Defence of Ryza
At the outbreak of the Heresy, Ryza stood firmly loyal and purged itself of Kelbor-Hal's traitorous sect. The Forge World soon became known as an isolated loyalist outpost amongst traitor territory, serving as a refuge and production centre for the forces of the Emperor. For a time the traitors were content to ignore Ryza, but upon Horus' drive into Segmentum Solar the bastion could no longer be allowed to remain free. So it was when Horus ordered Ryza be captured it was home to not only the Legio Crucius but also other Titan Legions and Knight Houses such as House Taranis, House Zavora, Legio Honorum, and Legio Osedax. These were commanded by Hierophant Technis Nira Heldentum. Yet despite this power the loyalist forces still paled in comparison to the Dark Mechanicum invasion force under the command of Yuritus Omnicron, Fabricator-Locum of Estaban VII. His forces included elements from the Legio Magna, Legio Vulturum, and Legio Mortis as well as the Renegade Knight houses of House Morbidia and House Oroborn. With them came massed traitor Taghmata forces mustered from the Beta-Garmon Cluster.
The arrival of the traitor vanguard was heralded by anomalous sensor readings in the weeks preceding the invasion. These readings produced many false alarms of enemy contact and were ultimately blamed on Warp Storms. In truth however over a dozen traitor vessels moved towards Ryza. These were modified Mechanicum Cruisers whose entire interiors had been removed to create additional cargo bays laden with lobotomized warriors, tainted Skitarii, and horrifying mechanical creations. A full month passed before these ships quietly reached Ryza Secundus, the artificial moon orbiting Ryza. Simultaneously a traitor armada of 130 vessels arrived in the Ryza System, dwarfing the loyalist fleet of 20. As the loyalists saw the approaching traitor fleet they failed to notice the vanguard infiltration force which was able to assault Ryza Secundus. Despite taking heavy anti-aircraft fire the traitor vessels were able to land substantial forces on Ryza's surface via boarding craft. Against this wave of attackers, the loyalists sent Skitarii and a dozen House Vornherr Knights. The loyalists resisted fiercely but were overwhelmed, allowing House Morbidia Knights to land. The Vornherr knights fought to the death over a six-hour engagement, taking down a score of enemy Knight engines. Their sacrifice allowed Ryza Secundus to further punish the traitor fleet with its plasma batteries before finally being silenced.
With Ryza Secundus captured by the traitors, the remaining loyalist ships fled to prearranged locations outside of the system to gather allies and return in force. Uncontested, the traitors entered Ryza's orbit and activated their sleeper cells across the planet. Pro-traitor elements on Ryza rose up, leading worker revolts and committing acts of sabotage. The fatal blow, however, came 19 days later when a rogue Tech-Priest seized control of a forge-fane on the southern continent close to the vital Conveyance Terminus Nine-Omega Spaceport. The captured Forge-Fane contained over ten Stormblade tanks, causing a Legio Honorum battlegroup to move against them. It thus fell to House Ioeden to defend the spaceport, and it was then that the traitors struck. House Ioeden revealed their treacherous nature and turned upon the Legio Honorum as it rushed to return. Loyalist Princeps Seniores Galxexu of the Legio Honorum ordered his Titans to unleash their guns upon the spaceport before withdrawing, destroying the vital infrastructure to keep it out of traitor hands. By the time the loyalists retreated only two Warlord Titans of the Legio Honorum remained. The door to Ryza was now open.
The traitors next struck at Salvation Isthmus, an artificial land strip formed from metal and rockrete and lined with manufactoria that connected the southern and northern continent across the Sea of Reclamation. Here the loyalists were led by the Legio Crucius. Against them stood the Legio Vulturum. Though outnumbered two-to-one the Crucius Warlord Titans duelled with Vulturum Reavers. The advancing traitors were further ambushed by loyalist Warhound Titans emerging from the shadows surrounding buildings. What began as a bold assault intended to secure a quick victory soon turned into a war of attrition, the Traitors punished for each step they gained. Further advantage was offered to the Loyalists by the Warmonger fortress constructed alongside the northern edge of Salvation Isthmus, its repair cradles offering succour to those Titans of Legio Crucius wounded in battle and providing safe haven to undergo repairs before returning to the fight once more. Four 8 days this battle raged until Princeps Ultima Scrindus Tepfra of the Gore Crows realized that the Legio Osedax was gathering to the west to attack his exposed flank. Refusing to remain stalled, he embarked upon a bold strategy. He ordered his Legio Magna allies forward to draw the attention of the Warmongers while he marched into the Sea of Reclamation itself, submersing their engines and emerging on the loyalist northern flank. Though several engines were lost in the hostile waters the result was devastating for the Warmongers. Many loyalist Titans in repair were lost and with much reluctance the Princeps Ultima Hendril ordered a withdrawal. Those upon the northern continent withdrew, leaving their brothers to death and moving west towards the Forge City of Prosperity.
As the Isthmus fell three loyalist Warhounds (Endless Revelation, Hound of Erudition, and Remembered Glory) managed to bring down the traitor Warlords Cordis Ignis and Barren Ashes. The resulting explosion claimed the lives of the loyalists as well as the enemy Reaver Titan Blaze of Wrath. After running out of ammunition the Warmonger Reaver Beast of Ryza rammed its Gore Crows foes, claiming two engine kills before being laid low. The last of the Legio Crucius to fall was the Warlord Death of Avarice. As the machine died it brought down the Shadow's Heir, a Legio Vulturum Reaver.
No longer embroiled with the Legio Crucius, the Legio Vulturum marched west upon the southern continent, scattering the Legio Osedax before them as fresh reinforcements arrived from orbit. Across the Sea of Reclamation, it fell to Legio Magna to pursue the fleeing Warmongers. To this end, the Flaming Skulls, supported by companies of tanks and the Knights of House Oroborn, descended upon the forge city of Prosperity, sweeping aside any in their way. At Prosperity the remnants of the Legio Crucius alongside three maniples of the Legio Honorum and surviving House Vornherr Knights gathered. Despite Prosperity's formidable defences the Legio Magna made a head-on assault with nearly 50 Titans. Though heavily outnumbered the loyalists managed to inflict losses on the traitors by luring them into minefields with burrowing smart mines which emerged from the earth to attack the foe. The traitors were able to use Scrapcode to take control of some of the mines, unleashing them upon the loyalists. It was in this chaos that the traitor force slammed into the loyalist line. A brutal melee erupted in the centre while at the flanks the Loyalists moved to put distance between them and the corrupted mines still bursting from the surface. In their haste, those of Legio Honorum upon the left flank moved too far afield, opening the way for three Warlords of Legio Magna to break through and besiege the walls of Prosperity itself, packs of Warhounds following in their wake. Fist of Fire, Perdition’s Emissary, and Invocatio Ignis tore through the outer wall, weathering the fire turned upon them by those who had detected the breakthrough. Within moments an entire section of the wall had fallen, the faster elements of the Traitor force cresting the breach and entering the city. As panicked cries filled the vox, those Loyalist Titans refocused their efforts on sealing the breach, relieving the pressure on the foes before them. As one, Legio Magna surged forwards, punishing their enemy for diverting their attention.
As any semblance of coherency within both forces faded, the trio of Legio Magna Warlords marched across the breach, scouring the defenders before them. As the Warlords pushed into the city, only a handful of Warhounds stood against them, outweighed and outmatched by the Traitor forces. However three Legio Honorum Warbringer Nemesis Titans still managed to bring down the commanding traitor Warlord Fist of Fire. The Loyalists then turned their wrath upon the Reavers atop the breach. Concealed by the walls of Prosperity, the Warbringer Nemesis Titans exacted a terrible toll upon the Legio Magna, weapons fire guided by Warhounds ranging ahead of them.
As their fortune turned, the Flaming Skulls withdrew from battle, several of their number falling in retreat. Of the surviving Loyalists, nine had fallen, five fewer than that of Legio Magna. As both sides regrouped, the Traitors plotted their next moves. Fabricator-Locum Omnicron responded by having his Chaos Cults within the city rise up and enact foul rituals that summoned rivers of blood which sickened all that touched it. At the apex of madness, as the city screamed its woes to the heavens, a great otherworldly howl rent the night, torn from the throat of a creature ancient and terrible. In an instant, every machine across Prosperity fell silent. Prosperity was abandoned to its fate.
The city of Prosperity was not the sole victim of the Traitors’ wrath. Upon the southern continent the Gore Crows picked apart the Loyalist forces; not for them the expedient bloodshed practiced by Legio Magna. In the weeks following the fall of Salvation Isthmus, Scrindus Tepfra divided his force into three, each tasked with establishing dominion over a section of the southern continent. As the Gore Crows satiated themselves with the destruction of all resistance, Princeps Magnus Tsaue of Legio Mortis gathered his Titan Legion and the Knights of House Morbidia together. Fed information by pro-traitor cells, Tsaue enacted a rapid assault upon the forge-fane of Causcaut. In a single night the traitors were able to capture the position and then moved their attention to the city of Endeavour, seat of the Hierophant Technis.
In a coordinated thrust, Tsaue and his forces marched directly upon Endeavour, his allies in Legio Vulturum withdrawing from their torment of Loyalist forces to reinforce the Legio Mortis assault. In a single morning they swept aside the small guard of Legio Osedax Titans left in defence of the city, forcing their way through its walls. Unprepared for the sudden ferocity of the Traitor assault, the Loyalist forces proved unable to muster a counter-attack to prevent the Traitors from reinforcing their position, and the Titans of Legio Vulturum encircled the city, closing the noose around Hierophant Technis. Technis was captured and her broken form paraded by the traitors in the fallen city.
It was then that nearly 200 Knights of House Taranis and Zavora launched an assault upon Endeavour. The Legio Osedax were shamed by the suicidal charge of their Knight allies and Princeps Nuvas launched an attack in support. In the battle that followed only 49 of the 189 Knights reached the enemy walls. The Knight Castigator Gladius Ignium of House Taranis managed to reach the enemy and fell the Reaver Titan Mors Foedus. Four enemy titans were claimed by the Knights and the rest were trapped between their tormentors within the city and the advancing Loyalist Titans without, unable to turn upon one without exposing themselves to the other. In response, Tsaue ordered his forces to close ranks, each maniple merging void shields and isolating themselves, the Titans amongst them facing all directions as each guarded the flanks of those closest to them. Such a tactic blunted the efforts of Houses Taranis and Zavora to assail their foes but ensured the weight of fire unleashed upon the advancing Legio Osedax was lessened. For Tsaue, this manoeuvre was intended to buy time for those of House Morbidia within Endeavour to answer the calls for aid and engage the decimated Loyalist Knights, leaving Legio Osedax easy prey. This change of tactic proved to be the breakthrough that Nuvas needed and the Reavers Titans Fated Warrior and Lost Son launched a storm of missiles with unique payloads. Tsaue turned their guns upon the advancing Reavers, the Warlord’s volcano cannon felling Lost Son. Roaring in triumph, the machine spirit’s lust to kill overcame Tsaue and it was too late that the Princeps noticed his reactor flaring red. In the moments before his death, Tsaue realized Legio Osedax intended a fate other than mere death. Atop the carapace of Fated Warrior a final barrage of missiles was unleashed, the warheads striking the shields of Vita Messorem. Though they failed to breach the formidable barrier, that was not their intent. Within the Titan the reactor failed, its containment breaching as a wave of heat engulfed the Warlord. The Vita Messorem was torn apart from within, the subsequent explosion consuming the Titans of Legio Mortis arrayed around it. When the nova faded the surrounding city blocks were nothing but a molten crater, seven Death’s Heads Titans left as smoking ruins within.
The sudden loss of nearly all of the Legio Mortis Titans broke the traitor morale. Legio Vulturum ordered a full retreat, abandoning their allies. In a final act of treachery the Gore Crows turned their guns upon those of the Legio Mortis still standing, attempting to halt their retreat. As the Traitors tore each other apart the Cockatrices seized the walls of Prosperity, pushing through the city to link up with the beleaguered defenders. No longer threatened by the might of the Traitor Titan Legions, the remnants of the Loyalist defenders emerged from the shadows, the Hierophant Technis urging her forces to reclaim the city whatever the cost. To this end the war vaults of Ryza opened and forbidden technologies were unleashed. The previously unknown House Sidus emerged upon the battlefield and together with House Taranis, House Zavora, and the Legio Osedax were able to drive the traitors from their midst. With Endeavour secured, the loyalists under Heldentun summoned a sect of Tech-Priests known as the Cog Erudition to bind ancient technology to the remaining loyalist Titans. The exact nature of this equipment is unknown save the reports that traitor Titans were torn asunder with single blows and cast into the realm of the Immaterium. Armed with these weapons, the loyalists moved to cast the traitors from their world. Resistance proved light upon the southern continent as the assembled Loyalist force, led by Legio Osedax and House Sidus, marched across captured territory. Scattered battalions of corrupted Skitarii and battered tank companies fought in vain against the advancing Loyalist line. Having suffered greatly at the hands of betrayal, Heldentun slowed her pursuit, seeking new information before pushing too far.
To this end, House Sidus was sent to recapture Mount Causcaut and the forge-fane atop it. In this they were opposed by House Morbidia, the Traitors wholly unprepared for the fury unleashed by the newly emergent Knight House. On the flanks of the mountain the two Houses fought upon the slopes. In mere hours, House Sidus and its superior firepower were able to break the back of House Morbidia. The traitors began withdrawing towards Conveyance Terminus Nine-Omega, burning all as they retreated. Omnicron knew he could no longer seize the world intact, but feared Horus' wrath should he fail. He moved to instead cripple Ryza's infrastructure before withdrawing. The traitor forces gathered at the Spaceport and began to board their transports. The final battle for the spaceport saw the Traitors still garrisoned within abandoned by their allies. Their numbers included 11 Legio Vulturum and 14 Legio Magna Titans. The Traitor Titans vowed to fight to the death as both sides deployed their infantry. 60 Loyalist Titans engaged the Traitors. The battle that followed was ferocious, raging for 13 hours. The Loyalist infantry withdrew after the sixth to preserve their strength and avoid becoming victims of the weapons fire of their own Titan allies. The last Titan to fall in the battle was the Sanguiem Luna, and though the loyalists stood victorious, their victory was Pyrrhic at best. In the weeks that followed fires raged across Ryza as the Traitors unleashed an orbital bombardment before departing. Only a fifth of Ryza's forge's remained in the aftermath of the assault.
Decades later when Ryza Secundus was rebuilt the names of the 12 Knights of House Vornherr that defended it were inscribed upon its hull in text 20 meters high.