as swordsmen. Is this a new unit?"
"Yes. We have integrated the pangbaesu, changsu, and janggeomsu into one unit."
"Why?"
"Considering the performance of the new muskets and cannons, our Joseon army will operate primarily with muskets, cannons, and cavalry. Training separate units for pangbaesu, changsu, and janggeomsu would strain the budget. Therefore…."
"You decided to integrate these units. Is that correct?"
"Yes."
Sejong immediately pointed out the potential issues with Hyang's answer.
"At first glance, your reasoning seems sound. However, the situation on the battlefield can change in an instant, and relying solely on swordsmen could be problematic. If the firepower of the muskets and cannons is insufficient to suppress the enemy and they break through the swordsmen's defense, what will you do?"
Hyang nodded at Sejong's question.
"I am aware of that. To address this, we have increased the number of long muskets. These can also be used as spears, and we are teaching the musketeers spear techniques using the long muskets."
"Long muskets as spears? Hmm…."
Sejong, intrigued by Hyang's explanation, recalled the length of the long muskets he had seen at the demonstration.
'If you attach a spear blade to that? Hmm… Perhaps…'
After considering various possibilities, Sejong nodded.
"It seems feasible. However, I will delay adjusting the entire Joseon army's structure according to your suggestions. I believe it is not too late to make a decision after seeing the results in actual combat."
Hyang bowed in acceptance of Sejong's decision.
'I will follow Your Majesty's decision.'
* * *
After the demonstration of the new weapons created by Hyang, Choe Hae-san, Lee Cheon, and the officials and craftsmen of the research institute, Sejong and the ministers prepared for a thorough inspection of the accounts.
"However, I'm feeling a bit hungry."
Sejong, who had been watching the demonstrations since early morning, felt hungry and looked at the ministers.
"Shall we return to the palace for lunch?"
At Sejong's suggestion, Hyang interjected.
"Your Majesty, would you like to try the dried rations prepared for the soldiers?"
"Dried rations? Are they tasty?"
Sejong showed curiosity at Hyang's suggestion. However, Hyang shook his head slightly in response to Sejong's question about the taste.
"Dried rations are for soldiers to eat when they cannot cook meals on the battlefield. They are not known for their taste."
'They are not the famous French military rations!'
"Hmm… What should we do…."
Sejong stroked his beard, pondered for a moment, and then made a decision.
"Alright, let's try them. We need to understand the hardships of the soldiers. Ministers, let's all try them."
The ministers, who had to eat the food that even the crown prince did not confidently recommend, responded hesitantly.
"I will follow Your Majesty's command."
Shortly after, soldiers brought in a large pot of steaming porridge. Other soldiers followed with bowls of white kimchi and empty bowls. After clearing the armor parts from the table, the soldiers placed the pot and kimchi on it and took their seats.
"Your Majesty, please try it."
"Hmm? Alright, let's try it."
As Sejong stood in front of the table, a soldier politely bowed and used a ladle to scoop thick porridge into a bowl, which he then offered with both hands.
Sejong, seemingly enjoying the taste, finished the bowl of porridge. After handing the bowl to the server, Sejong continued to ask Hyang questions to identify any issues.
"Do the soldiers eat this amount for one meal?"
"Yes."
"Since it's porridge, how long can it sustain them?"
"At least until the next meal. It contains not only barley and rice but also a significant amount of meat."
While nodding at Hyang's explanation, Sejong continued to ask questions to identify potential problems.
"Making porridge requires a lot of water. However, one of the biggest challenges in war is securing a water source. What is your solution to this?"
"We have created a template to use when clean water is difficult to obtain."
"A template for purification? Let me see it."
"I will show you."
Hyang led Sejong to a spot outside the building. There, a wooden frame about the length of an adult's calf was stacked with square sieves, forming a structure about a foot (about 90 cm) tall.
"This is the purification template."
"How does it work?"
"Starting from the bottom, we layer charcoal, wood ash, and sand, each about three inches (about 10 cm) thick. On top, we place gravel about two inches (about 7 cm) thick."
After explaining, Hyang signaled the soldiers. The soldiers filled a large bucket with water and mud to create muddy water and poured it over the gravel.
After a moment, clear water trickled out from the iron pipe at the bottom of the lowest sieve. Hyang, who caught the water in a gourd, offered it to Sejong.
"The water is clear."
"While it filters out visible impurities, there may still be invisible impurities, so it should be boiled before consumption."
"Hmm… With this template, we can have a countermeasure even if the enemy uses scorched earth tactics."
The most common tactic encountered when suppressing the Jurchens beyond the border was scorched earth. The Jurchens would throw dead animals into wells or block them with stones to contaminate water sources. This made it difficult to suppress the Jurchens for extended periods.
Most military officers in the Joseon army's headquarters and training institute, who had experience fighting the Jurchens, had pointed out this issue, and Hyang had created a portable water purifier as a solution.
"Hmm…."
Sejong, who had been examining the purifier while listening to Hyang's explanation, turned to the ministers.
"When droughts or floods occur, the biggest challenge for the people is securing clean water. This template could solve that problem, don't you think? It is easy to make, does not require much material, and performs very well."
After a moment of thought, the ministers all bowed in agreement.
"Truly a wise decision, Your Majesty!"
"Given the frequent water shortages due to droughts and floods, this will be the best solution!"
No minister opposed.
During droughts, people would dig wells to find water. Even when water came up, it could not be consumed immediately because it was muddy. People had to endure thirst until the mud settled.
During floods, the same issue arose. Streams, rivers, and wells all turned into muddy water, and people suffered from thirst even when water was abundant. Drinking the muddy water out of desperation often led to illness, which could spread and cause epidemics.
With the ministers' approval, Sejong ordered Hyang.
"Prepare a document detailing the production of this template and distribute it to all government offices nationwide."
"I will follow Your Majesty's command!"
"Also, the dried rations seem suitable as emergency food. If confirmed to have a long shelf life, consider mass production."
"I will follow Your Majesty's command."
"These dried rations are surprisingly tasty. They would make a good snack in the palace when I'm hungry."
"Thank you, Your Majesty!"
'You found the dried rations, which are only supposed to be edible, tasty? Your Majesty! Do you have a military constitution?'