As the two Titans thundered forwards, the Vindicators churned over the breaches in the outer wall. The walls shook with thunderous impacts from the siege tanks, the inner gate pounded by shell after shell. The Dreadnoughts added their own weight of fire to the barrage. Three of the insane war machines, gripped in the frenzy of battle, lumbered forward to attack the gate with their massive hammer arms, only to be caught in the Vindicators' fire and blown apart.

The gap closed with every step of the Pater Mortis, and Honsou could clearly see the faces of the men lining the walls. Las-fire slashed towards him, but he laughed, feeling utterly invincible. He swayed forward as the Titan's arms pistoned into the walls, bracing hooks punching deep within the rockcrete.

Seconds later, the battle drawbridges slammed down from the shoulder bastions, crushing the rampart beneath them as they dropped.

Honsou raised his sword and charged onto the walls, shouting, 'This place is ours! Show no mercy!'

He jumped onto the rampart, hacking a trio of Guardsmen to death with one blow and firing his bolt pistol down the line of the walls. Hundreds of warriors were arrayed against them, but Honsou faced them all without fear, killing with preternatural skill.

Iron Warriors fanned out from the Titan's shoulder bastions, slaughtering the defenders and hurling them back. The noise was tremendous as the ramparts became slick with blood and entrails. Each time the Iron Warriors came close to breaking through the defenders' lines, the Imperial Fists would lead a desperate counterattack and push them back and hold the line together. Honsou killed another Guardsman and risked a glance to where Forrix led his warriors. Here too, the Iron Warriors were confronted with the incredible tenacity and stubborn defiance of the citadel's defenders.

They were holding, but only just, and Honsou saw they were close to breaking.

Honsou blocked a blow aimed at his neck and disembowelled his attacker as a monstrous, black shadow, darker than the blackest night fell across the walls. For the briefest second, the fighting slowed as heads craned upwards to see what new devilment had been unleashed.

With a thunder that cracked the walls, the Warsmith crashed down on the rampart, the newborn darkness of powerful wings spread behind him. Guardsmen around him dropped, vomiting blood and convulsing. His arms swept out, his taloned hand and mighty axe killing everything within reach. The darkness enfolding the Warsmith's head billowed and spat bolts of dark light that dissolved everything it struck.

Screams of terror spread along the walls and horrified soldiers turned and fled before this diabolical apparition. The Warsmith reared up to his full height, his armour stretching and swelling, the keening faces bound within his armour straining and wailing a banshee's choir.

Shaking off his amazement, Honsou bellowed, 'We have them now!'

He charged after the fleeing mass of soldiers, hacking them down with his sword. The Imperial front line collapsed and not even the Imperial Fists could halt the rout.

He could see Forrix slaughtering fleeing Guardsmen by the dozen. A terrific crash echoed from below, and Honsou knew the citadel's inner gate had fallen. The Warsmith took to the air once more as the carnage on the walls continued, casting his pall of corruption and change throughout the ramparts.

Honsou kicked down the iron door to one of the giant towers that flanked the gate and dived through, firing as he rolled. The soldiers within the tower screamed in terror as he rose to his feet. They were no threat, but he killed them anyway.

He swiftly made his way down the stairs, his blood afire and singing with the promise of victory.

'Iron Warriors! With me! The citadel is ours!'

Forrix thundered down the stairs of the tower, firing as he went. The stair spiralled downwards to the left, bolter shells whining and ricocheting from the walls. On two levels there were defensible landings, but the furious assault of the Iron Warriors could not be stopped. Forrix and his Terminators smashed each one aside with ease.

Even as he killed, he marvelled at the appearance of the Warsmith. Their leader stood at the very cusp of daemon-hood, the changes wracking his body becoming more manifest. Surely his final ascension was at hand? Forrix had sensed a terrible urgency to the Warsmith, and knew that he was fighting to hold his form coherent. One wrong move now and the Warsmith could just as easily explode into the thrashing riot of anatomies of a Chaos spawn, doomed for an eternal life of mindless mutation.

The base of the tower levelled into a wide killing zone, but it had been designed to defend against attacks from outside, not inside, and the defenders had nothing to shelter behind. Las-fire raked the walls beside Forrix. He swept his combi-bolter around the room, slaughtering Guardsmen with every pull of the trigger.

Terminators spilled down after him, their horned helmets carved in the masks of snarling beasts of prey. The image was not inappropriate, thought Forrix. Narrow doors led from the tower, too small to allow a Terminator through, but Forrix slammed his power fist into the stonework, shattering the lintel and punching his way through. The Terminators followed him outside into the citadel's interior.

Forrix grinned as he watched the Warsmith swooping high above the battlefield. The wings at his back were becoming more substantial and his form rippled and blurred, as though in a constant state of flux. Across the ruined gateway, he could see Honsou leading his warriors from the opposite tower, hacking down a mob of fleeing Guardsmen.

Ahead, across a wide cobbled esplanade, he could make out a cluster of ruined buildings, their windows gaping like blackened, empty eyesockets. Human soldiers, Vindicators, Dreadnoughts and Defilers poured through the blazing remains of the gate, gunning their engines as they spread out to avoid the return fire coming from the ruins.

Amidst the flames, sporadic volleys of las-fire pierced the night, but it was disorganised and undirected. Smoke billowed in thick, black plumes from the ruins and Forrix heard the crash of massive power claws tearing at the curtain wall behind him as the two Titans of the Legio Mortis ripped it down, eager to be part of the slaughter.

The smoke parted and the high-pitched blasts of Vulcan bolter fire ripped up the esplanade in a line towards the gate. Three Vindicators exploded and a Dreadnought toppled, thrashing its arms in frenzy as it tried to right itself.

Forrix charged across the courtyard as he caught sight of the Warhound he had marked for himself earlier. The beast darted through the smoke, pausing only long enough to draw a bead on the charging Iron Warriors. But in the open, its gunfire was nowhere near as effective as it had been in the breach.

'Spread out!' yelled Forrix as he gathered his Terminators to him and set off towards the Warhounds.

'You escaped me once, beast, but this time I have you,' he promised his prey.

'Mark your targets!' yelled Leonid as volleys of las-fire lashed the Iron Warriors charging from burning building to burning building. Smoke filled every street. None of their attackers were falling, and Leonid knew they must make every shot count. The Warhound Defensor Fidei walked backwards behind his men as they fell back from this assault, firing into the mass of the enemy as they pursued the Jourans.

Through gaps in the smoke pouring from shelled buildings, he could see massive chunks of rockcrete being torn from the wall by the Titan siege towers, and knew they had only minutes until these gargantuan war machines joined the battle. Tanks and grotesque, multi-limbed constructs, with turrets adorned with hateful runes, poured through the smashed gate, and fear was visible in every bloodied face.