The twelve tunnel diggers who led the vanguard of the Azure Firmament Sect marched with the heavy, steady beat of men trained to break stone.
They were veterans of the deep-pit quarries of Mount Tian-Zhu. It was hard, broad-shouldered men whose skins had been pickled gray by years of underground coal-smoke and potion-made acid fumes. Each man wore a brigandine jacket of overlapping steel scales riveted to boiled ox-hide, heavy at the shoulders and knees with fluted plates of beaten iron. Over their iron skullcaps they wore wire-mesh face guards, through which their dark, bloodshot eyes stared out at the ancient walls with cold indifference.
Four of them carried two-man air-powered drills: heavy bronze cylinders four feet long, tipped with fluted chisels of man-made diamond, connected by armored leather hoses to a mobile steam-air pump dragged behind them on iron skids.
Four more carried heavy high-pressure spreading jacks. Iron screw-rams capable of exerting forty tons of lateral thrust, used to pry open buckled stone doorways and force collapsed portcullises from their tracks.
The leftover four carried repeating potion-made fire-lances. Long-barreled brass weapons mounted on shoulder-hooks, their magazines filled with high-pressure phials of dragon-oil that ignited upon contact with the air.
