"You are making... door hinges?" the camp smith asked, wiping sweat from his blackened forehead. He looked at the heavy iron bracket Ragnar was cooling in a bucket of water.
"In a way," Ragnar said, watching the steam hiss and rise. "I'm making a hinge that opens the gates of York."
Bjorn sat on an anvil nearby, sharpening his axe for the hundredth time. He picked up one of Ragnar's creations the release pin for the trebuchet's sling.
"It looks like a hook for catching a very stupid fish," Bjorn grunted.
"It's a trigger," Ragnar corrected, taking the metal back and inspecting it. It was crude, hammered out by hand, but the geometry was correct. "This little piece of iron decides exactly when the rock flies. Too early, the rock goes straight up and lands on our heads. Too late, and it smashes into the ground in front of us. Physics is unforgiving, brother."
Bjorn looked at the sky. "I prefer enemies I can hit. Physics sounds like it cheats."
"That's the point," Ragnar grinned, tossing the cold iron into a sack. "If you're fighting fair, you've already lost."
He slung the heavy sack over his shoulder. The fleet was prepping to sail. The tide was coming in. It was time for one last pitch to the CEO of this violent enterprise.
King Horik was in a good mood. This was terrifying for everyone involved.
The King stood on the beach, watching his warriors load barrels of salted meat onto the royal flagship. He was laughing as two men dropped a barrel and scrambled to pick it up.
"Ulf's son!" The King shouted as he saw Ragnar approaching. "The man with the fat ships! Have they sunk yet?"
"They float like ducks, my King," Ragnar said, bowing his head slightly. "And they are hungry for cargo."
"Good!" The King slapped his thigh. "Then load them. Why are you here bothering me with a sack of scrap metal?"
Ragnar took a breath. This was the hard part. Vikings respected strength. They respected courage. They did not typically respect standing three hundred meters away and doing math.
"I have a proposal, King Horik," Ragnar said. "A weapon to take York."
The King raised an eyebrow. "I have five thousand weapons," he said, gesturing to his army. "They are called Vikings."
"Vikings bleed," Ragnar said calmly. "Walls do not. York was built by Romans. Stone walls, three men thick. Ladders will cost us hundreds of lives."
Ragnar knelt in the sand. He didn't have the full machine that would require chopping down half a forest, which he planned to do in England but he had built a small-scale model out of firewood and twine to demonstrate the principle.
He set the little wooden frame on a flat rock.
The King's Huscarls gathered around, snickering.
"Is that a toy for your little brother?" one guard asked.
"It is a Siege Engine," Ragnar said, ignoring him. He placed a small pebble in the tiny leather sling. He loaded the counterweight bucket with a handful of lead fishing weights he'd borrowed (stolen) from his father's tackle box.
"Watch the driftwood log over there," Ragnar pointed to a piece of wood about ten paces away.
The King looked bored. "Get on with it."
Ragnar pulled the pin.
The heavy box dropped. The arm swung up with surprising violence. The sling whipped around the tip of the arm, accelerating the pebble faster than the eye could track.
The pebble slammed into the driftwood log with such force that it splintered the wood and sent chips flying.
The snickering stopped.
The guard who had mocked him took a step back. Ten paces was a long way to throw a rock that hard with a machine the size of a dog.
Ragnar stood up. "Scale that up," he said, looking the King in the eye. "Make the arm fifty feet long. Make the counterweight ten tons of rock. It doesn't throw pebbles. It throws boulders the size of cows. It crushes stone walls like they are eggshells."
King Horik looked at the splintered driftwood. He looked at the little toy machine. Then he looked at Ragnar with a mixture of impressed shock and deep distaste.
"It throws from far away?" the King asked.
"Outside the range of their arrows," Ragnar nodded. "We sit, we drink ale, we knock down their walls, and then we walk in."
The King scowled. He kicked the sand.
"It is... a coward's weapon," Horik grumbled. "Where is the glory in throwing rocks from the bushes? Where is the clash of steel? The poets will not sing of a machine, Ragnar. They sing of men."
"The poets can sing whatever they want," Ragnar countered, his voice steady. "But dead men don't hear songs. And dead men don't rule England. Do you want to be the King who died bravely at the foot of a wall, or the King who conquered York without losing his best men?"
The King was silent. He was a traditionalist. He wanted the fight. But he was also a conqueror. He wanted the prize.
"It is efficient," a voice said.
Ragnar turned. Princess Gyda had stepped forward from behind the King. She was wearing a cloak of white fur, and her eyes were locked on the little wooden model.
"Father," she said, her voice cool and melodic. "If we lose five hundred men taking the walls, that is five hundred fewer men to hold the city once we take it. The Saxons have more men than us. We cannot trade lives one-for-one."
She looked up at Ragnar. For a second, the rest of the world vanished. Her eyes were an intense, piercing blue, and they were shining with something that made Ragnar's engineer heart skip a beat.
"The counterweight," Gyda said, pointing a slender finger at the box of lead weights. "It uses the falling weight to create the speed? A lever?"
"A lever with a high ratio," Ragnar explained, feeling a smile tug at his lips. Finally, someone who spoke his language. "The short end is heavy, the long end is fast. It multiplies the force."
"A force multiplier," Gyda whispered, tasting the words. She looked at Ragnar, a small, impressed smile playing on her lips. "You have a dangerous mind, ship-builder."
The King looked between his daughter and Ragnar. He grunted, breaking the moment.
"My daughter has a point," Horik admitted, though he looked like he had swallowed a lemon. "I do not like it. It lacks... honor. But I like winning."
He pointed a calloused finger at Ragnar's chest.
"Pack your iron hooks. Pack your physics. When we get to England, you will build this 'Wall-Breaker.' But listen to me well."
The King leaned in, his voice dropping to a dangerous growl.
"If we stand outside the walls for weeks building your toy while the English laugh at us... if it does not work... I will put you in the sling and throw you at the wall. Do we have an understanding?"
Ragnar swallowed dryly. "Crystal clear, my King."
"Good," Horik barked. "Now get those fat ships in the water! The tide waits for no man, not even an engineer!"
An hour later, the Sea-Wolf was moving.
The sensation of the ship leaving the harbor was magical. The hull groaned as it took the weight of the open ocean, but the iron-reinforced keel held steady.
Ragnar stood at the stern, watching the coast of Norway slowly shrink into a grey line.
Bjorn was beside him, looking back at the hundreds of ships trailing behind them. It was an armada of wood and canvas, a swarm of locusts heading for the green fields of England.
"The Princess likes you," Bjorn said, breaking the silence.
Ragnar laughed, checking the rudder. "She likes the machine, Bjorn. She's smart. She sees the math."
"She looked at you like you were a piece of meat," Bjorn insisted, nodding wisely. "Smart meat. But meat."
"We're all meat in this era," Ragnar muttered. "I'm just trying to keep us from becoming dead meat."
He looked down at the sack of iron parts at his feet. The Trebuchet was a 12th-century invention. He was bringing it to the 9th century. He was skipping three hundred years of military development!
"Hey, Bjorn?"
"Yeah?"
"In England... there are trees called Yew trees."
"So?"
"So," Ragnar smiled, looking at the horizon. "After we knock down the walls, I'm going to make you a new bow. A longbow. We're going to change the world, brother."
Bjorn laughed, the sound carrying over the waves. "I don't care about changing the world, Ragnar. I just want to see that wall fall down."
Ragnar turned his face to the wind. The cold spray hit his cheeks.
"To England," Ragnar whispered.
"To Gold!" Bjorn shouted.
The Sea-Wolf surged forward, leading the way into history.