Here, William King recounts the Battle for the Emperor's Palace - a cataclysmic event that almost brought an end to the Imperium and forever altered the First Founding legions...

On the thirteenth of Secundus, the bombardment began. From orbit, the Warmaster's ships laid down an unrelenting barrage of missiles and deadly energy beams. The aim was to cripple the defences around the Emperor's Palace and make possible a massive invasion of Earth. The lunar bases had already fallen, and the defending Battlefleet Solar had been scattered. On Mars, as across the entire vast Imperium, bitter civil war raged.

On countless worlds, blood-mad warriors clashed. Those who had pledged loyalty to the Emperor fought those who had sworn fealty to Warmaster Horus and, through him, to the dark powers of Chaos. The Emperor's realm was in turmoil and some of the greatest battles in human history were being fought. On the hive-world of Thranx over a million warriors died in a single day on the killing fields of Perdagor. On the blazing deserts of Tallarn, at the Ka'an Salient, fifty thousand tanks clashed in the greatest armoured action of all time. During the space drop on Vanaheim, three hive-cities were depopulated by rebel forces as a warning against resistance, yet still the defenders fought to the last man.

Like a cancer, the Heresy infected the entire structure of the Imperium. Everywhere brave men gave up their lives to try to excise that cancer.

It was on Earth, at the very heart of the Emperor's realm, that the fate of the galaxy was to be decided. In those last days, the sky was black with dust clouds and the earth split by gigantic fissures. Tectonic plates shifted under the stress of the bombardment. Mountain chains shivered and seas evaporated and became barren deserts. Rains of blood and ash dripped from the dark sky. Astropathic choirs sang of evil portents and men went mad with fear. Hideously twisted ships full of the lost and the damned hung in orbit over the ravaged world. Shielded from the devastation by the cunningly wrought defences of the Adeptus Mechanicus, a pitiful few stood ready to repel the invaders.

The embattled remnants of the Emperor's army were desperately trying to hold out until reinforcements arrived. The Emperor himself oversaw the defence of his fortress-palace, personally commanding the Adeptus Custodes, his elite guard. He was accompanied by Sanguinius, white-pinioned Primarch of the Blood Angels and his legion of Space Marines. In the palace grounds stood the stalwart Adeptus Arbites. The palace was not the only bastion of resistance; there were others, each an awesome fortified city filled with dauntless soldiers. Beneath the ruins of the Imperial Basilica, grim visaged Rogal Dorn led the stern Imperial Fists in final prayers. Within the armoured factory complexes of the Adeptus Mechanicus, tech-priests put aside their tools and girded themselves with the fearsome weapons of their order. In the rubble of burned-out hab-areas, Primarch Jaghatai Khan mustered the White Scars, the Chapter of Space Marines which he had personally instructed in the art of lightning warfare. Three full Titan legions stood ready to defend their Emperor.

As the earth shuddered under the bombardment, tank divisions roared across the tortured landscape to take up their position against the coming invasion. Brave men checked their weapons and offered up last prayers. Defence lasers swivelled to face the turbulent threatening sky. Suddenly, the night was streaked by the plasma contrails of drop-pods. Within the Emperor's halls even the Space Marines shuddered, knowing that they would soon confront their lost and damned brethren. The terrifying prospect of facing these corrupt Primarchs who had sold their souls to Chaos filled every man's mind with indescribable horror and dread.

The pods touched ground and from them erupted the mightiest champions of Chaos, the renegade Space Marines of the lost legions. These were no longer the fine human warriors of legend but twisted creatures, bodies warped by the energies of Chaos, minds twisted by their devotion to the dark powers. If what had happened to the Space Marines was bad then what had happened to their Primarchs was worse. They had been created higher in the Emperor's esteem and had fallen further. None of their former comrades would have recognised them - they had been transformed into creatures both daemonic and exultant.

Mighty Angron bellowed orders to his blood-drinking followers, the World Eaters. Brandishing his great runeswordhe led them against the defenders of Eternity Wall Spaceport. Around his red-armoured followers bolter shots whined. Unflinchingly they advanced, determined to spill blood for the Blood God.

At Mortarion's rasping command, the Death Guard emerged silently from the festering cocoons of their drop-pods and advanced on their terror-stricken foes. The dread runes on Mortarion's scythe glittered eerily in the night as he gestured for them to advance.

Magnus the Red glared triumphantly about him with his one watchful eye before ordering the mage-warriors of the Thousand Sons to cast their spells of doom.

A hail of deadly bolter shells cut down dozens of the Emperor's Children. Undeterred, the wounded howled with pleasure at the experience and chanted the praises of their Primarch, Fulgrim. The renegade Space Marines surged forward to carve a path through their foes.

Perhaps some defenders went mad with fear. Perhaps the corruption of Chaos ran deeper than anyone suspected. Perhaps some were foolish enough to think that they could negotiate with the

ultimate enemy. Whatever the reason, one last vile treachery was to take place. Many units of the Imperial army that had pledged loyalty to the Emperor turned blasphemer even as the Traitor Space Marines made their drop. It was almost as if it were a pre-arranged signal. In one of the basest acts of betrayal in Humanity's history, they turned their weapons on their brother warriors and cut them down like dogs. Thus did the Lions Gate Spaceport fall to the rebels. As the heretics chanted and howled their mad prayers, the air shimmered and slavering daemons emerged from the warp to spread terror and dismay.

Then indeed did it seem to the defenders that they were living in the last days of Mankind. Huge bat-winged Bloodthirsters swept triumphantly across the weeping skies. Clawed Keepers of Secrets danced lasciviously on piles of corpses. Great Unclean Ones chuckled as they lumbered through the ruined streets spreading trails of filth and slime and disease. Enigmatic Lords of Change perched atop the towers and statues and supervised the coming of Chaos to the heart of the world. Mighty ships began the descent from orbit, hoping to overwhelm the defenders by sheer weight of numbers. Unlike the drop-pods, these presented fine targets for the weapons of the defenders. And thus did the battle for Earth begin in earnest.

Defence lasers blasted many renegade ships from the sky, sending thousands of tons of fused metal death raining down onto the ground below. One giant raft span out of control and crashed into a hab-unit, killing a hundred thousand people. Another was welded to the ground, disgorging its passengers into a lake of bubbling tar and plas-crete. The vessel of the Legio Damnatus was vaporised and that Titan Legion's name passed into history. As quickly as they disembarked, the traitors surged forth from the spaceports to besiege the bastions of the defenders. Their first objective was to silence the defence lasers inflicting such casualties on their comrades. The rebels were met by a wave of Imperial defenders, desperate men who knew that they were giving their lives for their home world and their Emperor.

In the tightly packed streets around the spaceports, the fighting was close and deadly. Bolters chattered and missile launchers delivered cargoes of death from building to nearby building. Traitor tanks rumbled through the avenues, turrets swivelling to bring weapons to bear on the hastily improvised barricades of their former comrades.

Soon the defenders of Eternity Wall Spaceport had been swept aside by the merciless assault and the hordes of the Warmaster were in total possession of the space field. More and more intricately wrought drop-ships descended from orbit. They towered over the landing ground like nightmare skyscrapers, the dark runes on their sides glowing evilly in the gloom. Hundred-metre high doors opened in their kilometre-long sides. From their red depths, Titans emerged. They were warped giants; the armour of their carapace fused and moulded into new shapes by the power of Chaos. Within them were men melded to their machines. Some of the hideous Titans had strange and potent weapons, others were a bizarre hybrid of the organic and the machine. Metal tentacles lashed, spiked tails whipped back and forth. Engines roared like the voices of angry beasts. Banners fluttering, the Titans of the Storm Lords and the Flaming Skulls legions marched forth. At Lions Gate Spaceport, the traitors welcomed the towering black war engines of the Khornate host. Monsters, mutants and cultists seethed like angry ants around their bases.

Reinforced by this fresh wave of troops, the hordes swept on, driving through the exhausted and demoralised Imperial troops to the very walls of the Emperor's palace. Khornate warriors howling their bestial war cries raced towards the marble and steel outer ring. Hordes of unstoppable Thousand Sons marched relentlessly forward, bolter fire raking the defenders. Slaaneshi Noise Marines swept aside the Imperial Guard infantry and reached the Saturnine Gate. Round the walls bitter fighting ensued as the Imperial soldiers sallied forth, trying to drive the attackers back before the main body of the assaulting troops arrived. Men died in their thousands. From pillbox emplacements in the palace walls Imperial gun crews rained death down on the relentless attackers. Again and again the streets outside the palace were swept clear of heretics. Again and again new foes stepped forward to take their place.

Now indeed it seemed that the tide of battle had turned against the Emperor. The spaceports were firmly in the grasp of the minions of the Warmaster. Hundreds of thousands of troops poured down from orbit. Gibbering mutants and hideous amorphous Chaos Spawn surged out of the dread ships. Under the banner of the great eye, the sign of Horus, the lackeys of the four great powers of Chaos marched united. Mounted in Rhinos, lurking within mighty behemoths and clinging to the sides of gigantic war-engines, they made their way en masse to the Emperor's palace.

Looking down on the seething sea of foulness, the defenders' hearts went cold. Mingling with the daemons and the mad-eyed cultists and the mutants, they could see heretical Space Marines and traitor Guardsmen. These were people they might have once fought alongside, who had once been as loyal to the Emperor as themselves. They looked upon a dark mirror of their souls. Down there they could see martial honour become berserk madness, human cleverness become sly treachery, hope become foulness and love become abominable lust. The brave men on the walls knew that there was no way out. Here they must stand and fight and die. There would be no mercy from those below.

This was a war where there could be no honourable peace. It was destroy or be destroyed. For a moment all was silence, then Angron strode forth. In his brazen voice he demanded that the loyalists surrender. He told them that their cause was hopeless, as they faced a foe which could not be defeated. They were cut off, outnumbered, and defending a ruler too weak to be worthy of their loyalty. In that moment the men on the walls felt their resolve weaken. Looking at the transformed face of the Primarch who had once been one of the Emperor's finest warriors, they saw an invincible, relentless foe backed by a numberless horde and all the daemonic might of Chaos.

There was a clamour on the walls as Sanguinius and the Blood Angels arrived. Standing on the wall, the angel-winged Primarch glared on Angron with angry contempt. For long moments their gazes locked, each Primarch seemed to be measuring the other, searching for chinks in the armour, for any sign of weakness and lack of resolve. Who knows what they saw there? Perhaps they communicated telepathically, brother Primarch to brother Primarch. The truth will never be known. Eventually Angron turned and walked back to his lines. He told his troops that there would be no surrender; they should kill everyone they found within the palace. No stone should be left upon stone.

With a roar the horde advanced towards the walls. Great Lords of Battle lurched forward on iron wheels, crushing anything in their way, unloading racks of missiles and turning the area on the top of the walls into blazing storms of death. Doom Burners sent tongues of superheated metal licking out at the emplacements. Molten brass filtered through the windows and scalded those inside. Multi-tracked Cauldrons of Blood squirted jets of obscene daemonic ichor onto the defenders. Enormous Flesh Hounds of Khorne loped forward in their wake. Titans armed with specially constructed siege weapons lumbered into position. Battle cruisers dropped megatons of explosive death onto the defenders.

Every loyal warrior knew that he was already dead, that there was no way he could survive the coming of the daemonic army. The soldiers fought with the desperate ferocity of hopeless men, firing until their weapons were empty, snatching up the bolters of the fallen, and facing monsters with the butts of their guns when all ammunition was exhausted. Three times the horde managed to scale the walls, and three times it was driven off by the valiant efforts of Sanguinius and the Blood Angels. Wearily the Primarch marshalled the defenders, rallying the broken, speaking words of comfort to the mortally wounded, fighting with cold, implacable fury when he was called upon to do so. Slowly though, despite his efforts, the Chaos forces managed to erode the defence. They seemed numberless as the grains of sand on a sea shore and Horus spent their lives carelessly.

Outside the walls, Imperial forces frantically raced from their bastions to try to relieve the palace. Titan legions boldly cut their way towards the centre of the rebel army. The White Scars Space Marines harried its flanks. No attempt to break the rebel line succeeded. Breaking through that blood-mad horde was a near impossible task. All four of the daemonic Primarchs inspired their followers to feats of fiendish bravery. For every Chaos warrior who died it seemed that two more stood ready to take his place.

In orbit, the Warmaster watched approvingly. If the palace fell and the Emperor died, loyalist legions across the galaxy would lose heart and the war would be over. Without the psychic shield of the Emperor's power, Humanity would swiftly fall prey to Chaos. Horus would stand triumphant amid the rubble of Humanity's greatest empire. He would become a new and angry god. If he did not win soon, reinforcements would filter in from the corners of the Imperium, and his attack would falter. For the Warmaster this was the desperate, ultimate gamble. Everything was staked on this attack. It had to succeed, and at that moment it looked as if it might.

Day by day the siege wore on, casualties rose from the thousands to tens of thousands to hundreds of thousands. Bodies had to be bulldozed from the access ways to the Saturnine Gate by war machines. Chaos Titans blazed at the walls, specially constructed missiles ripping great chunks from the masonry. The Titans of the Fire Wasps answered their fire with volcano cannons. The smell of burning flesh filled the air as the corpses of the dead were incinerated in funeral pyres a hundred foot high. Obscene ash parched the throats of the defenders. The World Eaters built a pyramid of scorched skulls sixty foot high in Temple Square. By night the chants of degenerate cultists echoed through the streets and daemons flitted among the ruins of Earth.

Slowly, foot by torturous foot, the defenders were forced back. The great walls of the palace were riddled with hundreds of kilometres of bulkheads and corridor. Within this maze, bitter hand-to-hand fighting ensued until entire sections of passage were filled with bloated corpses. Feeling that progress was too slow, Horus ordered the Titans of the Death's Head Legion to demolish

entire sections of the wall. Despite taking tremendous casualties, the great Warlord Titans broke through, and the forces of the Warmaster flooded into the palace grounds.

While all this was taking place, Jaghatai Khan of the White Scars had implemented a change of plan. Rather than throwing away his forces against the near invincible bulk of the main Chaos army, he launched a lightning raid against Lions Gate Spaceport. This night attack was spearheaded by the savage warriors of the White Scars, who led the remnants of the 1st Tank Division and elements of the surviving Guard armies against the surprised heretics. Khan threw a defensive perimeter around the spaceport and held it against all counter-attacks. The flow of men and materials towards the palace was halved at a stroke.

This success gave heart to the defenders. They swiftly attempted to seize Eternity Wall Spaceport, but here the forces of the Warmaster were better prepared. The attackers were ambushed and driven back by traitors. Horus knew it was imperative to keep his beachhead secure. The final push on the inner palace had begun.

The battle raged across the grounds of the Inner Gardens. What had once been a vast parkland was swiftly turned into a killing ground. Men used statues for cover and monuments for bunkers. Blood swirled in the waters of the ornamental lakes. Groves of ancient redwoods burned. The smell of the burning mingled with the acrid odours of weapons and engines and death. Red-eyed, snatching sleep when they could, both sides fought a total war. Trenches were hurriedly excavated in the meadows. Snipers killed men as they tried to sip brackish water from the ruined fountains.

Both sides fought with unimaginable naked ferocity. Both sides sensed that the end was near.

Eventually Sanguinius was forced to retreat to within the palace itself, personally holding the Ultimate Gate against the oncoming horde while the last of his wounded men was carried through. Just as the giant ceramite gate was about to close, a Bloodthirster of Khorne leapt upon him and the daemon's huge talons closed around Sanguinius' throat. The Primarch took to the air, angel and daemon wrestling over the warring armies. Both sides halted for a moment to watch the titanic struggle. It was a conflict such as has been rarefy seen; two beings of awesome power wrestling above them.

Sanguinius was weary and near the end of his strength, and the daemon gouged great wounds in his flesh. The heretical throng roared its approval as the Primarch was cast to the ground, the

impact splintering the granite. For a moment the Primarch lay still and a groan rose from the Blood Angels as the daemon stood over him and howled in exultation. Then slowly and painfully the Blood Angels' Primarch rose and seized the creature, raised it high and broke its back across his knee. Then, with a halo of power playing round his head, he tossed its broken carcass back amid its followers. They beat their chests and rent their hair and wailed in dismay as the Ultimate Gate shut.

Above, the great Sky Fortress bore Rogal Dorn and the remnants of the Imperial Fists to the inner palace. The loyal Primarch was determined to stand and die with his Emperor in the final hour. The Sky Fortress then raced away from the palace in a desperate attempt to reach Jaghatai Khan and return him to the palace. It was destroyed by a blaze of fire from the Death's Head Titan Legion. Even in death its commander wrought havoc on the enemy, bringing the crippled vehicle down into the centre of the Chaos horde. It seemed as if a new sun was born on Earth as the plasma reactor exploded, blasting out a crater three kilometres across. Those within the palace knew they were cut off; now they were truly alone. Only a miracle could save them.

Now the final siege began. Through great breaches in the outer walls more and more armaments and reinforcements were brought to bear. The Warmaster himself prepared to teleport down to the surface and supervise the destruction of his former lord. Then a daemon from the Warp whispered to him the words that he had dreaded. A loyalist fleet under Leman Russ and Lion El'Johnson bearing a fresh army of Space Wolves and Dark Angels was only hours away. It would take days to break Humanity's last citadel, even with Horus leading his troops. It seemed that time had run out for the Warmaster, that his gamble had failed.

Horus was first among the fallen, with the power of a god and the cunning of a daemon. He resolved to try one final desperate gambit. He could still kill the Emperor. He ordered all comm-net communications blocked so that the defenders would get no word from their rescuers and then he used his psychic powers to the full to prevent the Emperor becoming aware of this. Finally he dropped the shields of his command ship. It was an invitation and a personal challenge that he knew the Emperor could not resist. He was being offered a chance finally to smite the foe who had harried him for so long.

The Emperor rose to the challenge, and he and his surviving Primarchs teleported aboard the Warmaster's battle barge. Horus used his powers to separate the Emperor from his loyal followers. The loyalists were transported to different spots within his hideously altered ship. Sanguinius fought his way directly to Horus' throne room. In his evil cunning the Warmaster offered the Blood Angel a chance to switch sides, reasoning that the winged Primarch's followers would be useful when the Space Wolves and the Dark Angels arrived.

Sanguinius refused. Horus grew wrathful and attacked him. At the peak of his powers the Blood Angel would have been no match for the Warmaster and now, sorely wounded and weary, he had no chance at all. Horus strangled him with his bare hands before the throne which the powers of Chaos had gifted him with.

The Emperor found Horus shortly after this and what happened next is the subject of legend. The two mightiest beings in the history of Mankind clashed. They met blade to blade, power to power, mind to mind and tested sinew and psychic ability to the ultimate. Behind Horus was the massed power of the Chaos gods. The Emperor stood alone and still he triumphed, though he was terribly wounded in the process.

The psychic shock wave of the Warmaster's passing rippled outward through the warp. On Earth, daemons screamed and vanished, and the rebel Primarchs stood dumbfounded. It was their leader, not their enemy's, who was dead and they knew it. With the one who had raised the banner of rebellion dead, there was nothing to hold the rebels together. They were demoralised and dismayed. When word of the oncoming Imperial fleet reached them they knew that they must flee.

Within the perimeter of Lions Gate Spaceport, Jaghatai Khan and the handful of unwounded White Scars watched in amazement as the horde halted in confusion then retreated. Angron, Fulgrim, Magnus the Red and Mortarion led their men to their ships and departed, leaving the deluded, traitorous followers of Chaos to their fate. As he stepped aboard his ship, Angron turned and shook his fist at the glittering dome of the Imperial palace that had proved just out of his taloned reach.

Then he shrugged; he and his fellow rebels had all eternity to seek revenge. The Battle for Earth was effectively over. The Horus Heresy was ended. Rogal Dorn found the Emperor's broken body in the ruins of the Warmaster's throne room. Through mangled lips, the Emperor whispered instructions for the creation of his golden throne. Dorn smiled, for while the Emperor still lived there was still hope.

The veteran Primarch returned to Earth. There was much to be done.