Vanitor is an Imperial Frontier World and wilderness world that is the fourth planet of the Konor System in the Realm of Ultramar. Vanitor is a harsh and windswept world that houses the Konor System's astropathic relay. Without this key communications outpost, the system would be left completely isolated from the wider Imperium. The world came under sustained attack by the Forces of Chaos in service to Nurgle during the Plague Wars of the early 42nd Millennium.
History
The Plague Wars
Having gathered significant momentum with their early victories on the outskirts of the Konor System during the Plague Wars, the armies of Chaos spread out across the region like poison seeping into the blood stream of the Imperium.
When the Plague Wars began, Ultramar burned. The putrid warbands of the Death Guard, led by the Daemon Primarch Mortarion, launched a furious assault upon the Ultramarines' stellar empire. This eruption of all-out war threatened to drown the stars themselves in bloodshed and terror. Legions of Heretic Astartes and Chaos-spawned monstrosities have already rampaged across world after world, spreading the malignant corruption of the Dark Gods in their wake. Yet all hope is not lost. The return of the Primarch Roboute Guilliman to the region with the end of the Indomitus Crusade has stalled the seemingly unstoppable momentum of the Chaos advance. In a series of bloody battles, the armies of the Imperium -- reinforced with mighty Primaris Space Marines -- have reclaimed many worlds thought lost, forcing their hated foes to retreat and regroup.
The worshippers of Chaos sought to regain their advantage by smashing a path through the Imperial battle line to Macragge, homeworld of the Ultramarines. Had they succeeded, the greatest Imperial stronghold in the sector would have been gravely threatened, and Guilliman's forces cut-off and surrounded. To achieve this end, the Forces of Chaos had to conquer the well-located Konor System. Powered by the industrial might of the Forge World of Konor, this centre of produce and production feeds the Imperial war machine with vital shipments of munitions and machinery. Populous and prosperous, with a large and well-equipped defence force, the Konor System embodies the glorious dream that is Ultramar. Crucially, it also guarded one of the few stable Warp transit routes to the Macragge System. If the Chaos advance was not halted, Konor would have fallen, and a path to the heartland of Ultramar would be laid bare to the forces of the Ruinous Powers.
Yet the warriors of the Adeptus Astartes had no intention of ceding their rightful domain without a fight. The Ultramarines stood against the Chaos onslaught with nobility and courage, smiting the foe with Bolter and blade. And they are not alone. The military sledgehammer of the Astra Militarum rumbled into action, an armoured fist of devastating tank columns and endless regiments of soldiers that ground all before it into ashes and dust. Scattered Space Marine Chapters rushed fresh reinforcements to the war zone, seeking to aid their embattled kin. Enigmatic Tech-priests of the Adeptus Mechanicus sent forth their legions of steel, and mighty Imperial Knights bestrode the slaughter like ancient gods of war.
Every single warrior -- every Bolter round and bomb -- was vital, for the Chaos host sweeping across the Konor System was vast beyond imagining. Warriors of the Death Guard marched implacably forward, enemy fire spattering harmlessly from their rusted, ancient Power Armour and pallid, twisted flesh. In return, they unleashed bombardments of noxious toxins and flesh-melting plagues. Daemonic legions surge alongside the Chaos advance, exulting in the chance to wreak torment across the material realm. Warbands of Heretic Astartes, millions upon millions of depraved mortal Chaos Cultists, and a thousand other horrors converged upon Konor, drawn to its aura of agony and death like sharks to blood.
Circling this firestorm of destruction were predatory xenos races, ever seeking to further their own mysterious ends. Orks surged into the war in their millions, delighting in the spreading carnage. Craftworld Aeldari and Drukhari circled from afar, offering their services as mercenaries to both sides or launching raids to fulfill some unknowable agenda. Tyranid and T'au forces spilled in from the Eastern Fringe, capitalising on or drawn by the escalating conflict, while even the Necrons sent undying invasion forces to exploit the infighting of the younger races and expand their ancient empires.
No part of the Konor System was left unscarred by the war. If the Heretic Astartes' plans came to fruition, the system's own worlds would have been weaponised and turned against Ultramar. The Forces of Chaos intended to force open a route to Macragge, and that shining light of the Imperium would face obliteration.
The Vanitor Campaign
The Konorian Astropathic Relay, situated upon the wilderness world of Vanitor and guarded by a vast fortress basilica, once linked the Konor System's Imperial defence force to the greater war effort across Ultramar. It was one of the first targets overwhelmed in the initial blitz of the Chaos invasion, for severing this line of communication left the Konor System shrouded in darkness and confusion. Despite a brave stand, the Departmento Munitorum forces responsible for maintaining and defending the facility were encircled and slaughtered. The relay's astropathic choir were ritually bound and excruciated by Chaos Sorcerers, and the sheer agony of their torment -- amplified by the unfortunate beings' raw psychic power == became a shining beacon to the ravenous monstrosities of the Warp.
This piercing psychic scream soon came to the attention of the Grey Knights, who had swiftly identified the growing conflict in Ultramar as a potential lodestone that would draw entities from the roiling depths of the immaterium into realspace. The grim brotherhood of Daemon-hunters knew that to allow this beacon to continue to broadcast its vile signal would ultimately invite the horror of a sector-wide daemonic incursion. Gathering allies to their side, the Grey Knights assembled several strike forces and fell upon the corrupted defenders of Vanitor with merciless brutality, hacking apart Chaos-spawned horrors and their wretched masters. Yet even the Grey Knights could not accurately grasp the nightmare that was spreading across this windswept wilderness world.
Upon the great plains, vast warp breaches vomit the rancid deluge of the empyrean into reality. Amidst the soaring Tremantaen Mountains, Heretic Astartes and their foul minions have dug in like ticks, creating a circle of rockcrete redoubts around the relay, which rests atop the highest peak. Blizzards of frozen blood and transmutative hurricanes whip through these mountain passes, birthing new flyblown horrors or flaying the flesh from those foolish enough to brave the open air. At the Konorian Relay itself, Chaos forces defend their tortured wards with savage determination, unleashing blistering cascades of gunfire and artillery upon those who look to breach the basilica walls. If the Imperials cannot break through this formidable barrier, the agony of the tortured astropaths will only flare brighter, drowning Vanitor in the surging tides of the warp. Surely the damnation of the entire Konor System will swiftly follow.