The survival equation had a variable I hadn't accounted for: The Protein Gap.
"Yaks," Captain Hareth said, pointing to the map where a dense, frozen jungle bordered the mountains. "Great woolly beasts. One of them can feed the garrison for a week. They migrate to the jungle edge to eat the moss on the trees."
"So go get them," I said, looking at the empty larder. "We have the men. We have the weapons."
Hareth shook his head grimly. "We cannot, My Lord. The Yaks only move during the 'White Wind'—the blizzards. They use the snow to hide from the Orcs."
"Explain," I ordered.
"When the sun is out, the Frost-Orcs patrol the ground. They are seven feet tall and can cleave a man in two. In the sky, the Banshees circle—wretched flying things that scream to alert the Orcs. If we go out in clear weather, we are slaughtered."
"So we hunt during the blizzard," I reasoned.
"Impossible," Hareth sighed. "The wind carries ice shards. It freezes your eyelashes shut. If you open your eyes, you go snow-blind in minutes from the white glare. A man cannot hunt what he cannot see."
I tapped the table.
The Problem: The enemy has air and ground superiority during high-visibility conditions (Clear Weather). The Opportunity: The enemy is grounded during low-visibility conditions (Blizzards). The Constraint: Human optical sensors (eyes) fail in blizzards due to ice impact and UV glare.
The Solution: We don't need stronger swords. We need PPE (Personal Protective Equipment).
"Sand," I said suddenly. "Does the riverbed have white sand?"
"Aye, My Lord. It's mostly quartz grit."
"Gather it," I ordered. "And bring me seaweed or wood ash. We are going to fire up the furnace again."
The heat in the smithy was blistering. The new "Hypocaust" furnace was doing double duty—heating the dungeon below and melting silica above.
Tessa stood by the bellows, her magnetic field pulsing to drive the iron pumps faster than any human could.
"It is melting," the Blacksmith shouted, peering into the crucible. The sand had turned into a glowing, orange liquid.
"Pour it," I commanded.
The smith tipped the crucible. The molten glass poured onto a flat iron table I had prepared. I didn't need optical perfection; I needed transparency.
As the glass cooled into jagged, semi-clear sheets, Tessa looked at it curiously. She reached out her hand, trying to pull it with her magnetism. Nothing happened.
"It... it ignores me," she frowned.
"Glass is diamagnetic," I explained. "It doesn't care about your field. But I need you for the next part. I need frames."
I drew a diagram in the soot.
"Goggles," I explained. "Not just a flat plate. I need cups that fit tight against the eye socket, lined with leather/wool to seal out the wind."
Tessa nodded. She grabbed a handful of iron scraps. She didn't use a hammer. She closed her eyes, and the metal flowed. It twisted like clay, forming perfect loops to match the measurements I gave her.
"Now, the glass," Captain Hareth said, picking up a cooled piece. "We just glue this in?"
"No," I stopped him. "If you put a single piece of glass against a warm face in freezing wind, it will fog up instantly. You'll be blind in ten seconds."
I picked up two thin shards of glass.
"We use Double Glazing."
I placed one piece of glass in the iron frame. Then, I placed a thin ring of leather spacers. Then, I placed the second piece of glass.
"We trap a layer of dead air between the two lenses," I explained, sealing the edge with pine resin. "The outer glass stays cold. The inner glass stays warm. The air gap stops the energy transfer. No condensation. No fog."
I handed the finished prototype to Hareth. They were crude, heavy, and looked like something a steampunk welder would wear—but the lenses were double-sealed.
"Put them on," I ordered. "And go outside."
The blizzard was howling against the keep walls. It was a "Whiteout"—visibility was zero, and the wind carried stinging ice crystals.
Captain Hareth stood in the courtyard, the snow swirling around him. He strapped the heavy iron goggles over his head. The leather seals pressed tight against his face.
He looked up.
Usually, he would have squinted, shielding his eyes from the stinging ice. Usually, the glare of the snow would have forced him to look down.
But behind the double-paned glass, his eyes were wide open. The ice bounced harmlessly off the outer lens. The inner lens remained crystal clear, kept warm by his body heat.
He looked left. He looked right. He could see the gate. He could see the treeline.
He drew his sword, laughing. It was a manic, incredulous sound.
"I can see!" Hareth shouted over the wind. "My Lord! I can look right into the wind!"
I watched from the doorway, satisfied.
"The Orcs are hiding in their caves because they hate the cold," I told the shivering knights gathered behind me. "The Banshees are grounded because the wind would snap their wings."
I pointed to the jungle.
"The battlefield is ours. The enemy is blind, but we are not."
I tossed a bundle of the new goggles to the squad leaders.
"Go get me my yaks. We have a dungeon to stock."
Status Update:
Engineering Unlocked: Double-Paned Glass (Insulation), Snow Goggles (PPE).
Strategic Advantage: All-Weather Capability. The human army can now operate in conditions where the "superior" monsters cannot.
Resource Secured: Access to the Jungle (Yak Meat/Wool) via Blizzard Tactics.