The victory at the sluice gates had confirmed a hard truth: Ashfall was now a prisoner of its own geography. The intake weir—the vital throat of the aqueduct—sat three hundred yards outside the primary walls, shrouded by the river mists and the jagged shadows of the gorge. In the pre-dawn hours, the Duke's sappers could swim the current or crawl through the silt to place charges against the intake valves without a single sentry on the ramparts seeing them. Kael's math dictated that he could not station guards at the weir; they would be picked off by snipers or overwhelmed in the dark. He needed a sentry that didn't sleep, didn't breathe, and didn't rely on light.
Kael turned to the "grit" of early electro-chemistry. Utilizing the sulfur-acid byproducts from his new munitions research and the surplus of zinc-coated iron and copper scrap from the Iron Works, he began the construction of the Galvanic Line. This was the birth of the first primitive electrical circuit in the Protectorate—a low-voltage perimeter alarm designed to span the distance from the riverbed back to the central guardroom.
The technical foundation was the Galvanic Cell. Kael constructed a series of ceramic jars filled with a diluted acid solution, alternating plates of copper and zinc. While the current was weak, it was constant. He ran a thin, insulated wire—hand-coated in layers of hot pitch and silk—from the battery bank, along the base of the aqueduct, and looped it around the intake weir's primary support pillars.
"It's not a weapon, Rylen," Kael explained, his hands stained with the blue residue of copper sulfate. "It's a tether. If a sapper cuts the wire to clear a path, or if the movement of the weir-gates breaks the connection, the circuit is interrupted. At the other end, a magnetized needle will drop, triggering a mechanical bell."
The "grit" of the project was the insulation. The frontier winter was a conductor's nightmare. The wire had to be buried in a shallow stone conduit to protect it from the frost and the scavenging animals that would bite through the pitch. The Tier 0 laborers, led by Drax, were tasked with the "Silent Trench"—digging the three-hundred-yard line in the dead of night to avoid detection from the Duke's eastern scouts. They worked in freezing mud, their fingers numbing as they laid the delicate, pitch-soaked thread.
A technical failure occurred during the first calibration. The resistance of the three-hundred-yard copper wire was higher than Kael's initial calculations had accounted for. The weak galvanic current dissipated before it could move the heavy iron needle in the guardroom. The bell remained silent, even when the wire was intentionally severed.
Kael had to engineer the first Signal Relay. He realized he couldn't push the current the whole way; he had to "amplify" the signal's impact. He designed a sensitive balanced-armature—a tiny iron lever held in place by a weak magnetic field. Even the smallest fluctuation in current would cause the lever to tip, releasing a heavy lead weight that provided the kinetic energy to ring the alarm bell. It was a mechanical amplifier for a chemical signal.
Socially, the "Galvanic Project" was viewed with deep suspicion. To the Aspirants, the idea of an invisible "force" traveling through a wire was bordering on the occult. Rumors spread that Kael was capturing the lightning of the summer storms and storing it in jars. Kael countered this by bringing the "Information Citizens"—the telegraphers—into the workshop. He showed them how to maintain the acid levels in the jars and how to test the circuit using a small "Galvanic Spark." He was turning the "magic" into a measurable, maintainable industrial task.
The first true test came on the fifth night. The alarm bell in the guardroom didn't just ring; it slammed against its iron housing with a frantic, metallic urgency. The circuit at the intake weir had been broken.
Kael didn't wait for a visual confirmation. He signaled the Gray Fang to ignite the Magnesium Flare. This was a new tool—a high-intensity pyrotechnic charge made from powdered limestone and the magnesium-rich slag found in the deep mines. The flare erupted over the river gorge, bathing the intake in a blinding, unnatural white light.
The light revealed four sappers from the sulfur plant, frozen in mid-motion. They were waist-deep in the river, holding heavy iron crowbars and a leather-wrapped charge of the Duke's new black powder. They were staring at the glowing wire they had just snapped, their faces filled with a primal terror of the "invisible sentry."
Rylen's nozzle crews didn't need orders. The high-pressure water monitors, already calibrated to the intake's coordinates, opened fire. The columns of water struck the gorge with the force of falling masonry, sweeping the sappers into the rapids and dousing their fuses before they could be lit.
Kael stood in the guardroom, looking at the tripped lead weight of the relay. The "Galvanic Line" had worked. He had successfully turned the barony into an entity with an electronic nervous system. But as he reset the needle, he noticed a rhythmic "pulse" in the current—a steady, deliberate fluctuation that didn't match the flow of the acid.
"They aren't just cutting the wire anymore, Elms," Kael said, his eyes narrowing as he watched the needle vibrate. "Someone on the other end is trying to 'mimic' the current. They have an engineer of their own now. Someone who understands the jars."