The firmament screamed. The sky above Pyrrhan was filled with crimson anger. Squadrons of Blood Angels Stormbirds streaked over the battlefield in the direction of the great forge. There were so many engines howling at maximum velocity that Hierax could hear them over the grinding rumble of the tanks. The glare of the exhausts was a purging light, brighter than the baleful, flickering glow of the fortress. The gunships were the Warhawk IV model, winged giants, each carrying a hundred Legiones Astartes. If the tanks of the XIII and I Legions were a battering ram into the mass of the daemons, the IX Legion was a hurling spear into the foe’s heart.

Hierax watched the flight of Angels until his internal sentinel signalled the coming of yet another movement. He faced forwards again, and opened fire with the storm bolter.

The Warhawk Talon of Baal flew over a land begging for flame. Sanguinius stood at the open side-door. He held on to the bulkhead and leaned out into the wind, looking towards the great forge and the pillar linking it to the gate. The speed of the Talon blurred the enemy below, turning the daemons into a grasping abstraction. Bursts of psychic fire lashed upwards at the Stormbirds. It was scattered. The daemons’ attention was still concentrated on the ground attack. The manufactorum reared ahead. It had appeared at first like a broad-shouldered mountain, a volcano of warp-altered industry. The Blood Angels flew between lesser forges, large as mountain chains. They held traces of the human constructs they had once been, now distorted by immensity. Chimneys were thousands of feet high. Conduits were half a mile thick. Vaulted archways had turned into fanged maws, iron and flesh and stone indistinguishable.

The primary manufactorum dwarfed them all. As it filled Sanguinius’ sight, he could see here, too, the echo of the thing it had been.

At his side, Raldoron asked, ‘How will we know what to attack inside?’

‘Look,’ said Sanguinius. ‘You can see the essence of what was taken by the enemy. The principles of the construction have some of the human in them.’ The manufactorum was built of monoliths the size of hive cities, but it was still recognisable. It was still a foundry.

‘They use us,’ said Raldoron. ‘Everything about us.’

‘Yes. Do you see what that means? At some level, they need us as the foundations.’ Or our horror is simply the worse for seeing the human endeavour made monstrous, he thought. ‘What we know, we can fight,’ he said. ‘What we can fight, we can destroy.’

They know us well enough to fracture us along every weakness. Time we turned that principle against them.