The Titans led the way. Around them, columns of tanks and troop transports. Some of the artillery continued to fire, namely that part of it that could be certain to hit the walls and not the advancing Ultramarine columns.
Justinian Thexilev was not enormously fond of being locked in a Rhino - especially not when engaged in a war as ritualistic as this one. It felt restricting. Nevertheless, he was an Ultramarine, and the theoreticals made it clear enough how to approach this specific situation. They were not, no matter how it sometimes felt, the heroes of legend; they were the heroes of reality, and that generally meant following protocol.
Of course, against another of the Legions, it was always good to keep some surprises in store. That was not even a philosophical point; it was, if anything, a rather obvious theoretical. Whether or not one held to the Imperial Truth, whichever master or cause one fought for - it was a universal law of warfare that predictability was a losing strategy.
Which was to say, in the practical, that the Ultramarines had prepared surprises for their foe, as that foe no doubt had for them.
The citadel's walls had been built well, but even so they were crumbling under the barrage. There was no single, massive breach, but there were numerous weak points. It was to one of those, in the northwest protrusion of the fortress, that Thexilev's column now advanced.
The Salamanders had gathered to meet them, under a wall of guns that was backlit by that eternal golden beacon. Yet that fire was scattered. The Titans - two Reavers and five Warhounds in their column - buckled under the blows, but did not come close to toppling. The Rhinos, especially those near the front line, fared worse. One exploded in a small fireball, taking the Astartes inside with it.
Thexilev nodded, mentally honoring those brothers and knowing they would not be the last. They were fighting a cornered foe today. Their objective was nothing less than the extermination of every World Eater and Salamander on Nuceria. And with that, perhaps, the Warp Storm that raged above them would dissipate, and they could return to whatever was left of Ultramar. It could not have been destroyed, not yet. Not so quickly.
Unfortunately, though, Thexilev knew exactly how easily the impossible could become reality in this war.
The Titans slowed as they neared their walls, turning their guns on the enemy emplacements. Those broke, but not easily. The Titans' pace allowed some of the Rhinos to ride ahead, charging towards the wall in a mad dash to dispel their cargo.
Thexilev smiled in the knowledge of exactly what that cargo was.
The void shields were down - had been down, for a time - but the Salamanders built well. For all that the Eighteenth was not a siegemaster Legion, walls and roof alike had remained mostly intact despite the barrage. And now, the Salamanders stood on those walls, laying down a field of fire. Yet the Rhinos kept charging, because of course the theoretical of Salamanders using fire was well-known, and abundant insulation had been added to the transports' interior.
Still, eventually one went up. The explosion was brilliant, rattling the ground below, and the Salamanders switched to ballistic heavy weaponry as quickly as they could, because they realized that Rhino engines were not nearly that volatile, meaning that these were not piloted Rhinos, but rather explosive rams. Bombs, driven at the walls to craft a breach.
They were quick enough to down four more at a safe distance. But the remaining transports sacrificed themselves, slamming straight into the wall and going up in great bursts. Rock and metal and more complex composites caved, in avalanches that dragged green-armored Astartes out of the safety of their alcoves and into range of the Titans' strides. It was like a rockfall unearthing veins of green ore - a metaphor that the Salamanders would appreciate, Thexilev considered.
The Titans stepped on the Salamanders, grinding them beneath their feet, and laid down a curtain of fire in front of them before lifting it to fire over the walls at the roof in the citadel's center. As they did so, Thexilev received and belayed the vox order, and the second line of Rhinos opened to reveal their Astartes.
Four thousand Ultramarines charged. Modoleo, Damocles, and Cestus with their Companies remained in reserve. The Salamanders' defense was scattered, unable to keep up. Monaxi drove hardest, his ceremonial crest (pierced by two bolter shells) already visible at the top of the rocks as he directed his company from the height, a shieldwall ahead of him. Ventanus and Auguston led their companies up as well.
Thexilev called the Second to him. "Third breach from the edge," he ordered as he jumped out of the Rhino. Then it was the climb, fire washing down around the Ultramarines, though Thexilev was shielded from the worst of it by the bodies ahead of him.
The schematics were rough, but from the exterior of the citadel it was easy enough to work out likely chokepoints. Easy enough, too, to see that many of them would be useless due to the sheer number of breaches. Coordinating with Ventanus, who held the adjacent breach, Thexilev ordered Pezanzan and Onill to lead simultaneous teams on two levels, to link up with sergeants from the Fourth.
"This seems too easy," he voxed Ventanus.
"It's bloody work," Ventanus said. "Though you might be right."
Thexilev wasn't sure of the theoretical that made this a trap, though. They had the foothold, and while he ordered Ixiosph to remain near the breach and construct counter-barricades, it seemed almost too much caution. They were taking casualties, after all, albeit fewer than the defenders, and it wasn't usually a bad sign that everything was going according to theoretical.
Still, for the sake of completeness, he tried to check in with the other attack vectors. Not much came back. From what little he got, though, the Ninth and Tenth Chapters were finding progress substantially more difficult than they were.
"Theoretical:" he voxed to the other captains, "it's a trap."
"It's gone according to theoretical," Auguston protested.
Auguston, of course, understood immediately. "But the most likely theoretical if this is a trap is that we should advance quickly, to break out."
"Agreed," Monaxi said, once the aggressive captain was out of the thick of it. "Alternative theoretical is that they're concentrating in the center, for ritual purposes."
Both of those were reasonable theoreticals that agreed with their current practical. But then, that was exactly why Thexilev remained suspicious.
He called up Modoleo regardless, now that the walls were silenced. And he ordered Ixiosph to lead the further advance, while he fortified the foothold they'd earned. He briefly helped with a barricade himself, before leading Squad Idospev up a staircase in shooting down sentry turrets from a distance. As he did so, he saw Pezanzan and Onill finally link up with the Fourth, as Ventanus's men cleared the outer point of the fortifications.
And as all that blew around Thexilev in a great gale, the traditional whirlwind of battle, the Ultramarines' Second Captain walked up to the wing's abandoned command center. It was well-armored enough that doing so posed no danger, but upon entering, Thexilev observed that it had already been disconnected.
Still, the visual at least was still available, a view of the top of the spoke leading centerward, the sound of bolter fire even now marking Monaxi's and Auguston's position along it. And at the end of it, kilometers away, a dome, and from it a golden knife slicing the heavens, and making them bleed with the foulness of the Warp.
And backlit by that knife, charging down a walkway from it, at the head of a green-armored column of Astartes and vehicles -
Thexilev shouted out a warning, but it was too late. Monaxi's and Auguston's companies would take the brunt of it. The Titans were coming up, they could respond, drive them back, and against almost any number of Astartes they could have held the line even without them.
But not against a Primarch.
Vulkan had always been physically largest of the Primarchs, but now he entirely dwarfed the Astartes behind him, less a warrior and more a war machine. His hammer seemed undersized for his crackling hands. Around him, the air seemed to spark with, presumably, his psychic power. Yet his onyx form and viridian armor also seemed protean, shifting to and fro like the Emperor or the Crimson King, in a matter most atypical of the most grounded Primarch.
Around him, psychic imprints swirled. To Thexilev, they seemed to etch scenes into the air. Faint images, of a sallow-faced man holding out on his hunger strike despite his captors' indifference, of a woman's face as she slowly realizes her lover has betrayed her and taken everything she had, of bioengineered faceless swarms causing worlds' worth of painful death. Thexilev did not look at them for long - he'd fought Chaos before, he knew procedure - but he still saw, before Vulkan's column descended under cover, as they screamed and stretched in rhythm with the blows of his hammer. Ultramarine bodies flew away, throwing up bursts of sand as they fell. Monaxi was the first, buying time for his company to retreat.
A shell exploded on the roof above Thexilev, but the ceiling held. He ignored it, focusing on voxing commands to Ixiosph. The barricades would hold for long enough - there would be a slaughter before them, but the Titans were already near. Ixiosph, and Auguston who had retreated into position, would hold. That was the theoretical - but practicals with a Primarch around were never certain. Thexilev took in a deep breath, waiting for the wedge of green to drive itself into the defensive line.
It never did. The Salamanders, as Thexilev learned from vox-traffic, focused on mopping up stranded squads. "They saw the Titans coming," Auguston hypothesized.
"They're hemmed in," Thexilev said. "They needed the breakthrough."
"They're trying something," Auguston said. His voice was sore. The runes indicated that half of the First Company had been lost within minutes, and more of the Third. The Second had fared better, but Thexilev still had to restrain himself as the reports came in. Naxigum and Onon's deaths, along with their entire squads, stung worst.
What had they died for? Thexilev strained at the schematics, averting his eyes from the great golden beacon, in search of an answer. Nothing emerged, no strategic aim, and so his attention wandered. What had they died for? Not what they had died against. That was a question of an elementary answer. But what the Coalition stood for... that was why Guilliman's Imperium Secundus had been meant to define. Only it had not had time to do so.
Was this how primitive natives felt when the Imperium came to their worlds? A new world opened, one they did not have the base of knowledge to understand. So the savages continued according to set patterns, even when those set patterns were obsolete.
If not for Guilliman, Thexilev might even have believed that.
It was something in the air, perhaps. An ululating thrum of despair. But Thexilev knew, trusted, that his Primarch had the solution. Not all of it, not yet, but where minds like Thexilev's recoiled at all their assumptions being overturned Guilliman's was already processing the way to victory. As to Thexilev and the Ultramarines, it sufficed to hold the line in the meantime.
But still, Thexilev was too good a student of the Imperial Truth not to doubt. Yet training took over. He kept up the vox-chatter, even as Vulkan bore down on one last isolated band of Ultramarines -
And then, suddenly, it was dark.
At first Thexilev thought it was the power, but there had been no power in this room in the first place. Then, an absurd thought, that it had been the sun. It had not been, as one glance up and into the storm proved.
No, the skies above had not changed, and it took Justinian Thexilev a few moments to realize what had.
Ahead, in the center of the enemy complex designated Ghanun Fortress, the beam of golden light that had pierced through Nuceria's very core, that had shone undimmed for nearly three Terran months, had in one instant gone out.