Projectiles was not an art of warrior instinct. It was the predictable intersection of projectile mass, first speed, air drag, and gravity gaining speed.
At sunrise, Giles Croft stood inside the north gatehouse castle wall with a steel engraving burin and a polished sheet of brass.
The brass plate was fixed to the timber cheek of the springald carriage, right beside the bronze height screw. On the metal, Giles was carving clean, precise numbers into a curved arc: four degrees, eleven degrees, twenty-two degrees.
Captain Kenneth Drake watched the burin carve the metal. He held his ten-foot iron-shod pacing rod like a sceptre.
“A warrior aims with his eye, my lord,” Kenneth said. His voice carried the skepticism of thirty years of border warfare. “He feels the wind on his cheek, gauges the drop of his arrow, and releases on the breath. How can a brass plate tell a soldier where a bolt will land in the dark?”
“A warrior’s eye is compromised by fight-or-flight rush, pupil dilation, and combat fatigue,” Giles replied without stopping his engraving. “Under stress, human distance estimation error exceeds thirty-five percent. In a night engagement, gunners routinely shoot over the enemy’s heads because fear makes them pull upward.”
He blew brass shavings from the groove.
“Gravity doesn’t experience fight-or-flight rush. At two hundred and forty feet per second, an eight-pound ash bolt follows a curved flight path described by standard kinematics. If you set the height screw to eleven degrees, the bolt will strike Cairn Two at two hundred yards. It has no physical choice in the matter.”
Outside, along the southern roadbed, Toby Karr had finished whitewashing the three stone cairns.
Cairn One stood at one hundred yards. A cone-shaped pile of granite river boulders painted bright white with wet lime plaster, topped with a red pennant.
Cairn Two stood at two hundred yards, situated on a low gravel knoll.
Cairn Three stood at three hundred yards, near the edge of the dark pine forest where the ground rose toward the mountain defile.
Each cairn was a surveyed benchmark, measured to within two inches using Giles’s steel chain and sighting scope.
“Toby,” Giles called from the arrow embrasure. “Erect the three-hundred-yard target stake.”
Toby ran to Cairn Three. With a wooden mallet, the boy drove an eight-foot pine post into the peat. Nailed to the post was a circular wooden target shield, two feet in width, painted with a black bullseye.
Toby gave a double wave with his chalk-reel and sprinted sixty yards laterally into the scrub to clear the line of fire.
“Target sighted at Cairn Three,” Kenneth reported, stepping up to the height screw. “Range: three hundred yards. Setting height.”
Kenneth turned the threaded bronze hand-wheel beneath the breech.
The heavy oak transom groaned as the bronze screw lifted the rear of the carriage. Kenneth watched the brass pointer slide along Giles’s engraved arc until the needle lined up dead center with the mark labeled 22°.
“Twenty-two degrees locked,” Kenneth said.
“Crew, prepare to wind,” Giles commanded.
Four refugee recruits—young men from the burnt hamlets of Oakhaven who had spent the last three days drilling on the carriage—stepped into their positions.
Bran, a broad-shouldered blacksmith’s son, seized the left winding crank. Luc, a carpenter’s apprentice, took the right.
“Wind!” Kenneth barked.
CLACK-CLACK.
The bronze ratchets sang all at once. The four young men leaned their weight into the handles, their boots digging into the granite floor.
The two layered ash-and-steel arms drew inward, twisting the massive skeins of wire and sinew.
“Full tension reached!” Bran shouted, sweat dripping from his chin. “Locking dog engaged!”
The third loader, a youth named Peter. He lifted a six-foot ash sabot bolt from the storage rack. He laid the heavy missile into the bronze guide trough, sliding the notched butt against the hemp bowstring.
The fourth recruit pulled the safety pin from the bronze drop-sear.
Giles clicked his brass pocket watch. “Cycle time: forty-two seconds. Four seconds slower than drill standard. Luc, your hand-off was sluggish. Smooth is fast.”
“Aye, my lord,” the boy panted, his chest heaving.
Giles turned to Kenneth. “Bending is zero. Wind speed is three knots crossways from the west. Offset half a turn on the lateral screw.”
Kenneth turned the level crossing screw half a turn, shifting the carriage three-eighths of an inch to the left.
He took the lanyard cord in his gloved fingers.
“Standing clear of the recoil stops,” Kenneth announced. “Loose!”
He yanked the cord.
THWIP-SNAP!
The springald kicked three inches backward on its bronze casters. The twin layered arms slapped forward into the horsehair buffers with a sharp, explosive crack.
Across three hundred yards of open valley, the heavy six-foot bolt vanished into the sky.
For an entire second, there was only the hum of the shaking twisting force wire in the stone chamber.
Then, at Cairn Three, three hundred yards distant, the wooden target shield exploded into matchsticks.
CRACK!
The heavy chisel head struck the two-foot bullseye dead center. The pine post was snapped in half as if hit by a lightning bolt, the upper half cartwheeling twenty feet into the pines.
From his hiding spot in the scrub, Toby Karr jumped into the air, waving both hands over his head.
“Center hit!” Toby’s distant voice echoed down the valley. “Dead on the pin! Snapped the post clean through!”
Kenneth Drake stood frozen, his hand still holding the lanyard cord.
He looked from the smoking embrasure down to the brass plate on the cheek. There, the number 22 was engraved in clean, shiny lines.
“Three hundred paces,” Kenneth whispered, his voice trembling with respectful dread. “Without taking an eye-sight. We turned a screw to a number on a plate, pulled a cord, and split a pine post at the edge of the forest.”
“That’s what happens when you account for the gaining speed of gravity,” Giles said. He closed his pocket watch. “A 32.2 feet per second squared downward vector acts uniformly on all high-speed bodies. The brass plate is merely a graphical solution to a second-order polynomial.”
Kenneth shook his head, staring at the brass plate as if it were an ancient holy relic. “A grimoire of unerring death. If the Dun-Krag tunnel diggers had possessed five of these machines, the mountain citadel would never have fallen.”
“It’s not a grimoire, Kenneth. It’s a range table.”
For the next four hours, Giles drilled both battery crews relentlessly.
They fired at Cairn One at one hundred yards, setting the screw to four degrees. The bolt struck the white boulders, throwing sparks and pulverizing stone.
They fired at Cairn Two at two hundred yards, setting the screw to eleven degrees. The bolt pierced an iron-clad timber shield and buried itself in the gravel knoll.
By mid-afternoon, the crews were working in total silence, communicating through hand signals.
The reload cycle dropped from fifty seconds to forty-two, then to thirty-eight seconds flat. The young recruits no longer fumbled with the sabot cups or paused on the winding cranks. They operated like clockwork components inside an iron machine.
Sister Teresa climbed the castle wall stairs. She carried a basket of warm oatcakes and a pitcher of cold spring water from the aqueduct fountain.
“Eat, defenders of the stone,” Teresa said. She handed an oatcake to Bran, whose hands were black with animal fat. “The Master has numbered their graves upon the road. Every footstep they take toward this gate is already measured in the book of judgment.”
“Numbered cairns, Teresa,” Giles corrected, chewing an oatcake. “Not graves. If the raiders have rational officers, they will observe the markers, calculate our artillery envelope, and withdraw.”
“Bandits don’t have rational officers, Lord Giles,” Kenneth said quietly, cleaning the guide track with an oiled rag. “They have hungry men, stolen axes, and blood in their eyes. They will charge until the iron breaks them.”
Before Giles could reply, a shout rose from the outer raised stone road.
A horse came thundering across the barrel arch bridge, its hooves clattering wildly against the volcanic cement concrete.
The rider was Rook Red-Mane, the colony’s veteran scout. His red hair was plastered to his forehead with sweat, his wolf-skin mantle torn by thorn scrub. His lathered courser was blowing red froth from its nostrils.
Kenneth rushed to the low roof wall. “Rook! What news from the high pass?”
Rook vaulted out of the saddle before the horse had fully stopped, hitting the gravel in a hard crouch. He scrambled up the castle wall stairs. He took three steps at a time, his chest heaving like a blacksmith’s bellows.
“They have passed the Timber Gate,” Rook gasped, gripping the stone doorway. “Warlord Bronn is on the march. Five hundred men.”
Giles set his tin mug down on the carriage. “Detail the vanguard.”
“Three hundred dismounted cutthroats in boiled leather,” Rook reported, his breath coming in ragged bursts. “One hundred heavy crossbows behind tall body-shield shields. Fifty mounted outlaws on warhorses.”
He swallowed hard, pointing a trembling hand south.
“And the engines?” Kenneth asked, his face darkening.
“Three iron-headed battering rams, slung on cedar trunks,” Rook said. “And two huge siege towers, thirty-five feet high, rolling on eight-wheel timber ox-carts. They have armored mantlets on the fronts, boiling animal fat cooking pots on the top decks, and sixty archers in each tower.”
Rook looked at Kenneth, his gray eyes wide with veteran terror.
“They’re marching four miles a day, laying corduroy over the peat. They will be at our stone bridge in seventy-two hours.”
Kenneth Drake drew his trench-sword six inches, his knuckles turning dead white. He looked out through the arrow embrasure at the three white cairns gleaming in the afternoon sun.
“Seventy-two hours,” Kenneth whispered. “Five hundred axes and two siege towers.”
Giles pulled his brass slide rule from his vest pocket. He didn’t look at the south road. He looked at the blueprint pinned to the far wall.
“Two thirty-five-foot siege towers,” Giles muttered with clean, steady care. “Assuming four draft oxen per tower, their ground contact pressure exceeds forty pounds of pressure. An eighteen-ton chassis can’t cross a soaked high-pressure moat without immediate load-bearing subsidence.”
He turned to Caleb and Duncan, who had just arrived at the castle wall landing.
“Caleb, Duncan. Pack your tools. It’s time to dig the high-pressure moat.”