The heat didn’t decline gradually. It fell off a sky cliff.
At two in the morning, the spirit heat gauge mounted outside Giles’s transit shack read ten degrees above zero.
By two forty-five, the dark red liquid had plummeted to twenty-five degrees below zero. It pooled at the very bottom of the graduated glass tube.
In the forest beyond the cleared buffer zone, the rapid heat contraction struck the ancient hemlocks and black spruces.
Loud gunshot cracks echoed through the darkness as frozen tree trunks split from crown to root, their moisture expanding into solid ice.
A dense curtain of white powder drove level across the valley, whipped by fifty-mile-an-hour gale winds.
The air pressure soared, pushing chimney smoke down in heavy, swirling gray curls against the frozen mud lanes.
Yet inside the residential cabins of Rustgate Outpost, the air was sixty-four degrees Fahrenheit.
Giles Croft walked down the central lane between the bunkhouses, his wool coat buttoned to his chin and his surveying level slung across his chest.
Caleb walked beside him, carrying a tub of heated sheep fat mixed with beeswax.
At each cabin, Giles inspected the chinking between the squared spruce wall logs.
The double layer of dried sphagnum moss and compacted river clay had hardened into an airtight baked-clay seal.
Above their heads, the roofs bore three feet of packed snow resting atop eighteen inches of dried peat sod.
“The R-value of trapped air within compacted snow and dried peat is extraordinary,” Giles noted. He pressed his gloved hand against a timber joint.
“Snow has a heat flow rate of zero point zero five watts per meter degrees of star-heat.
By leaving the snow pack undisturbed upon the turf roofs instead of sweeping it off, we have gained twelve inches of natural heat padding.
The inside living quarters need only a quarter-cord of birch per day to maintain sixty-four degrees.”
Caleb dipped his wooden paddle into the animal fat bucket, sealing a hairline fissure around an oak door frame where frost was beginning to feather.
“My grandfather used to say the Great Winter of forty-two froze thirty men in their beds in High Timber,” Caleb muttered, smoothing the animal fat flat.
“They burned their furniture, then their floorboards, and died freezing in their blankets.
Here... The children are sleeping in their linen shirts without coughing.
The heat rises through the floorboards like summer sunshine.”
“Grandfathers in feudal villages built stuffy cabins with green wood and direct ground-contact sills,” Giles replied in his usual matter-of-fact tone.
“Tiny blood vessel moisture draw from frozen subsoil robs eighty percent of indoor heat through heat flow.
Our raised stone footings and under-floor air-flow chimney pipes create an isolated heat envelope.
The chimney pipe gases from the communal hearth circulate beneath the sleeping platforms before venting through the central stone chimney.
Basic building code rule-following saves lives.”
Giles and Caleb stopped at the burning lime powder dry-hopper storage sheds behind the north castle wall.
Giles ran his glove over the heavy canvas hoods lashed over the hopper hatches.
“Check the tarpaulins, Caleb,” Giles instructed.
“If blowing snow penetrates the seams and contacts the burning lime powder, the hydration reaction initiates prematurely inside the bins.
Four tons of boiling calcium hydroxide inside a wooden shed will burn the storehouse to the ground before the wolves even reach our ditch.”
Caleb pulled the lashing ropes taut, hammering an extra oak wedge into the hatch battens.
“Airtight and bone dry, Lord Giles,” Caleb assured him.
“Not a flake of snow gets inside. The lime is powdery as wheat flour.”
Giles turned toward the north gate ramp.
“Now we ensure our combat personnel don’t freeze upon the narrow high walkways.”
* * *
Up on the northern wooden wall, the conditions were brutal.
The wind howled through the timber embrasures, throwing blinding swirls of diamond dust against the breastworks.
Any bare skin exposed to the gale would freeze solid in under sixty seconds.
Yet Captain Kenneth Drake was running his watch rotations with clockwork care.
Every twenty minutes, a whistle blew from the gatehouse tower.
Half the archers on the narrow high walkway stepped down the ladder into the heated shelter of the lower blockhouse. Meanwhile, a fresh squad, warmed by the hearths and coated in sheep-animal fat frost-salve, took their places along the firing line.
Inside the lower blockhouse, Millicent and Sister Teresa inspected every returning soldier.
“Hands out, palms up,” Millicent ordered, checking fingers for the telltale waxy white pallor of early frostbite.
“Rub them with sheep fat and warm vinegar.
Nobody puts their hands near the open flames.
Rapid reheating causes tissue blistering and cellular black rot.
Warm them slowly in your armpits.”
Outside on the narrow high walkway, Kenneth stood at the north corner angle, his woolen face-veil frosted white around his nostrils.
Beside him, Kroll adjusted his heavy boiled-leather brigandine.
“In the northern crags, we lost half a company on the castle walls to a freezing blow like this,” Kroll said. He spat tobacco onto the boards.
“Our captain didn’t believe in windbreaks. Men froze solid standing up.”
Kenneth gestured to the forty-five-degree hemlock hurdles mounted atop the breastworks.
“Lord Giles angled these timber baffles to deflect the polar gale upward,” Kenneth said.
“Creates a dead-air pocket behind the wall. The wind screams over our helmets instead of cutting our throats.”
Douglas walked past, tapping the double-planked hemlock breastworks with his hammer.
“Two layers of three-inch hemlock planks, packed with six inches of tamped river clay between them,” Douglas said with pride.
“A charging beast could hit this wall at full gallop and only rattle the spikes.
No arrow or claw punches through that composite sandwich.”
Borin and Douglas stood by the heavy swivel giant crossbow. It was covered in grease-cloth tarpaulins to keep ice from jamming the release pawls.
Borin tapped a light crust of frost off the trigger latch with a small brass drift pin.
“Animal fat on the pivot pin,” Borin grunted.
“Smooth as a maiden’s cheek. She’ll trip the instant Drake pulls the cord.”
“How are the men holding, Captain?” Giles asked, stepping up onto the firing deck.
“No frostbite,” Kenneth reported, banging his gauntlets together to dislodge rime.
“The animal fat salve keeps the skin from cracking, and the twenty-minute relief rotation keeps their blood moving.
Every bowstring is waxed with beeswax and bear grease to stop moisture freezing on the hemp fibers.
If a bowstring takes on ice, the speed drops twenty percent and the string snaps on release.”
Giles nodded in satisfaction.
He checked the liquid silver probe set into the oak breastwork.
“External surrounding is negative twenty-six point four degrees.
At this heat, iron weapons stick to bare skin on contact.
Ensure no man touches bare steel without wool liners.”
Giles turned his field glasses toward the northern outer edge.
Out past the cleared four-hundred-yard buffer zone. There, the timber skidway sloped down into the valley floor, the swirling curtain of snow suddenly parted for a brief moment.
Through the whiteout, twin points of pale, glowing sapphire ignited in the darkness.
Then another pair.
Then twenty.
Then a sprawling sea of glowing cold blue eyes, stretching across the entire width of the northern ridge.
The beasts were massive, four feet at the shoulder, their fur matted with icicles and blue rime that cast an unearthly glow upon the snowdrifts.
They moved not with wild, uneven animal bounding, but in tight, organized tactical wedges.
As they breathed, clouds of crystal-clear cyan mist spilled from their jaws, hissing as it contacted the snow.
The blue frost-mist rolled down the slope ahead of them like an avalanche of frozen vapor.
Toby Karr gripped the low roof wall railing, his knuckles white.
“The blue mist... It turns the pine needles to glass,” Toby whispered, shivering despite his thick wool coat.
“Look at the branches snapping under their own weight.”
“Ice-cold moisture precipitation,” Giles explained in his flat, analytical flat voice.
“Their exhalations contain supercooled water droplets soaked with elemental frost mana.
Upon contact with sky nuclei, it freezes instantly, releasing latent heat of fusion into the surrounding air.
It looks menacing, Toby, but it possesses zero moving penetration against seasoned timber.”
Giles picked up his pacing board, checking the snow stakes set in the ditch.
“Notice the counterscarp grade,” Giles added, pointing with his pencil.
“Our digging crews cleared the loose powder from the forty-five-degree slope.
When their front paws strike the exposed, frozen clay, the static friction multiplier drops below zero point one.
Powder snow would have provided braking pushback. Clean frozen clay provides none.”
At their center, pacing slowly through the drift, loomed a monstrous shape nearly seven feet tall at the withers, its skull crowned with jagged crystal-clear horns of azure ice.
“The Frost Alpha,” Kenneth murmured, his hand dropping to the handle of his broadsword.
“Leading from the center rear. Just like a cavalry general.”
Giles adjusted the brass focus ring on his field glasses, studying the lead beasts. They stepped onto the cleared sled skidway.
“Look at their gait,” Giles said.
“The weight spreading is packed on their front claws.
On powder snow, their surface area prevents sinking.
However, when they hit our packed, forty-five-degree clay counterscarp, their ground contact pressure will exceed eighty pounds of pressure.
They can’t stop their forward heavy rush.”
Down along the wooden wall, not a single defender cried out or broke ranks.
The eighty men and women of Rustgate stood shoulder to shoulder behind the heavy squared spruce breastworks.
Their arrows were notched. Their giant crossbow winches were locked on hardened steel pawls, their hearts beating steady with heat energy.
Behind them in the courtyard, Sister Teresa and her slurry crew stood ready by the burning lime powder water chute valves, steam pluming from the pre-heated water tanks.
The great pack reached the edge of the cleared buffer hall, pausing at three hundred yards.
The massive Alpha lifted its crystal-clear head. He opened jaws lined with three rows of semi-clear ice fangs.
An ear-splitting, unearthly bellow ripped across the frozen valley, shattering the silence of the blizzard.
As one, five hundred frostblight wolves lowered their heads and charged down the greased skidway directly toward Sector Three.
Giles Croft pulled his graphite pencil from his coat pocket, marking the zero map point on his field board.
“Target vanguard has entered the engagement hall,” Giles said calmly.
“Archery squads, hold fire until they clear the four-hundred-foot marker.
Let the ground shape do its work.”