The diversion of the River Ash was not merely an industrial triumph; it was a geopolitical provocation. Downstream, the Duke's sulfur processing plant—already starved of peat fuel—now found its cooling channels reduced to a stagnant trickle of brackish sludge. Kael's models predicted a violent response within seventy-two hours. He knew the Duke could not afford to let the aqueduct stand. To protect the new lifeline, Kael had to transition the barony's plumbing from a utility into a weapon.
The "grit" of this transformation lay in the conversion of the aqueduct's terminal reservoir into a high-pressure head-tank. By utilizing the vertical drop from the Gray Fang ridge and the constant input from the hydraulic ram, Kael created a massive accumulation of potential energy. He directed the Iron Works to pivot from axle production to the forging of High-Velocity Nozzles—heavy iron cones with precision-ground apertures designed to focus the water's kinetic energy into a concentrated, lethal stream.
Kael supervised the installation of these nozzles along the northern and eastern ramparts. They were connected to the main reservoir via a secondary network of reinforced iron pipes, governed by massive "Sluice Valves" that required three men to turn. This was the Hydro-Static Defense System.
"It's not just water, Rylen," Kael explained as they calibrated the swivel mounts. "At this pressure, the stream can strip the bark off a tree at fifty paces. It will shatter a wooden shield and collapse a man's lungs through his gambeson. We aren't fighting with steel; we're fighting with mass and velocity."
The retaliation arrived on the third morning. A disciplined force of the Duke's men-at-arms, supported by the remaining penal-conscripts, advanced along the dry riverbed. They brought with them specialized "Fire-Sleds"—low-profile wagons loaded with the first stable batches of the Duke's sulfur-based incendiaries. Their goal was simple: reach the base of the aqueduct's brick piers and detonate the chemical charges to bring the structure down.
The social atmosphere in Ashfall was one of grim anticipation. The "Information Citizens" on the Gray Fang signaled the enemy's progress with a rhythmic precision that kept the barony in a state of high-alert. The Tier 0 laborers, who had nearly drowned in the caissons to build the intake, stood at the sluice valves with a possessive ferocity. They weren't defending a lord; they were defending the water they had bled for.
As the Duke's forces entered the "Kill Zone"—a two-hundred-yard stretch of open silt directly beneath the ramparts—Kael gave the signal.
"Open the primary gates!"
The sound was not a bang, but a terrifying, high-pitched scream as the water was forced through the iron nozzles. Three massive columns of water erupted from the walls, punching through the air with the weight of a falling mountain. The first stream struck a Fire-Sled, flipping the two-ton wagon as if it were made of straw and scattering the sulfur charges into the mud.
The grit of the engagement was the physical reality of hydraulic force. The raiders, expecting arrows or bolts, were utterly unprepared for the sheer physical weight of the water. Men were swept off their feet, their armor becoming a heavy, drowning burden as they were washed into the drainage trenches Kael had strategically excavated. The sulfur charges, dampened and buried in the slush, became inert.
However, a technical failure occurred at the eastern bastion. The sudden, high-pressure surge caused a "Water Hammer" effect—a shockwave of kinetic energy that traveled back through the pipes when a valve was closed too quickly. The iron pipe leading to the eastern nozzle shattered under the stress, sending a geyser of water into the internal courtyard and dropping the pressure for the remaining defenders.
Kael didn't flee the courtyard. He utilized the Manual Bypass. He led a team of Aspirants into the flooded zone, using heavy leather gaskets and iron clamps to seal the rupture while the water was still spraying. The force was enough to bruise bone, but they managed to divert the flow into the secondary defensive moat.
The "Fire-Sled" team leader, a desperate mercenary captain, attempted one final rush on foot, carrying a lit sulfur pot toward the central pier. Rylen didn't waste a bolt. He signaled the nearest nozzle crew. The stream hit the captain squarely in the chest, the pressure instantly neutralizing the incendiary and throwing the man thirty feet backward into the silt.
The Duke's force broke. They fled back toward the Salt-Spurs, leaving behind their sleds and a dozen men trapped in the mud of the new moat. Kael ordered the sluice gates closed. The scream of the water subsided, replaced by the heavy, wet silence of the riverbed.
Kael inspected the shattered pipe in the courtyard. The defense had held, and the aqueduct was intact. But the "Water Hammer" failure had revealed a new mechanical limit. The system was too powerful for its own plumbing.
"The pressure is a beast we haven't tamed yet, Elms," Kael said, wiping the freezing spray from his eyes. "We saved the water, but we nearly broke the house to do it. We need Pressure-Relief Valves and surge tanks. And we need to prepare for the Duke's next move. He knows now that his chemistry can't reach us. He'll stop sending sleds and start sending 'Sappers' to cut the intake at the source."