The successful activation of the Geothermal Bore had transformed the barony's strategic math. For the first time, Kael had more energy than he had uses for it. The excess high-pressure steam hissed through the safety valves, a constant reminder of the volcanic power now at his disposal. While Arch-Magister Vane's forces waited for a cold-induced surrender, Kael decided to turn his energy surplus into a psychological weapon. He initiated the Sleepless Siege—a campaign of acoustic harassment designed to erode the Imperial resolve through the earth itself.
The technical execution relied on the Resonant Pipes. Kael knew that the underground iron network, originally built for communication, could be driven as a massive, subterranean organ. By connecting the high-pressure geothermal steam to a series of specialized vibration-valves at the base of the pipe-lines, he could create a constant, low-frequency infrasound—a hum that was below the threshold of hearing but well within the range of physical discomfort.
"We aren't trying to deafen them, Elms," Kael explained, adjusting a sliding iron sleeve on the primary resonator. "We want to target the resonant frequency of the human inner ear and the skeletal structure. It's a 'Ghost Frequency.' They won't hear it as a sound; they'll feel it as a persistent, unidentifiable anxiety—a vibration in their teeth and a tightness in their chests."
The grit of the operation was the modulation. A steady tone would eventually be tuned out by the human brain. To be effective, the sound had to be erratic. Kael designed a Randomized Cam-Wheel, driven by a small steam turbine, that constantly shifted the frequency and rhythm of the steam-pulses. The earth around Outpost Alpha began to "thrum" in a way that defied the natural patterns of the wind or the mine.
Socially, the Sleepless Siege required the citizens to adapt to a new sensory environment. While the vaults were heavily dampened by sand and wool, the low-frequency vibration still bled through the limestone. The "Mirror-Readers" in the command vault monitored the Imperial camp signatures on the Seismic Mirror. They watched for the "Jitter" of disorganized movement—soldiers pacing at night, the frequent relocation of tents, and the general breakdown of disciplined stillness.
The physical reality on the surface was grueling. The Imperial soldiers, already on edge from the Thermal Flare, now found that sleep was impossible. The ground beneath their bedrolls seemed to "twitch." It caused a specialized form of exhaustion known as vibration-sickness—headaches, nausea, and a profound sense of irritability. Vane's elite infantry, the backbone of the blockade, began to show the first signs of fractious behavior.
A technical failure occurred in the central resonator housing. The intensity of the high-pressure steam combined with the rapid vibration caused the iron mounting bolts to "walk" out of their sockets. The primary pipe shifted six inches, threatening to snap the lead-sealed joints and flood the lower engineering tier with live steam.
Kael and Drax responded with the "Tension-Jig." They couldn't stop the machine without ending the harassment, so they had to repair it while it was "live." They used heavy-duty iron chains and turnbuckles to re-anchor the pipe to the bedrock, their hands vibrating so violently they could barely hold their wrenches. The noise in the chamber was a physical assault, a high-pitched scream of escaping steam and the low-frequency roar of the resonator.
The Seismic Mirror showed a significant shift in the Imperial layout. Vane had been forced to move his primary command center even further back, nearly half a mile from the outcrop, to seek "Silent Ground." The blockade was thinning, the soldiers spreading out to escape the hum.
"They're tired, Elms," Kael said, his own eyes bloodshot from the constant vibration. "They've lost their focus. The hum is doing what the cold couldn't—it's breaking their discipline."
Kael looked at the population logs. The count remained 595. "But being 'safe' in a mountain isn't enough. We've turned ourselves into a ghost in the earth. To become an empire, we need to stop hiding and start recruiting. We need to turn Vane's exhausted men into our first 'External Aspirants.'"
He began sketching a new protocol: the Subterranean Broadcast. He would use the pipes not just for noise, but for a message of sanctuary.