The change began not as an event, but as a thickening of the world itself. A strange, oppressive stillness settled over the frontier camp in the days following the bargain with Clerk Zhao.
The winds that usually scoured the plains died away, and a suffocating heat descended, pressing down like a physical weight. The sun, once a familiar presence, became a merciless brass eye in a bleached-white sky, baking the mud of the compound into a cracked, mosaic floor and raising a haze from the earth that shimmered with false promise.
The air grew thick and difficult to breathe, heavy with a stench that evolved from the usual background odor of men and animals into something far more sinister. The latrine pits, overfull and stewing in the heat, exhaled a visible, putrid miasma that hung in the motionless air, a foul blanket that coated the back of the throat.
Flies, once a nuisance, materialized in their thousands, a buzzing, black plague that rose in shimmering clouds from the waste trenches and descended upon the cook-pots and the sweating faces of the men with a relentless, droning hunger.
Lin Wei felt it first not in his lungs, but in the cool, silent space behind his eyes. His system, ever-vigilant, painted the environment in a palette of clinical alarm.
"[Environmental Alert: Ambient temperature 38°C. Humidity 85%. Pathogen incubation matrix: Optimal.]"
"[Risk Assessment: Fecal-oral transmission probability: 98.7%. Dysentery/Typhoid outbreak: Imminent.]"
He watched with a growing sense of horror that was entirely his own. He saw soldiers from the regular battalions, their discipline eroded by the heat, scooping water directly from the muddy river downstream from where the entire camp's filth was deposited.
He saw the flies crawling from the latrines to the open-air kitchens. He was watching a perfect, terrible machine of disease being assembled before his eyes, and he was the only one who could see the gears turning.
The first sign of the machine's output came a few days later. Lin Wei was returning from a now-routine visit to Clerk Zhao—a transaction that involved a pot of soothing ointment in exchange for a roll of clean linen—when he saw a soldier from the 4th Battalion suddenly stagger and vomit a thin, watery stream into the dust. The man clutched his stomach, his face a mask of cramping agony, before stumbling away towards the main camp's medical tents.
A cold knot tightened in Lin Wei's gut. It had begun.
He increased his pace, returning to the penal battalion's sector. The next morning, the rumors started, carried on the foul air. "The sweating sickness," men whispered. "A flux of the bowels. They say a dozen men in the 3rd Battalion are burning up with fever."
The response from the camp's medical authority was swift, and to Lin Wei's mind, catastrophically misguided. He heard the news from a nervous Sly Liu, who had ears everywhere. "Physician Wang has declared it an imbalance of the damp-heat humor," Liu reported, scrunching his nose. "Says the miasma from the marshes has poisoned the air. His apprentices are running around with pouches of some stinking herbs to burn."
Physician Wang. Lin Wei turned the name over in his mind. Not the same Wang from the magistrate's compound—a different man entirely, but cut from the same traditional, arrogant cloth. This Wang was the chief physician of the frontier army, a man whose reputation was built on ancient texts, not observable cause and effect. To him, illness was a philosophical concept, not a biological invasion.
Sharp and acidic frustration rose in Lin Wei. They were fighting an enemy they couldn't see with theories that were useless. He had to act.
He immediately transformed the penal battalion's corner of the camp into a fortress of hygiene. He became a tyrant of public health.
He designated two men whose sole duty was to keep a fire roaring under massive pots of water, their faces gleaming with sweat and determination as they boiled every drop that would be drunk.
He ordered a detail to the periphery to dig new, deep latrine pits far from the living quarters, their shovels biting into the hard earth to create a necessary remove from the filth. He distributed the strong soap acquired from Zhao and instituted a mandatory handwashing ritual, standing over the men like a stern priest as they scrubbed their hands raw before handling food or eating.
The penal soldiers, who had seen his strange methods save lives on the battlefield, grumbled but obeyed. They trusted the Doc.
To the outside world, however, the 7th Battalion began to look like a cult of madmen, obsessively boiling water and washing their hands while the real army dealt with the crisis.
Within a week, the main camp was a vision of hell. The sounds of drilling and marching were gone, replaced by a relentless, low-grade symphony of misery: the ragged coughs, the violent retching, the weak cries for water that only poisoned them further. The death toll began to rise, a silent, grim tally that hung over the camp heavier than the heat.
Seeing the scale of the disaster, Lin Wei made a decision. He composed a concise message, outlining the absolute necessity of boiling all drinking water and implementing strict camp-wide sanitation. He gave it to Scholar Zhang, whose literate hand and calm demeanor might lend it credibility, to deliver to Commander Xin's adjutant.
The answer came back not from the commander, but through the camp's bitter grapevine. Physician Wang had intercepted the advice. His response was scathing and public. He denounced Lin Wei's ideas as "the superstitious ravings of a criminal quack," a dangerous corruption of proper medical practice that would only anger the spirits causing the imbalance. He assured the command that his own treatments, based on centuries of scholarship, would soon restore harmony.
Standing at the edge of his battalion's meticulously maintained area, Lin Wei looked out at the dying camp. The stench of disease was now overwhelming. He could see figures lying listlessly in the shade, their lives seeping away into the filthy ground. The arrogance of ignorance was claiming more lives than any Jin sword.
He turned to his men, their faces grim but healthy. The contrast was staggering.
"The storm is here," he said, his voice quiet but cutting through the buzzing flies. "But it will not breach our walls. Their physician trusts in ancient words. We will trust in clean water. This ends when the rain comes, or the camp is empty."
The 7th Penal Battalion stood as a silent, orderly island in a raging sea of filth and death, its commander a heretic who understood a truth no one else could see.