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.
