After arriving in Xuzhou and initially organizing over twelve hundred troops, ensuring that the four surname great clans and Tanzhou forces that had infiltrated Xuzhou didn’t dare act rashly, the most urgent matters Han Qian needed to accomplish first were: building the Wuliu Creek weir, constructing dwellings, cultivating fields, and settling the Feng family slaves and refugees stranded within Xuzhou territory.
Only this way could they obtain a more solid foundation for establishing themselves in Xuzhou. Otherwise, with merely twelve hundred troops, how could he restrain Tanzhou from the upper Yuan River given such complex power dynamics within Xuzhou territory?
Never mind restraining Tanzhou from the upper Yuan River—he didn’t even have the capability to deal with the over a thousand elite troops Tanzhou had infiltrated into Xuzhou and assembled in a stockade at the foot of Zhongfang Mountain, let alone the four surname great clans watching them like venomous snakes from the deep mountain forests on both banks of the Yuan River.
And the indigenous tribal peoples outside Xuzhou were equally hostile toward them!
Standing before the walls of Longya City, he could even see the vigilant and hateful gazes of scouts from Jiming Stockade hidden in the shrubs. A few days ago, two of his men had carelessly pursued a wounded elk they’d shot and inadvertently ran to the Old Dragon Head area, where they were killed and wounded by tribal soldiers there—one dead, one injured.
Han Qian had to temporarily endure all this for now. He currently lacked the capital to confront the surrounding indigenous major surnames.
Without a basic-scale group supporting his father and son, unable to obtain basic material supplies from the locality, twelve hundred troops with unstable morale were truly insufficient!
And if these twelve hundred men under their control suffered significant casualties in combat with other forces, they had nowhere to obtain replacements.
Only after settling and winning over the Feng family slaves and some refugees stranded in Xuzhou territory, further gathering the migrant Han people who had previously moved to Xuzhou but had considerable conflicts with indigenous tribal peoples, and resolving the destabilizing factors among their current troops, would Han Qian and his father finally gain an initial foothold in Xuzhou.
However, even if they won over all the Feng family slaves, refugees, and migrant Han people, men and women, old and young combined would only total sixty to seventy thousand people—equivalent to just one moderately-sized county in the Jiangdong region.
With only this population base, on one hand arranging twenty to thirty thousand people in such a short time, on the other hand still needing to eliminate Tanzhou forces that had infiltrated their territory by next autumn and winter, pacify the four surname great clans, and ensure the capability to restrain Tanzhou from the upper Yuan River while properly handling hostility from surrounding indigenous surnames—where was the shortcut?
Han Qian placed his greatest hopes on his improvements to contemporary iron smelting and steel forging methods.
Previously, he had spent four full months at Yandang Jetty pondering iron smelting and steel casting methods, building a forge house and various experimental blast furnaces and hand forges. On the foundation of wind bags, he created bellows, gathering Chen Jitang and others for continuous experimentation with new methods.
He had even sacrificed the tight transport capacity of the Xuzhou fleet to ship iron ore, pig iron, and coal stone from Xuzhou for various experiments, all to adapt to the iron ore, pig iron, and coal stone produced in Xuzhou.
This was mainly because iron ore and coal stone from different regions had vastly different compositions. Han Qian needed to develop a set of iron smelting methods based on the iron ore, pig iron, and coal stone produced in Xuzhou—even specifically from Longya Mountain.
Otherwise, how could Du Yijun directly assume the position of master craftsman at Longya City’s iron smelting facility without mastering true iron smelting theoretical foundations?
This was because the processes employed at Longya City’s iron smelting facility had been repeatedly explored and refined at the Yandang Jetty forge house. Besides Chen Jitang and Du Yijun, the Han family had six other craftsmen and over a dozen manor slaves who had continuously participated in this work for four months—all of whom had now come to Xuzhou.
The iron smelting facility Ji Xiyao built in Longya Mountain, whether the blast furnaces constructed or the processes employed, all used new methods Han Qian had refined at Yandang Jetty.
Currently, only the smoldering of coal stone to remove impurities following the charcoal production method had been experimentally undertaken after arriving in Xuzhou.
Although Xuzhou’s forest resources were abundant and even using all charcoal for iron smelting could be sustained in the short term, the problem was that currently using this method to water-wash and smolder coal stone to remove impurities could still save enormous amounts of manpower compared to producing charcoal.
And what Han Qian most lacked at present was manpower. Almost no one believed he could accomplish anything with the meager personnel at his disposal!
Otherwise, how could Tanzhou have easily let him pass through Dongting Lake?
Of course, after Du Yijun switched to using smoldered coal stone for iron smelting, two new changes appeared in the previously established iron smelting process—but these two were positive changes…
“After we replaced charcoal with smoldered coal stone, furnace temperature increased noticeably. The time to melt the same amount of iron can be shortened by ten to twenty percent. Additionally, the supporting strength of residual smoldered coal stone is much greater than charcoal…” Du Yijun reported the new changes he’d observed during this period to Han Qian.
“Is that so? This is excellent news! Take me to see!” Han Qian strode briskly toward the iron smelting facility behind Longya City with Du Yijun and others.
Increased furnace temperature wasn’t simply a matter of shortening pig iron production time by ten to twenty percent.
Through four months of experimental exploration, Han Qian had already determined that iron’s melting point was directly related to carbon content—the lower the carbon content, the higher the melting point.
This was also why contemporary methods could only obtain wrought iron with nearly zero carbon content through continuous forging that might last months or even years.
Removing impurities from iron material and reducing carbon content to extremely low levels was called “refined through hundred forgings, flexible enough to wind around fingers,” hence called wrought iron—actually what later generations called soft iron, also known as old iron.
Because wrought iron’s carbon content was extremely low and melting point extremely high, contemporary blast furnaces couldn’t melt wrought iron, so there was no way to directly obtain true soft iron through furnace smelting.
Therefore, increasing furnace temperature was forever the key to improving and advancing iron smelting and steel casting methods.
Now using smoldered coal stone to replace charcoal could increase furnace temperature somewhat. They could even directly pour out molten iron for stirring. While the molten iron hadn’t yet cooled, this would expose carbon impurities to air for further combustion and direct removal, while other impurities could also form slag that precipitated below the molten iron through combustion, thereby directly reducing carbon and impurity content. How much effort would this save for subsequent forging?
Han Qian had already tested this method with small vertical blast furnaces at Yandang Jetty.
However, Yandang Jetty couldn’t build large-scale bellows facilities. With fuel mainly being charcoal, unable to stack very high, furnace temperature couldn’t increase to the degree Han Qian anticipated. The cooling speed of poured molten iron was also too fast, so results weren’t very ideal. But it proved worth investing effort to explore.
The vertical blast furnaces built here in Longya Mountain were twice as tall as the experimental furnaces at Yandang Jetty, allowing construction of larger water-powered or animal-powered bellows and accumulation of more fuel. Now smoldered coal stone could further increase furnace temperature, providing Han Qian even broader imaginative possibilities.
Han Qian thought to himself: what if molten iron from vertical blast furnaces was poured into new crucible furnaces for stirring to remove carbon and impurities under high temperatures, then poured out to cool?
This in fact combined contemporary iron smelting and frying steel processes—in later generations called the dual furnace method. Compared to cooling molten iron into pig iron blocks then heating and melting again for decarburization and impurity removal, this saved much more fuel and was far more efficient!
Han Qian didn’t expect to directly obtain truly refined soft iron, but if this method could obtain refined iron with appropriate carbon content, how much effort would that save compared to contemporary frying steel methods?
The significantly improved supporting strength of residual coal was also a phenomenon worth loudly celebrating.
The vertical furnace iron smelting built here in Longya Mountain had molten iron outlets and slag outlets at the bottom, with charcoal inlets and material inlets at the top. After ignition, charcoal material supported the iron ore for reactions. The resulting molten iron flowed through gaps to the bottom for extraction. But iron smelting had to stop before the charcoal material could no longer provide support, preventing column collapse.
How much iron a vertical furnace could smelt in one batch and how much iron ore could be added was directly related to residual charcoal’s supporting strength.
Currently, one vertical blast furnace in Longya Mountain could produce seven hundred jin of iron per batch. If the supporting strength of residual smoldered coal significantly improved, one batch could increase to a thousand jin—how much more could efficiency improve?
With this foundation, it would also facilitate future construction of vertical blast furnaces with larger furnace chamber volumes that could produce two thousand or even four thousand jin per batch!
These experiences were all explored by Han Qian over the past four months at Yandang Jetty. When he fled Jinling, he “destroyed” the various experimental furnaces, so naturally he also had to bring out all Han family craftsmen who had mastered these experiences.
Han Qian rushed to the iron smelting facility where sentries stood guard.
The iron smelting facility was built between a gentle slope and Longya City’s southwest stockade wall. Though it only had three vertical blast furnaces over one zhang tall plus some smaller forging furnaces, it occupied over a hundred mu. The charcoal kilns were also built within the iron smelting facility, so sufficient area had to be ensured for coal and ore stockpiling yards.
After Han Qian confirmed that Du Yijun hadn’t exaggerated the effectiveness of smoldered coal stone, he directly ordered one blast furnace shut down to build a crucible furnace at the molten iron outlet capable of high-temperature stirring or frying, testing the dual furnace steel smelting method he’d long pondered…
If this method succeeded, although manufacturing high-performance steel components needed for scorpion ballista limbs would still be very difficult, the lamellar armor, scale armor, refined iron blades, war spears, and other military equipment produced in Longya Mountain could have costs substantially reduced to one-third the level of other contemporary iron foundries.
Costs couldn’t be further reduced mainly because the iron smelting facility he built here wasn’t ideally located, with iron production limited by iron ore and coal stone mining and transport.
If the dual furnace method worked, Han Qian’s next step would be allocating several hundred more able-bodied laborers to increase workers at the coal yard and iron mine!
Imagine replacing ordinary iron arrowheads with refined iron arrowheads and refined steel arrowheads—how much would penetrating power increase?
Even agricultural tools like spades, shovels, hoes, and plows specially forged for the Wuliu Creek construction site to excavate canals and cultivate grain fields would improve efficiency by a large margin over ordinary iron implements.
Over the following half month, Xuzhou seemed to face the calm before a storm. The four surname great clans, Tanzhou troops, and migrant major households were all observing how Jinling would rule on the fate of the Han father and son, resulting in no actions whatsoever.
Han Qian remained in Longya City, personally overseeing the dual furnace modifications.
The crucible furnace for stirring or frying molten iron had a simpler structure than vertical blast furnaces, with much lower volume and height. It just needed to be positioned at the vertical furnace’s molten iron outlet—this could be solved by digging sloped pits and building furnaces on a stable foundation.
Therefore, the modification process for the first experimental dual furnace was still simple.
Fifteen days later, the molten iron from the first dual furnace batch was poured into elongated molds to cool. Watching the cooled iron blocks gleam with bright luster—if this wasn’t refined iron, refined steel, what was it?
Sword and blade forging involved performance requirements for blade edges versus spines and was quite complex to truly process. But armor plates and scale pieces needed for lamellar and scale armor only required simple forging of thin iron.
Comparing these with armor pieces made by traditional frying steel forging methods revealed that armor pieces cast by the new method had nearly identical performance.
A suit of lamellar armor consisted of hundreds of armor pieces laced together. Scale armor had even more pieces. Traditional armor-making technology heated and fried small pig iron blocks then repeatedly forged them into shape.
One armor-making master craftsman typically needed a full year to produce one superior suit of lamellar armor.
If armor pieces weren’t fried and forged but thin iron sheets were directly used as armor pieces, to obtain equivalent protective power, iron lamellar armor would need to be over twice as heavy.
Armored soldiers wearing such iron armor might exhaust their stamina after a single charge.
Protective power, armor weight, and armor-making efficiency were forever three irreconcilable contradictions in contemporary military equipment craftsmanship.
Refined iron smelted by the new method also required a certain degree of cold forging under water-powered forging hammers before armor piece quality could further improve. But compared to traditional lamellar and scale armor craftsmanship, efficiency was vastly higher, and requirements for armor-making master craftsmen could also be substantially reduced.
After Han Qian confirmed refined iron smelted by the new method could be used to make lamellar armor, he immediately conscripted over a hundred youths aged fourteen to sixteen from among the Feng family slaves and soldiers’ children as apprentices to supplement the military equipment workshop.
Left Bureau scouts were elites among elites. During the defense of Xichuan, they had also captured much. Including returning convict soldiers, Xi clan members, and boatmen’s guild armed guards—as long as they had achieved military merit and obtained martial honors, or needed to be incorporated into the State Battalion for service, they were all allowed to directly carry captured weapons and armor back home.
Therefore, the twelve hundred troops Han Qian assembled in Xuzhou had generally complete weapons and armor without much shortage. Generally speaking, Longya Mountain was the least in need of urgently expanding military equipment workshops.
However, among Xuzhou troops, what soldiers wore was still mainly leather armor.
Besides six to seven hundred suits of leather armor, the army also had over a hundred heavier iron armor suits, but only twenty-some suits of refined steel lamellar armor.
Battle commanders like Tian Cheng with strong martial skills and sufficient strength could wear leather armor inside with refined steel lamellar armor outside. As long as they didn’t encounter bed crossbows firing volleys point-blank, they dared charge even facing longbow arrow formations.
Leather armor or slightly lighter iron plate armor could still resist ordinary iron arrowheads at some distance. But what if the opponent’s longbows were now fitted with sharper, more penetrating refined steel arrowheads?
Material improvements corresponded not merely to productivity increases, but also to increases in killing capability and efficiency!