Astartes launch major assault on New Cerberex

In the recent history of the Zadoc Subsector, the xenos empire of the Tau proved a tenacious and calculating foe. Entrenched within the dense stellar shoals of the Mabb Nebula, their forces maintained defensive supremacy across multiple theatres, most notably upon the contested worlds of Hylas and New Cerberex. There, Imperial offensives faltered, grinding into prolonged stalemate as supply lines strained and attrition mounted.

Upon Hylas, Lord General Van Dorn marshalled his regiments for a renewed assault, seeking to break the deadlock through overwhelming force. Yet while the Astra Militarum prepared for war in the open, the Adeptus Astartes enacted a more decisive stratagem upon New Cerberex.

The Fall of New Grasx

By 0204.026.M42, the arrival of the Sky Lords Chapter bolstered Imperial strength, and a coordinated strike was authorised. The Dark Angels, ever secretive in purpose, led the assault upon the city of New Grasx—an urban stronghold believed to be lightly defended.

Initial reports confirmed minimal resistance. The Astartes advanced with disciplined precision, securing districts with alarming ease. Yet this absence of opposition was no boon—it was design.

New Grasx had been abandoned as bait.

The true objective of the campaign soon became apparent: the encirclement and subsequent siege of New Feducia, a heavily fortified Tau bastion of strategic and logistical significance. The Dark Angels’ advance had drawn them into position—but also into peril.

From hidden vectors emerged the Kel Sandros Aeldari, xenos allies of the Tau. Striking with speed and lethal grace, they sought to disrupt the encroaching Astartes before the noose around New Feducia could tighten.

What followed was a brutal clash of doctrines—Aeldari finesse against the implacable might of the Adeptus Astartes.

The Dark Angels responded with characteristic ruthlessness. Terminator squads were deployed into the heart of the engagement, their tactical dreadnought armour rendering them all but impervious to the Aeldari’s initial volleys. The confined urban terrain negated much of the Eldar’s mobility, forcing them into a grinding confrontation they could not sustain.

It was, by all accounts, a slaughter.

Yet the Aeldari did not break entirely. In a final act of defiance, a lone Fire Prism grav-tank executed a daring rearguard action. Plunging through withering bolter and plasma fire, it struck directly into an advancing Space Marine squad, scattering their formation and buying precious moments.

That sacrifice allowed the remaining Aeldari forces to withdraw into their webway portal, vanishing from realspace before annihilation could be completed.

By 0404.026.M42, New Grasx was firmly in Imperial hands.

The Assault on Suter

While the Dark Angels secured their foothold, the Sky Lords enacted a rapid strike operation upon the world of Suter—an engagement defined by speed, precision, and calculated risk.

Critical to the operation were a number of sacred Adeptus Mechanicus devices deployed from orbit. These artefacts—designed to disrupt and override Tau automated defence networks—had been scattered across hostile territory, their landing zones compromised by enemy proximity.

The Sky Lords did not hesitate.

Executing high-velocity insertion assaults, they struck deep behind Tau lines, engaging in swift and violent skirmishes to reclaim the Mechanicus assets before the enemy could react. Despite taking notable casualties in these engagements, the Chapter’s relentless tempo denied the Tau any opportunity to consolidate or counterattack effectively.

Within hours, the devices were secured and activated.

The effect was immediate and catastrophic for the Tau defenders. Automated drone networks faltered, defensive emplacements were silenced, and coordinated resistance collapsed into fragmentation.

With their technological advantage nullified, Tau forces on Suter were unable to maintain cohesion against the advancing Astartes.

By 0504.026.M42, Suter had fallen.

The Encirclement of New Feducia

In the wake of these twin victories, the strategic situation shifted decisively in favour of the Imperium.

With New Grasx secured and Suter neutralised, Astartes forces converged upon New Feducia, sealing its approaches and severing its supply routes. The Tau stronghold, once a lynchpin of their control within the Zadoc Subsector, now stood isolated—encircled by the Emperor’s finest.

Thus began the Siege of New Feducia, a campaign that would determine the fate of the Mabb Nebula and the wider war for the subsector.

Hadron Expanse 03.026M42

By 03.026.M42, the Tyranid threat within the Hadron Expanse had escalated to catastrophic levels. What had once been a creeping infestation had now become a full-scale planetary consumption effort, as elements of Hive Fleet Poseidon expanded their grip across multiple warzones simultaneously.

The Fall of the World Eaters on Haven

On the war-torn world of Haven, the Tyranids encountered a substantial warband of the World Eaters, whose presence had previously complicated both Imperial and Ork operations. The resulting engagement was savage and unrelenting, even by the brutal standards of the XII Legion.

Yet for all their fury, the World Eaters were no match for the sheer scale and adaptability of the swarm. The Tyranids annihilated the warband entirely, leaving no survivors and conclusively establishing their presence on Haven as a permanent infestation. From that point onward, the world ceased to be merely contested—it became a feeding ground.

Crisis on Helos Majoris

Simultaneously, the situation on Helos Majoris deteriorated rapidly. Tyranid forces launched a major offensive, breaching deep into Imperial defensive lines that had already been weakened by months of attrition.

The Astra Militarum bore the brunt of the assault. Entire formations were destroyed in the fighting, with one regiment reportedly reduced to a single surviving Rough Rider, an anecdote that spread rapidly through Imperial channels as both a symbol of heroism and of impending disaster.

Despite inflicting heavy casualties on the Tyranid horde, the Imperium found little comfort in the toll exacted. The swarm absorbed the losses without hesitation, its numbers seemingly inexhaustible.

By mid 03.026.M42, Imperial forces had been driven back across multiple defensive zones, and the strategic situation on Helos Majoris was described in official reports as critical.

The Intervention of the Dark Angels

Relief came only with the arrival of the Dark Angels, who were redeployed to the front lines in a desperate attempt to stabilise the collapsing defence. In an exceptionally bloody series of engagements, the Chapter brought its formidable discipline and firepower to bear against the Tyranid advance.

The fighting reached its climax in the closing days of the month. In a hard-fought defensive action, the Dark Angels succeeded in halting the Tyranid offensive, inflicting enough damage to force the swarm into temporary withdrawal and stabilising the Imperial line.

Strategic Collapse Looming

Yet even this victory could not mask the grim reality:

• By the end of 03.026.M42, the Tyranids controlled approximately half of Helos Majoris.

• Hive Fleet elements had begun appearing within the Hecate Gap, threatening Imperial positions from the rear.

• Supply lines were under increasing pressure, and Imperial forces were stretched to breaking point.

The question of strategy now came to the forefront. Increasingly, senior Imperial officers and sector authorities began to question General Maximus’s refusal to withdraw from the Rifts of Hecate. What had once been a bold forward strategy was now being seen by many as a potential overextension—one that risked encirclement and total collapse.

By the end of 03.026.M42, the Imperium still held Helos Majoris—but only just. The Tyranids had not been defeated. They had merely been delayed. And in the Hadron Expanse, delay was rarely enough.

Imperium grind to victory on Mordecai Prinaris

In the opening months of 026.M42, the war for Mordecai Primaris entered a decisive phase. The grinding attrition that had defined the previous year began to shift in favour of the Imperium, as General Kutuzov leveraged not only numerical superiority, but the direct intervention of some of the Emperor’s most elite warriors.

The Grey Knights and the Fall of the World Eaters

The first major turning point came with the deployment of the Grey Knights into the northern hive sprawl. Tasked with eliminating particularly dangerous Chaos elements, they engaged a warband of the World Eaters entrenched within the shattered hab-zones.

The battle was ferocious even by Astartes standards. At its height, a towering Khorne Lord of Skulls carved a bloody path through the Grey Knights’ ranks, annihilating multiple squads and threatening to break the Imperial assault. Yet the daemon engine’s rampage was ultimately halted by a determined counterattack from a formation of Grey Knight Paladins, who brought it down in a brutal close-range engagement.

With their war engine destroyed, the World Eaters force collapsed, their berserk fury insufficient against the disciplined might of the Emperor’s daemon-hunters.

Custodian Intervention

Following this victory, the Adeptus Custodes were committed to further offensives within the hive sprawl. Their engagement with a Chaos Space Marine force proved no less costly. The fighting devolved into savage, close-quarters combat within the ruins, where even the golden warriors of Terra were forced to pay in blood.

Despite the intensity of the resistance, the Custodes prevailed, breaking the Chaos line and forcing yet another withdrawal. Each such victory tightened the noose around the remaining Chaos strongholds.

The Fracturing of Chaos

As defeats mounted, the already tenuous alliance between the various Chaos factions began to unravel. Rivalries, long suppressed by necessity, erupted into open conflict.

The most dramatic rupture came from the Night Lords, who turned against their supposed allies, denouncing their leadership as weak and incompetent. What followed was a series of brutal internecine clashes:

• Night Lords forces struck first against the Death Guard, defeating them in a vicious engagement.

• Emboldened, they then turned on the World Eaters, overcoming them in another savage confrontation.

These internal conflicts further weakened Chaos resistance across Mordecai Primaris, accelerating Imperial gains.

Strategic Concerns

Yet the situation was not without its dangers.

While the collapse of Chaos unity benefited the Imperium in the short term, Kutuzov and his high command recognised a growing threat. The Night Lords, through their victories, risked emerging as the dominant Chaos force on the world—one capable of imposing order where previously there had been only disunity.

Such an outcome would transform a fractured enemy into a more coordinated and dangerous opponent.

By early 026.M42, the Imperium held the initiative on Mordecai Primaris. The forces of Chaos were in retreat, divided, and weakened.

But as history had often shown, the servants of the Dark Gods were never more dangerous than when forged anew from the fires of their own destruction.

Excerpt from the Caitlen Station Conflict Ledger, Aleph Sector Strategic Archive

Recorded: Mid 026.M42

As 026.M42 progressed, the war within the sprawling void-ruins of Caitlen Station showed no sign of resolution. The installation remained a fractured battlefield of shifting front lines, where gains were measured in corridors and docking bays, and no single faction could maintain dominance for long.

Chaos Advances and Ork Resistance

Among the most aggressive actors were the Nemesis Claws, a Night Lords warband devoted to terror and opportunistic warfare. Through a series of calculated strikes, they succeeded in seizing additional territory from entrenched Ork warbands, carving out a temporary foothold in one of the station’s mid-tier industrial sectors.

Yet, as was increasingly common on Caitlen Station, no victory went uncontested.

The Four-Way Engagement

In what would become one of the most chaotic engagements of the campaign, a four-way battle erupted in the contested sector. Imperial Deathwatch kill-teams, Ork forces, the Nemesis Claws, and a small Votann Hearthkyn squad—seeking to exploit the instability for Federacy interests—collided in a brutal and confused firefight.

The engagement rapidly devolved into close-quarters carnage. The Orks surged forward with characteristic aggression, the Night Lords struck from shadowed flanks, and the Votann attempted to hold disciplined firing lines amidst the chaos. Into this maelstrom, the Deathwatch brought their specialist training and xenos-hunting expertise to bear.

Despite being outnumbered and surrounded by multiple hostile forces, the Deathwatch systematically eliminated their enemies. Through disciplined fire, coordinated strikes, and superior battlefield awareness, they emerged as the victors of the engagement, securing the sector in the aftermath.

Tyranid Incursion

The victory, however, proved fleeting.

Within hours, bio-signatures began to spike across the area. Elements of Hive Fleet Poseidon, already deeply embedded within Caitlen Station’s lower decks, surged upward in overwhelming numbers. The Tyranids fell upon the weakened Deathwatch force with relentless ferocity.

Even the elite Astartes of the Deathwatch could not withstand the sheer mass of the swarm. The position was overrun, and the sector fell swiftly into Tyranid control.

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Strategic Assessment

By mid 026.M42, Caitlen Station remained firmly contested:

• Chaos warbands continued to expand opportunistically but could not hold ground against sustained opposition.

• Ork forces remained numerous and disruptive but lacked cohesion.

• The Imperium achieved tactical successes but failed to convert them into lasting control.

• The Tau–Federacy alliance operated cautiously, seeking advantage but suffering from limited presence.

• The Tyranids, however, continued to grow in strength with minimal strategic cost.

Of all the factions present, it was the Tyranid infestation that caused the greatest concern. Unlike their rivals, the swarm did not require supply lines, coordination, or strategic restraint—only biomass.

No force appeared close to securing Caitlen Station.

But increasingly, it seemed that if any power would ultimately claim it, it would not be by conquest — but by consumption.

Excerpt from the Zadoc Subsector War Annals, Segmentum Obscurus Command Archive Recorded: Early 026.M42

The opening months of 026.M42 brought no respite to the embattled Zadoc Subsector. Though large-scale offensives had temporarily abated, the region remained far from quiet. Beneath the surface, a shadow war of raids, sabotage, and probing assaults continued unabated, as each faction sought advantage while preparing for the next major phase of the conflict.

Imperial Consolidation

At the centre of Imperial operations, General Van Dorn spent the preceding six months consolidating his gains. Reinforcements had been steadily deployed, supply lines reinforced, and new staging grounds established across contested worlds such as New Cerberex and Hylas. Though no major offensive had yet been launched, it was clear to observers that the Imperium was preparing for a decisive campaign.

Chaos Raids from Fort Sparcos

While the Imperium gathered strength, the forces of Chaos—particularly those entrenched at Fort Sparcos—remained highly active. Two major raids launched from the fortress demonstrated both the reach and volatility of the traitor warbands.

The first, carried out by the Thousand Sons in concert with large numbers of Tzaangor war-beasts, struck the T’au outpost on Tyndareous. The assault came without warning, emerging from warp-distorted vectors that bypassed conventional detection. The T’au defenders were caught completely unprepared. The resulting engagement was brief and devastating: the garrison was massacred, supply depots were obliterated, and critical infrastructure was left in ruins. By all accounts, it was a highly successful raid, dealing a significant logistical blow to the T’au presence in the region.

The second raid, however, proved far less effective.

A strike force of Night Lords attempted to infiltrate the Ork-held world of Bothorion, likely intending to destabilise the greenskin presence or carve out a foothold amidst the chaos. Yet the VIII Legion’s reliance on terror and stealth faltered against the crude but brutally effective vigilance of the Orks. The greenskins detected the infiltration earlier than anticipated, and what followed was not a calculated strike—but a slaughter.

The Night Lords were overwhelmed by sheer Ork aggression, their tactics rendered ineffective in the face of relentless close-quarters combat. Only a handful of the traitor Astartes escaped the disaster, fleeing into the void with their numbers shattered.

By early 026.M42, the situation in the Zadoc Subsector remained finely balanced. The Imperium prepared for a renewed push, the T’au struggled to recover from sustained disruption, and Chaos continued to lash out unpredictably from its strongholds.

The war had not paused—it had merely shifted into the shadows, where each strike, each raid, and each failure would shape the battles yet to come.

Caitlen station 12.025M42

Excerpt from the Caitlen Station War Record, Aleph Sector Archive

Recorded: 12.025.M42

In the final month of 025.M42, violence continued unabated across the vast, labyrinthine corridors, docks, and sub-structures of Caitlen Station. The shattered megastructure, already fractured by years of neglect and infestation, had become a shifting mosaic of short-lived victories and brutal reversals, where no faction could hold territory for long.

Skirmishes in the Inner Decks

Imperial Astartes strike elements—operating without heavy support and cut off from sustained reinforcement—launched a successful purge against a Death Guard patrol in the station’s inner maintenance levels. The engagement was swift and brutal, with the Plague Marines annihilated in close-quarters combat and their corrupted war-gear destroyed.

For a brief time, the Space Marines secured a series of strategic junctions and access corridors, marking one of the few clear Imperial victories within the station’s interior zones. The victory, however, proved fleeting.

Within days, a roving Ork warband surged through the same sector. Overwhelming the depleted Astartes force through sheer numbers and ferocity, the greenskins drove the Space Marines from their newly claimed objectives. The Orks seized the area in a storm of violence, looting equipment, fortifying scrap barricades, and transforming the corridors into crude strongpoints.

The Federacy Consolidates

Elsewhere on Caitlen Station, the Tau–Federal Alliance adopted a markedly different posture. Rather than committing to direct confrontation, Federacy forces—primarily Votann Hearthkyn elements—conducted organised training exercises within their secured zones. These drills focused on void-combat manoeuvres, corridor clearing, and rapid redeployment tactics, suggesting long-term strategic intent rather than short-term opportunism.

Imperial intelligence interpreted this as a sign that the Federacy was preparing for sustained operations on the station, rather than mere raiding or looting.

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By the end of 12.025.M42, Caitlen Station remained a fragmented and contested battlefield. Control shifted constantly between factions, with victories measured in corridors and junction nodes rather than sectors or decks. No single power dominated the installation, and every gain was temporary.

The station had become not a prize to be seized—but a permanent warzone, where conflict itself was the only constant.

Tyranids breach Imperial defences

Excerpt from the Chronicles of the Rifts of Hecate, Segmentum Tempestus Archives

Late 025.M42

In the closing months of 025.M42, the Tyranid menace surged once more in intensity, marking a new and dangerous phase in the war for the Hadron Expanse. Confirmed elements of Hive Fleet Poseidon were detected within the Hecate Gap itself, signalling that the extragalactic invasion had breached what many Imperial strategists had believed to be a natural strategic barrier.

The Fall of the Plague Gambit on Haven

On Haven, the Death Guard had established a presence with a singular purpose: to unleash warp-tainted plagues in the hope of both halting the Tyranid advance and disrupting Imperial and Ork operations in the region. True to the nature of the XIV Legion and their patron god, the campaign was as much ritualistic as strategic, driven by Nurgle’s creed as much as by military logic. Yet the gambit failed.

Hive Fleet Poseidon proved utterly resistant to the latest pathogen unleashed by the Plague Marines. The Tyranids adapted with terrifying speed, their bioforms showing no measurable degradation. Despite a stubborn and disciplined defence, the Death Guard were eventually overwhelmed and forced into withdrawal. In their wake, the Tyranids established a new infestation zone on Haven, marking the world as another node in the ever-expanding Tyranid biosphere.

The Breaking Point at Helos Majoris

At Helos Majoris, the situation grew even more dire. For months, General Maximus had defied strategic logic and repeated counsel, holding the world through sheer will, attrition warfare, and the sacrifice of Imperial manpower. Again and again, his forces had repelled Tyranid landings, preserving the planet as the central operational hub of the Rifts of Hecate Crusade. But the cost was becoming unsustainable.

By the final days of 025.M42, the pressure from Hive Fleet Poseidon had become relentless. Imperial formations were exhausted, depleted, and stretched thin across multiple defensive zones. In a rare and desperate escalation, the Adeptus Custodes were deployed to Helos Majoris—an unmistakable sign of the gravity of the situation.

The golden warriors fought with legendary ferocity, cutting down vast numbers of bioforms and holding key landing zones far longer than any conventional force could have managed. Yet even their intervention proved insufficient.

For the first time, Hive Fleet Poseidon successfully established a permanent foothold on Helos Majoris.

This moment marked a strategic turning point. The Tyranids were no longer merely assaulting the world—they were rooting into it. The primary base of operations for Maximus’s entire Rifts of Hecate campaign now stood under direct existential threat.

Strategic Implications

By the end of 025.M42, the situation was clear:

• The Hecate Gap was no longer secure.

• The Tyranids were immune to Chaos plagues and increasingly resistant to all forms of conventional containment.

• Helos Majoris, once the anchor of Imperial resistance in the Rifts, had become a frontline world.

• General Maximus’s refusal to withdraw had transformed a strategic stronghold into a potential Tyranid beachhead.

What had once been a campaign of containment had become a fight for survival.

The Rifts of Hecate were no longer a buffer zone.

They were becoming a Tyranid domain.