Corax and Vulkan led their forces back to regroup and to allow the warriors of their brother primarchs a measure of the glory in defeating Horus, dragging their wounded and dead with them. The victory had been won, but the cost had been steep indeed, with thousands of all three Legions lost to the betrayal of the Warmaster. Horus's forces were in retreat, but there would be no celebration of the slaughter, no joyous victory feasts or glorious days of remembrance, only another sad scroll added to a banner that would never again see the light of day.

Scorched tanks rumbled alongside the Astartes, their ammunition expended and their hulls battered by the impact of shot and shell.

Unanswered vox hails requested medical aid and supply, but the line of Astartes at the top of the north ridge was grimly silent as the exhausted warriors of the Raven Guard and Salamanders came to within a hundred metres of their allies.

A lone flare shot skyward from inside the black fortress where Horus had made his lair, exploding in a hellish red glow that lit the battlefield below like a madman's vision of the end of the world.

And the fire of betrayal roared from the barrels of a thousand guns.

FULGRIM LAUGHED AT the stunned look on Ferrus's face as the forces of his *allies' opened fire upon the Salamanders and Raven Guard. Hundreds died in the fury of the first moments, hundreds more in the seconds following, as volley after volley of bolter fire and missiles scythed through their unsuspecting ranks. Explosions flashed to life in their midst, vaporising warriors and tearing through tanks as the force of four Legions ripped the beating heart from the first wave of loyalists.

Ferrus Manus watched in mute horror as he saw a storm of fire engulf Corax, and a titanic explosion mushroom skyward from where Vulkan stood in astonished outrage at what was happening.

Even as terrifying carnage was being wreaked upon the loyalists below, the retreating forces of the Warmaster turned and brought their weapons to bear on the enemy warriors within their midst. Hundreds of World Eaters, Sons of Horus and the Death Guard fell upon the veteran companies of the Iron Hands, and though the warriors of the X Legion continued to fight gallantly, they were hopelessly outnumbered and would soon be hacked to pieces.

Ferrus Manus turned to face Fulgrim, and the Primarch of the Emperor's Children could see the despair etched into his brother's features, his silver eyes dull and lifeless. To have so great a victory snatched away in an instant must be the most sublime sensation. Fulgrim almost wished to switch places with his brother just to taste that feeling for himself.

*Only dismal defeat and death await you, Ferrus,' said Fulgrim. *Horus has commanded your death, but for the sake of our past friendship I shall plead your case to him if you throw down your arms. You have to surrender, Ferrus. There is no escape.'

Ferrus Manus tore his eyes from the slaughter of the loyalist forces, his teeth bared with the volcanic fury of his home world.

*Maybe not, traitor, but only dishonour holds any terror for me,' spat Ferrus. *The Emperor's loyal warriors will not surrender to you, not now, not ever. You will have to kill every last one of us!'

*So be it,' said Fulgrim, launching himself towards Ferrus Manus, swinging his mighty warhammer. The primarchs' weapons, forged in brotherhood, but wielded in vengeance, met in a blazing plume of energy, and the battlefield was illuminated for hundreds of metres by their ferocious energies.

The two primarchs traded blows with their monstrously powerful weapons, the strength to defeat armies and topple mountains unleashed as they fought like gods forced to end their dispute in the realm of mortals. Ferrus Manus wielded his flaming blade in fiery slashes, his every blow defeated by the ebony hafted hammer he had borne in countless campaigns.

Fulgrim swung his hammer in great, looping arcs, its heavy head powerful enough to crush the armour of a Titan to paste. Both warriors fought with the hatred only brothers divided can muster, their armour dented, torn and blackened by the fury of their conflict.

To fight an opponent of such magnificence was a privilege, and Fulgrim savoured every clash of hammer and sword, every fiery line cut across his flesh and every grunt of pain torn from his brother's mouth as Forgebreaker glanced his armour. They circled in the midst of cries of pain and roaring savage glee, the Morlocks of Ferrus Manus slain, but for a last few desperate heroes.

Ferrus cut the shoulder guard from Fulgrim's armour and spun inside his guard to deliver a lethal thrust towards his groin. Fulgrim stepped to meet the blow, batting aside the tip of the fiery sword with the haft of Forgebreaker, and hammering the warhammer's head towards Ferrus's skull.

The Primarch of the Iron Hands took the blow, dropping to one knee and lashing out with his blade as blood streamed from the terrible wound in his temple. The sword's fiery tip cut across Fulgrim's stomach, opening his armour and tearing through his flesh. The pain was indescribable, and Fulgrim fell back, dropping his hammer as his hands sought to stem the blood pouring from his body.

Both primarchs faced each other on their knees through a haze of pain and blood, and Fulgrim once again felt an ache of sadness well within him. The pain of his wounds, and the sight of his brother's broken skull coated in blood, tore a window into his mind. The sensation was like a powerful gust of fresh mountain air, clearing away the fog that had wrapped him in a suffocating embrace for so long that he no longer noticed it until it was gone.

*My brother,' he whispered, *my friend.'

*You have long since lost the right to call me friend,' snarled Ferrus, pushing himself to his feet and staggering towards Fulgrim with Fireblade raised to smite him.

Fulgrim cried out, and his hand leapt unbidden to his waist as the flaming blade carved a burning path towards his neck. Silver steel flashed as he drew the sword he had taken from the Laer temple and blocked the descending weapon. Ferrus's sword hissed and spat as it bit into the silver blade, the Primarch of the Iron Hands' strength forcing the blazing metal, centimetre by centimetre, towards Fulgrim's face.

*No!' cried Fulgrim. *This is not right!'

The amethyst stone at the hilt of Fulgrim's sword pulsed with an evil light, bathing Ferrus Manus's face in a leering purple glare. Energy streamed from the blade, and musky smoke billowed around them, deadening sounds and obscuring sight. Fulgrim felt a monstrous presence swell around him, its power and nameless essence more intoxicating and dreadful than anything he could ever have imagined.

Diabolical strength flooded his limbs and he pushed against the power of Ferrus Manus, feeling his brother's surprise at his resistance. With a cry of animal rage, he surged to his feet and hurled Ferrus Manus back, spinning and lashing out with his sword.

The silver edge bit deep into the breastplate of his brother's armour, and the Primarch of the Iron Hands cried out, falling to his knees once again as the blade's flaring energies parted his dark armour like a fingernail through cold grease. Hot blood sprayed from the wound and Fireblade slid from Ferrus's hand as he gasped in fierce agony.

Finish him! Kill him! the voice screamed, and to Fulgrim it seemed as though it echoed across time and space as well as within his skull. He staggered with the blunt force of its imperative, lurching as though his limbs were not his to control.

His normal grace and elan were forsaken as he falteringly raised the silver sword in preparation of delivering the deathblow to Ferrus Manus. Unknown energies coruscated along the notched blade and down the length of his arms into the meat and bone of his wounded body.

Fulgrim was wreathed in purple fire. Crackling arcs of lightning caressed him with a lover's tenderness, seeking out his open wounds and licking them with balefire as they sought entry to his flesh.

Fulgrim stood above Ferrus Manus, his chest heaving convulsively as his entire body shook with the violence of the power that sought to claim him.

He must die! Otherwise he will kill you!

Fulgrim looked down at his defeated opponent and saw his own reflection in the mirrors of Ferrus's eyes.

In an instant that stretched for an eternity, he saw what he had become and what monstrous betrayal he had allowed himself to be party to. He knew in that eternal moment that he had made a terrible mistake in drawing the sword from the Laer temple, and he fought to release the damnable blade that had brought him so low.

His grip was locked onto the weapon and even as he recognised how far he had fallen, he knew that he had come too far to stop, the realisation coupled with the knowledge that everything he had striven for had been a lie.

As though moving in slow motion, Fulgrim saw Ferrus Manus reaching for his fallen sword, his fingers closing around the wire-wound grip, the flames leaping once more to the blade at its creator's touch.

Kill him before he kills you! NOW!

Fulgrim's blade seemed to move with a life of its own, but it had no need of such impellents, for he swung the blade of his own volition.

The silver blade clove the air as it swept towards Ferrus Manus, and Fulgrim felt the ancient triumph of the presence that he now knew had dwelt within it all this time. He tried desperately to pull the blow, but his muscles were no longer his own to control.

Unnatural warp-forged steel met the iron flesh of a primarch, its aberrant edge cutting through Ferrus's skin, muscle and bone with a shrieking howl that echoed in realms beyond those knowable to mortals.

Blood and the monumental energies bound within the meat and gristle of one of the Emperor's sons erupted from the wound, and Fulgrim fell back as the searing powers blinded him, dropping the silver sword at his side. He heard a shrieking wail, as of a choir of banshees, whip around him as phantom, skeletal hands clawed at him, and a thousand voices tore at his mind.

Ghostly whirlwinds seized him and spun him around, twisting him like a limp rag in their grip, and threatening to tear him limb from limb in retribution. Even as he welcomed such oblivion, he felt another presence move to protect him, the same presence that had guided his sword arm, the same presence that had been his constant companion since Laeran, though he had not known it.

Fulgrim fell to the ground as the winds released him, and faded with a shrieking howl of anguished frustration. He landed heavily and rolled onto his side, heaving great gulps of cold air into his lungs as the sound of battle returned to him. He heard cries of pain, gunfire, explosions and the rhythmic crack of bolters as they fired relentless volley after volley. It was the sound of death.

It was the sound of a massacre.

His entire body aching with pain and loss, Fulgrim pushed himself upright. Blood and the detritus of battle surrounded him, the stoic figures of armoured warriors staring in wonder at the headless body that lay on the black ground before him.

Fulgrim took a shuddering breath and raised his hands to the heavens, screaming his loss at the sight of his brother so cruelly murdered.

*What have I done?' he howled. *Throne save me, what have I done?'

What needed to be done.

Fulgrim heard the voice as a sibilant whisper in his ear, the breath of the speaker hot on his neck. He twisted his neck, but there was nothing to be seen, no unseen speaker or mysterious presence.

*He's dead,' whispered Fulgrim, the aching loss and guilt of his crime too monstrous to believe. *I killed him.'

Yes, you did. With your own hands, you struck down your brother, he who had only thought well of you and fought faithfully with you through all the long years.

*He... he was my brother.'

He was, and all he ever did was honour you. The looming presence that surrounded him and spoke to him seemed to claw at his eyes with insubstantial fingers, and Fulgrim felt his mind wrenched into the realm of memory, seeing once again the battle against the Diasporex and the Fist of Iron coming to the rescue of the Firebird. He saw the resentment he had picked at for months, only now understanding the altruism of Ferrus Manus's deed and the loss of life his selfless act had incurred. Where before he had seen only self-aggrandisement in his brother's action, he now saw it for the heroic deed it had truly been.

His brother's critical comments, the wounding darts meant to undermine him, he now saw had been jests designed to puncture his self-importance and restore his humility. What he had perceived as Ferrus's prideful boasts and rash actions had been deeds of courage that he had spitefully dismissed.

Ferrus's rejection of his attempt to betray him was the act of a true friend, but only now did he see how his brother had, even then, tried to save him.

*No, no, no,' wept Fulgrim as the true horror of what he had done struck him with the force of a thunderbolt. He looked around through tear-filled eyes and saw the horrific changes wrought upon his beloved Legion, the perversions that masqueraded as epicurean pleasure.

*Everything I have done is ashes,' he whispered and swept up the golden Fireblade, so recently wielded by his brother in an attempt to undo the evil Fulgrim had embraced.

Fulgrim reversed the blade and held its fiery tip against his body, the edge blackening his hands and burning the skin through the rents torn in his armour.

To end things now would be the easiest thing in the world; to take away the guilt and wash the pain away in a sharp thrust of steel into his vitals. Fulgrim gripped the sword tightly, drawing blood from his palms where the blade's edge sliced his skin.

No, noble suicide is not for the likes of you, Fulgrim.

*Then what?' howled Fulgrim, hurling away the sword his brother had forged.

Oblivion: the sweet emptiness of eternal peace. I can grant you what you crave... an end to guilt and pain.

Fulgrim rose to his feet and stood tall beneath the storm wracked clouds of Isstvan V, his once beautiful face streaked with tears, and his pristine armour stained with the blood of his beloved brother.

Fulgrim lifted his hands and looked at the blood there.

*Oblivion,' he said, his voice hoarse. *Yes, I crave the boon of nothingness.'

Then leave yourself open to me and I will put an end to it all.

Fulgrim took a last look around. The grim-faced warriors who had foolishly thrown in their lot with the Warmaster: Marius, Julius and thousands more were damned, and they could not see it.

All around him, he could hear the sounds of the future, of warfare and death. The thought that he shared the guilt of the destruction of the Emperor's dream was the greatest shame and sorrow he had ever known.

An end to it all would be a blessed relief.

*Oblivion,' he whispered as he closed his eyes. *Do it. End me.'

The barriers in Fulgrim's mind dropped and he felt the elation of a creature older than time as it poured into the void in his soul. No sooner had its touch claimed his flesh for its own than he knew he had made the worst mistake of his life.

Fulgrim screamed as he fought to keep it out, but it was already too late.

His consciousness was crushed into the dark, unused corners of his mind, forever to be a mute witness to the havoc wrought by his body's new master.

One moment Fulgrim was a primarch, one of the Emperor's Children, the next he was a thing of Chaos.

TWENTY-FIVE.

Massacre Daemon The Last Phoenix LESSER TROOPS WOULD have given up and accepted their fate in the face of such overwhelming opposition, but the warriors of the Salamanders and Raven Guard were Astartes. So they fought like never before, knowing their doom was at hand, and desiring to make the traitors pay in blood for every one of their number that fell.

Caught between two armies, the first wave of the loyalist forces was being systematically massacred. Unrelenting gunfire from the Iron Warriors at the drop-site, and the resurgent forces along the Urgall Depression crushed the Salamanders and Raven Guard in a terrifying vice, and cut them to pieces in a murderous storm of fire and blood.

Warriors of the Alpha Legion and Word Bearers followed their leaders onto the black plains of Isstvan V, their guns blazing and their chainswords bright as they cast off the last remnants of their loyalty to the Emperor and turned their weapons on their brothers.

The Dies Irae killed scores with every shot of its mighty weaponry, striding like a giant daemon of legend through the benighted slaughter. White-hot fire blossomed amongst the loyalists and killing flames sawed across the black desert, vaporising men and turning sand to glass. Traitor tanks roared from the Urgall Hills, weapons blazing and crashing the wounded beneath their tracks. The Iron Hands were lost, the fate of their primarch a mystery as his last known position was overrun by hordes of screaming enemy warriors.

Let slip from his false retreat, Angron carved a bloody path through the loyalists, his swords reaping a bloody tally through the ranks of his enemies. The Red Angel fought in a barbaric frenzy, his mind lost to all but the killing rage that drove his blades. His warriors hacked and chopped their foes like butchers, in a killing frenzy of berserk rages, slathering their armour in the blood of the fallen.

If the noise of battle had been incredible before, it was deafening now, no voices heard that were not screams of pain or hate. Individual sounds were lost amid the constant roar of gunfire and rambling explosions, melding into one long immense howl of murder. What had begun as a battle had become a massacre, each pocket of loyalist resistance gunned down with overwhelming superiority of fire, before the shredded survivors were hacked apart with bloody chainswords.

Mortarion harvested loyalists with great sweeps of his scythe, his ragged cloak billowing in the hot winds of the battlefield's fires, as the Death Guard crushed their foes beneath the relentless pounding of marching feet and the disciplined volleys of gunfire.

At the forefront of the Emperor's Children, Lord Commander Eidolon and the swordsman Lucius led a contingent of their warriors into the heart of the enemy, killing with wondrous displays of bladework and howling shrieks of raw sonic power. The swordsman danced through the battle, his Terran blade carving a screaming, bloody path as he laughed in time with music only he could hear.

Marius Vairosean and his orchestra of damnation ploughed the bloody sand with their terrifying harmonics, ripping open flesh and metal with shrieking chords and howling scales. In contrast, Julius Kaesoron took little part in the fighting, expending his energies in the mutilation and defilement of the corpses left in his brother's wake. Trophies of flesh hung from his armour, each violation he wreaked on the flesh of the enemy more extreme than the last.

Apothecary Fabius picked his way through the carnage like a vulture, pausing here and there at fallen Astartes to perform some gruesome extraction. A coterie of warriors protected him and hideous homunculi assisted him in his loathsome labours, the fruits of which were borne behind them in a vile procession of bloodstained organ bearers.

Fulgrim was nowhere to be seen, the magnificent primarch lost amid the destruction of the Iron Hands' Morlocks, but even without him, his warriors fought with savage and exquisite glee.

With victory in his grasp, the Warmaster took to the field of battle, surrounded by Falkus Kibre and his Justaerin Terminators. The remnants of Horus's Mournival fought alongside him, the Warmaster's magnificent black armour and amber chest adornment gleaming bloody in the firelight.

The killing fields of Isstvan V ran red with the blood of the loyalists, their brave attempt to halt the rebellion of Horus little more than ragged flesh and blood that fought for the last shreds of honour left to them.

Here and there, fierce resistance overcame the traitorous forces and desperate bands of heroes fought their way clear of the trap, dragging their wounded with them towards the few surviving drop-ships.

A band of Raven Guard smashed through a cordon of Emperor's Children who shrieked in orgasmic pleasure as they were cut down, too immersed in the sensations of their own pain and death to fight back. A black-armoured captain led the breakout, fighting his way towards a miraculously undamaged Thunderhawk as his warriors bore the grievously wounded body of their primarch towards escape.

Of Vulkan there was no sign, his warriors cut off and surrounded by the Night Lords and Alpha Legion. Gales of bolter fire hammered the brave warriors of Nocturne and obliterated them. Not all the Salamanders were so cruelly slaughtered, others following the Raven Guard's example and battling their way to their aircraft and the hope of escape.

The few remaining Iron Hands, bereft of their primarch's leadership, banded together with the Salamanders and a brave few managed to break out of the hideous massacre, but such successes were the merest fraction of the battle.

Within hours the slaughter was complete and almost the entire strength of three complete Legions lay silent and dead on the tortured sands of Isstvan V.

THE ONCE-GREY skies of the planet burned orange with the reflected glow of a thousand pyres. The firelight bathed the rippling, glassy sands in a warm radiance, and towering pillars of black smoke from the burning corpses filled the air. Lucius watched the blizzard of ash fall like snow from the skies and stuck out his tongue to taste the greasy, ashen tang of the dead.

Beside him, Lord Commander Eidolon, the skin of his face stretched and waxen over his bones, watched the cremation of the dead with dull, glassy eyes.

*We need to be moving again soon,' said Eidolon. *We have no time to waste with pointless ritual.'

Privately, Lucius agreed, but he kept his counsel as the thousands of Astartes loyal to Horus filled the broken desert of the Urgall Depression. They gathered before a great reviewing stand, constructed by the dark priests of the Mechanicum with astonishing speed. As the sun began to sink beyond the horizon, the smooth black planes of the stand shone with a blood red glow.