The first virus bombs detonated high above Choral City, unleashing massive explosions that scattered their lethal payloads throughout the atmosphere.
These viral strains, released on Isstvan III, were the most effective killers in Horus's arsenal, engineered to annihilate every living thing on the planet's surface. The bombs possessed a yield capable of destroying the planet a hundred times over, set to explode at various altitudes and locations across its surface.
The virus swept through forests and plains, travelled along algal blooms, and rode air currents across the globe. It crossed mountains, forged rivers, and burrowed through glaciers.
The Emperor had been reluctant to use such deadly weapons, even though they were among the Imperium's most formidable tools.
The bombs fell all across Isstvan III, but most of all, they fell on the Choral City.
...
The World Eaters were caught the furthest out from any real cover and suffered the absolute worst of the initial bombardment. A few under Captain Ehrlen had managed to dive into the safety of the heavy bunkers, but far more were left stranded in the open plaza.
Tarvitz had reached them in the nick of time, but that span was truly short.
Mighty bioengineered warriors, capable of waltzing through the most gruelling of battlefields, dropped heavily to their knees as the flesh-eating virus chewed right through their armoured suits.
The deadly, corrosive chemical agents woven into the weapon's design dissolved the exposed rubber pipes and flexible armour joints, while easily finding their way inside through any cracks or battle damage the Marines had taken during the fighting.
"ARGH!!"
Space Marines began to scream.
The sound of their agony was shocking simply because it existed at all. Astartes were engineered not to feel fear or display pain, so to hear them scream that way was horrific.
The bioweapon completely broke down cellular bonds at a microscopic level. Within mere minutes of breathing it in, the victims literally dissolved into a boiling soup of liquid flesh, leaving behind nothing but sloshing suits of white-and-blue armour filled with rot.
Even many of the soldiers who had successfully scrambled into the sealed bunkers died in absolute agony; they had shut the heavy blast doors behind them, completely unaware that they had carried the invisible, airborne plague inside the clean room with them.
The virus tore through the civilian population of Isstvan III at the speed of thought, jumping from person to person in the mere second it took to breathe in the foul, invisible cloud.
People dropped dead exactly where they stood. Their skin and muscles sloughed completely off their skeletons as their entire nervous systems collapsed and their bones melted to the consistency of jelly.
It was a gruesome sight. One for nightmares.
Brilliant, chemical explosions from the falling bombs fed the spreading plague, keeping the fatal reactions of cellular decay moving across the city like a wave. And that was necessary.
Ironically, the virus's extreme lethality was its own worst enemy. Because it killed its hosts so quickly, it ran the risk of burning itself out, lacking living bodies to carry it further across the landscape. That was also why the flesh-eating virus couldn't exist on its own and would never spread.
Well... that was until now.
To counter this 'weakness', if you wanted to call it that, the unrelenting bombardment from the traitor fleet in orbit never stopped. The warships smothered the entire planet in a precisely targeted grid of overlapping fire plans, ensuring that absolutely no corner of the world could escape the reach of the virus.
Entire kingdoms, cities, and nations across the planet's surface were completely wiped out in minutes. Ancient human cultures that had successfully survived the thousands of years of Old Night and endured the horror of alien invasions a dozen times over fell in an instant without ever knowing why.
Millions died in screaming terror as their own bodies betrayed them and fell apart, reducing a thriving world into nothing but a silent, decaying mass of organic waste.
It was abhorrent.
...
A single figure ran across the trenches. Alexei had felt the virus approach and, naturally, hadn't felt endangered. That was until his power suit began to be affected as well, and he had to act to stop the melting of his armour joints.
The screaming of the Choral City's death throes came in massive waves, battering against the heavy stone walls of the Precentor's Palace like a tsunami. In the streets down below and throughout the grand palace corridors, the people of the Choral City were decaying exactly where they stood, their bodies completely coming apart in torrents of dissolving flesh.
Alexei took deep breaths as he rushed across the battlefield, looking for more Astartes who hadn't yet been turned to jelly. And he found a group of them right in front of him.
Increasing his speed further, pushing past his previous limits, he arrived as they were screaming in terror and pain. Alexei reached the first World Eater and held his head. A fine blue steam was released through his helmet and penetrated the Astartes' power armour in a moment.
The immense shaking and the dissolving of the biological matter suddenly stopped, and the Space Marine fell flat on his face. Alexei ignored him and moved to the others, who were already dissolving. He quickly repeated the action and spread the blue cloud, making it reach them all before they too fell to the ground.
It took a moment before the World Eaters groaned and pushed themselves up again.
"What... was that?" he asked. "Huh?!"
"Brother... the sky... my mind..."
"It's so... quiet."
"Free."
The World Eaters suddenly looked at Alexei in shock. Not all World Eaters had the Butcher's Nails implanted, but these four before him had. The flesh-eating virus had a very nasty effect, dissolving biological matter at a molecular level, but this had an unforeseen, fortunate side-effect.
"What have you done?"
"The virus dissolved your bodies. I have created a counter-virus that attacks and neutralises the flesh-eater's effects. It seems that due to the flesh-eater, the butcher's nails simply fell out, and now, after being free from it, you have gained something unexpected. Although the damage that you already suffered won't be healed, sadly, it will allow you to make it to the bunkers."
Alexei didn't wait for thanks, knowing that would never come anyway, and he didn't want to waste any more time. He had to find more Astartes who hadn't made it in time and spread his counter virus further.
The citizens of Isstvan III ran into the wide avenues to die, crying out their deep hatred and terror up at the dark sky, begging their gods to deliver them from the nightmare in vain. Millions of people screamed out all at once, and the result was a terrible, black-stained wind of pure death.
A Warsinger soared briefly overhead through the smoke, desperately trying to ease the agony and terror of their final moments with her soothing songs. But the airborne virus found her, too.
Instead of singing the praises of Isstvan's gods, she coughed out thick, black plumes of rot and blood as the plague tore right through her internal organs. She fell out of the sky like a shot bird, toward the sea of dying people below.
A massive, bulky shape appeared on the high roof of the Precentor's Palace. Ancient Rylanor, who was entombed in a dreadnought, strode to the very edge of the stone roof, overlooking the scenes of absolute horror in the square below, watching the viral carnage boiling between the grand buildings.
Rylanor's massive Dreadnought hull was completely sealed against the world outside, sealed far more effectively than any standard Space Marine armour.
Because of this, the deathly, toxic wind swirled harmlessly around his armoured plating as he watched the city's destruction unfold.
He looked straight up toward the morning sky, where far above the cloud layer, the Warmaster's massive fleet was still emptying the last of its deadly payload onto Isstvan III.
The ancient Dreadnought stood completely alone on the rooftop, the only silent note of peace in the middle of the screaming horror of the Choral City's death until, by chance, he saw a figure rush across the battlefield, far in the distance to the west of the palace.
It seemed a single Astartes still lived for some reason... but how? Slowly, although that was as fast as he could move, he started to make his way down and towards that figure, hoping to find at least one of his brothers alive.
.
"Good job we built these bunkers tough," said Captain Ehrlen.
The deep darkness of the completely sealed bunker was only made worse by the horrific sounds of mass death echoing from beyond its thick concrete walls.
Pitifully few of the World Eaters had managed to reach the safety of the bunker network located at the edge of the trench lines and barricade themselves safely inside.
Although they were more than if Travitz hadn't warned them, it was still embarrassingly few.
They waited quietly in the dark, listening to the flesh-eater virus killing off the city's remaining population and their unfortunate brothers who hadn't made it to safety, far more efficiently than even their chainaxes ever could.
Tarvitz waited among the blood-drenched warriors, listening to the agonising deaths of millions of people in mute horror. The World Eaters appeared to be entirely unmoved by the catastrophe, as the deaths of civilian populations meant absolutely nothing to their brutal mindset.
Outside, the horrific screaming was finally dying down, quickly replaced by a dull, low moaning. Pain and intense fear mingled together into a distant, constant roar of a slow, planet-wide death.
It was almost unbearable.
"How much longer must we hide like rats in the dark?" demanded Ehrlen, with growing impatience.
"The virus will burn itself out quickly," said Tarvitz, trying to keep his voice steady. "That's exactly what it's designed to do: eat away anything living and rapidly leave a completely clear battlefield for the enemy to take over."
"How do you know?" asked Ehrlen.
Tarvitz looked back at him through the dim light. He could have told Ehrlen the absolute truth about the fleet above, and he knew that the loyal captain fully deserved to hear it. But what good would it actually do right now?
The unstable World Eaters might snap and kill him on the spot just for saying it out loud. After all, their own beloved gene-father, Angron, was a core part of the Warmaster's massive conspiracy.
They had trusted him, saw him as the ultimate form of a warrior and wanted nothing more than to be loved, or at least accepted by him, more so than any other Space Marine Legion.
They had implanted the Butcher's Nails for him! They killed for him, they died for him!
No, if Travitz said that Angron was part of this, they would rip him to shreds and not even the few Death Guard could or would help him then.
"I have seen such weapons employed before," Tarvitz lied quietly.
"You had better be right," snarled Ehrlen, sounding far from satisfied with Tarvitz's brief answer. "I won't cower here for much longer!"
The mutilated World Eater captain looked over his remaining warriors, their bloodstained armoured bodies packed tightly together in the cramped, pitch-black space of the bunker. There were Death Guard among them as well, but more had made it to other bunkers further away, to give them the space they needed.
Ehrlen raised his heavy, blood-clotted axe and called out into the dark to his brothers.
"Wrathe! Have you reached the Sons of Horus on the vox?"
"Not yet," replied Wrathe.
Tarvitz could easily see that the speaker was a veteran, with numerous cybernetic cortical implants blistered like metal studs across his shaved scalp.
"There's some radio chatter on the wider bands, but nothing direct or clear."
"So they're still alive out there?"
"Maybe."
"What about you, Death Guard? Have you heard anything?" he asked.
"It's much of the same, nothing concrete."
Ehrlen shook his scarred head in bitter disappointment. He hated not being able to do anything most of all.
"They got us. We completely thought we'd taken this city, and they got us."
"None of us could have known," said Tarvitz gently.
"No. There are no excuses," Ehrlen's face hardened into an unyielding mask. "The World Eaters must always go further than the enemy. When they attack us, we charge right back at them. When they dig into positions, we dig them out. When they kill our warriors, we destroy their cities. But this time, the enemy went much further than we did. We attacked their city, and they destroyed it entirely just to take us down with them."
"We were all caught out, captain," said Tarvitz, trying to share the burden. "The Emperor's Children, too."
"And the Death Guard."
"No, Tarvitz, this was strictly our fight. The Emperor's Children and the Sons of Horus were sent to behead the beast, but we were the ones sent to cut its heart out. This was a stubborn enemy that could not be scared away or thrown into confusion by tactical manoeuvres.
The Isstvanians simply had to be killed. Whether the other Legions want to acknowledge it or not, the World Eaters were the ones who had to win this city, and we take full responsibility for our failures."
"It's not your responsibility," said Tarvitz, his heart breaking for the betrayed captain.
He looked at the Death Guard, and they looked at him in that moment. Both sides knew and understood what they wanted to tell the poor man in that moment. But nothing they said would make him feel better.
On the contrary, it would make him more miserable.
"A lesser soldier pretends that his failures are those of his commanders," said Ehrlen coldly. "An Astartes realises they are his alone."
"No, captain," said Tarvitz, his desperation rising. "You don't understand. I mean--"
"Got something," said Wrathe suddenly from the far corner of the bunker, interrupting the conversation.
"The Sons of Horus?" asked Ehrlen, turning quickly.
Wrathe shook his head and looked at their brother Legionnaires.
"Death Guard. They took cover in the bunkers further west."
Deep within that western trench sector, Alexei's digital vox-virus was actively linking his brothers' networks. He had deliberately opened a secure, low-frequency data stream from his position to let the surviving pockets of loyalists know they weren't alone and to coordinate the counterattack as soon as the time came.
"What do they say?" Ehrlen demanded.
"Apparently, the virus is dying down," Wrathe reported, reading the scrolling data on his display.
"Then we could be out there again soon," said Ehrlen with immediate relish, a dark, bloodthirsty smile returning to his disfigured face. "If the Isstvanians try to come and take their city back, they'll find us waiting for them in the ruins."
"No," Tarvitz said, his voice dropping into a hollow, terrifying whisper that made the packed room go completely silent. "There's one more stage of the viral attack still to come."
"What's that?" demanded Ehrlen.
"The firestorm," said Tarvitz.