"This foul rock has haunted our space for far too long, and by my hammer Doombringer we will shatter it and empty the vermin inside once and for all! For Russ! For the Eternal Vigil!"
- —Captain Haakon Draugrsbane of the Space Wolves
In a region of space known for the numerous derelicts floating between the stars, it is the dark form that blots out local suns, causing civilisations to fall into barbarism or new religions to sprout like weeds.
Under hundreds of names it is the blight on the void, the bane of Warp-travel, and the ruination of innumerable ships from its catastrophically sudden appearances. In their secret language, Navigators call it "The Doom that Awaits." Deathwatch Librarians officially record it as "Warp Artefact Aleph-Omicron-002."
For most in the Jericho Reach, and particularly in the Achilus Crusade's Orpheus Salient, it is known as the Mortis Thule -- Death From Beyond the Horizon -- the largest space hulk known to exist in the region, and very possibly the most dangerous.
Space hulks are not an uncommon occurrence in areas of space with advanced interstellar travel. These massive conglomerations of discarded voidship hulls and space debris are legendary across the galaxy, famous both for the lurking dangers they host as well as the possible treasures hidden inside.
Though each is unique, the Mortis Thule stands out not only for its enormous size but also for its long history in the Reach, dating back to before the arrival of the Imperial expeditionary fleets of the Great Crusade. Most hulks either fall apart given time (or sufficient massed firepower), or disappear back into the Warp never to be seen again.
The Mortis Thule seems older than many such space hulks encountered before, however; its curious longevity and increasing mass are possibly tied to that other mysterious artefact of the Reach, the Jericho-Maw Warp Gate.
The sighting of a space hulk is a significant one for any void travellers, sure to be logged and studied for possible plunder and hazards to Warp travel. Thus it is not unusual for fairly detailed records to exist of such a vessel, especially one as exceptional as the Mortis Thule.
The Inquisition and the Deathwatch are believed to have the most numerous and complete records extant, but even these contain much apocryphal and contradictory information. Such is the nature of the hulk that even the most factual of sightings become spun into legend after only a few short tellings.
The earliest suggestions of the hulk's appearance were uncovered on Shinno, an otherwise unremarkable planet rimward of the Slinnar Drift, its native civilisation routinely eradicated during the Great Crusade.
Xenos-archaeologists of the 427th Expeditionary Fleet uncovered what appeared to be ancient pictograms dating roughly twelve thousand Terran years before the Great Crusade, indicating a dark shadow in the sky and tales of earthquakes, meteor showers, and invasions of terrible, unnatural beasts.
There are few other records until the coming of the Great Crusade itself to the Jericho Sector, but its arrival and the subsequent increase in Warp traffic seemed to trigger further contacts. Throughout the millennia before the onset of the sector's Age of Shadow, the Mortis Thule appeared sporadically across the region and was the subject of many hundreds of boarding actions.
It was one such attempt to conquer the Mortis Thule on the empty shoals near Phonos that gave rise to its common name. In the 33rd Millennium there was a joint landing action of a consolidated massive attack force led by Adeptus Mechanicus Archmagos Mitsfian Delphos and Rogue Trader Hyrus Tarrant.
After initial successes against hosts of aliens in the main landing zones and breaches into several cargo holds, fighting began anew but seemed to be due to the multiple boarding forces fighting each other. There were few survivors rescued along with some pillaged archeotech treasures, with wild claims of death itself stalking the derelict hulls.
Of Delphos or Tarrant there was no sign, and Tarrant's daughter Minerva Tarrant cursed the Mortis Thule to forever be a distant death to her lineage. True to her word, her fleets soon departed the sector though there are rumours the enormous bounty for information on her father's final disposition still stands for House Tarrant.
The Deathwatch itself leads numerous, though less well-known, actions against the Mortis Thule as well. As is their wont, through the centuries Ork raiders have often established bases on the many voidships contained in the assemblage, using these as springboards for marauding operations.
Deathwatch Kill-teams were called in on occasion when the raids became especially threatening to Imperial systems, but for the most part acted to eradicate the specific menace and (perhaps wisely) did not attempt to infiltrate the rest of the Mortis Thule.
There were also at least 37 recorded incursions at the specific request of the Inquisition, including five to rescue or recover valued Imperial agents trapped on the Mortis Thule for unrevealed reasons and one to destroy an interred vessel broadcasting unfathomable Warp-beacon transmissions to parties unknown.
Not all have been successful; there are multiple shrines in Watch Fortress Erioch to those who never returned from the space hulk, where those of their Chapters may hold private ceremonies in their memory and swear anew their oaths of vengeance.
During the Age of Shadow, the records become less precise; amidst the collapse of the sector, few seemed interested in recording the appearance of even this ominous craft. Those that did investigate it, such as the adepts of Samech before they were lost to tech-heresy, left no history behind of what they found.
As Warp Storms increased and sightings diminished, it seemed that perhaps the Mortis Thule was lost to the Empyrean forever.
The re-emergence of the Imperium through the Jericho-Maw Warp Gate into the Jericho Reach in the late 41st Millennium also saw the return of Mortis Thule as it began to be detected with greater frequency, especially in the Achilus Crusade's Orpheus Salient. This of course could be attributed to the increased number of Imperial vessels and their travel in the Reach.
Some faction-cants in the Adeptus Mechanicus who also study the enigmatic Warp Gate insist that there could be more than coincidence here and strive for greater research on the space hulk's unnaturally growing size. There have certainly been more Deathwatch missions assigned against it in recent years.
On manifold occasions Kill-teams have been sent to mitigate the predations the Mortis Thule brings to a system or Warp travel route, acting to keep pockets of the Orpheus Salient from collapsing.
With the arrival of Hive Fleet Dagon in the Reach, Tyranid infestations on the space hulk have grown and more missions have been sent purely to burn away Tyranid growths that would have become new mycetic spores otherwise.
Some operations have been purely to map out as much data as possible on the hulk's vast interior and the cluster of hulls melded inside, while others have simply been to visit empty space to see if the newest predictions based on history, divinations, and aetheric soundings for the hulk's arrival are accurate.
Several have been logged purely as "Omega Vault Decree" with no other data recorded. Information is power, and the Inquisition and the Deathwatch seem to be very eager to gain as much of both concerning the Mortis Thule for reasons they have not shared with any other Imperial agencies as of yet.
The Dead Hulls
Mortis Thule is quite simply one of the largest artificial objects found in Jericho Reach space, easily outmassing even Bastion-class space stations. Like all space hulks it appears out of the Warp at seemingly random times, ejecting into realspace with a roaring thunder of psychic energies such that Navigators across the region are alerted.
Its violent appearance disgorges a trail of debris, as megatonnes of metal and rock crack away from the harsh arrival. This loss is more than made up for by new additions of void debris and those unfortunate vessels that find themselves melded into the Mortis Thule's conglomerate mass by powerful Warp tidal forces or worse.
From the outside, the Mortis Thule is roughly flattened and ovoid in shape with large jagged spikes of torn rock and broken prows. The surface is pockmarked with craters from impacts and explosions, some so ancient that other bonded hulls obscure their shape. Not only Imperial vessels make up its body, for the ruins of numerous xenos voidships are also littered across the surface and undoubtedly are located inside as well.
Elegant Aeldari wraithbone structures, crude Ork plating, and even fleshy Tyranid bioships can be seen strewn in the synthesis that makes up the space hulk, along with xenos vessels of unknown origin and archeotech ships predating the Imperium. Inside the Mortis Thule are the remains of countless more dead ships, each a story of uncaring fate or grave accident.
Some are nearly intact, caught in sudden eddies while sailing the Empyrean's powerful seas and fused into the space hulk as both emerge into realspace. Others are broken hulls, ships dashed against the rock and sunken deep along with other Warp flotsam.
Many have become connected together through random internal collision or artificial actions. All seem to contain artefacts of such exquisite value that despite the dangers there have been no shortages of those seeking to plunder the Mortis Thule.
The items recovered range from ancient archeotech relics still being deciphered to baneful xenos weapons declared heretical by joint Ordos decrees, as well as present-day devices left behind by failed boarding parties.
The sheer weight of treasures estimated aboard the Mortis Thule are one of the main reasons that the massive joint efforts needed to destroy or break up the space hulk have failed to coalesce long enough to perform the deed. For every one agency or power base that would wish it gone, there are a dozen more eager to plunder its secrets for their own benefit.
Attempts to create a definitive map to guide future explorations have been doomed to failure however; each sighting reveals new arrangements of the melded assemblage with new ships appearing and older ones broken away.
Pulse-mapping transponders buried deep via burrowing torpedoes have proven somewhat useful, but these invariably fail after only solar weeks of operation due to the stray radiation that permeates the Mortis Thule and even through internal sabotage. The latter is certainly a disquieting thought but not one unexpected given the nature of what lives inside.
The space hulk is certainly a dangerous environment due to its shifting construction -- sections break away or settle deeper into the core with each Warp passage or close orbit to a demanding star -- but it is those that still live amidst the dead hulls that make the Mortis Thule a truly terrifyingly place.
Like most space hulks, there are numerous creatures infesting the dark hulls buried in the rock. Some ships still retain furtive power, flickering and undependable as it may be. The Mortis Thule hosts a multitude of species striving to survive in the artificial carcass.
Each new hull added to the Mortis Thule often also brings new occupants, some advanced enough to maintain some semblance of their culture but most descending into barbarism or worse as each Warp immersion leads them forever into deeper darkness.
The most common denizens of the Mortis Thule are that most widespread of Tyranid species, the Genestealer, a presence even greater now that Hive Fleet Dagon has spread its tendrils across the Orpheus Salient. Genestealers are perhaps perfectly suited to existing on space hulks.
They are extraordinarily tough, with reinforced circulatory systems and leathery protective skin; even their weakest surface membranes are able to withstand complete vacuum exposure for extended durations. Their flesh and their genetic material itself is resistant to most mutating or debilitating radiation, and they seem to have no fear of unprotected Warp travel.
They are very long-lived and able to shut down their metabolism for long periods of time when there is no prey to be had. Their agility and multiple clawed limbs allow them to easily manoeuvre in the hazardous ruins of wrecked gangways, collapsed decks, and areas with failed grav-plating.
Their eyes can penetrate total blackness or obscuring smoke, and their senses can detect the smallest twitch or droplet of blood. Unlike most other Tyranid organisms, they are able to operate effectively when unconnected to the Hive Mind that their related Tyranid species need in order to do more than act according to instinctual behaviour.
Add to this their preternatural strength, ferocity in combat, and talons that can rip through even Terminator Armour, and the Genestealer would already be one of the most dominant threats of any space hulk. It is their means of reproduction that changes them from dangerous predator to an extreme threat to the Imperium itself.
Genestealers reproduce through implanting their viral genetic material into a host organism, often when the unwilling host is unconscious or subdued through a psychically-induced hypnotic state. This material corrupts the parent DNA, causing any offspring to be born as an unnatural mixture of the parent and Genestealer species.
The host is mentally and genetically conditioned to care for these twisted progeny, each of which is also able to quickly mature and infect others through the same genetic implantation. Future generations lead to new Genestealers of a nearly pure strain, unrecognizable from the original species but now carrying partial physiological reminders of the host morphology.
In this way the creature extends its influence across populations and has become the bane of the Ordo Xenos; entire planets have been put to the torch to conclusively prevent their spread. In the Mortis Thule, there are numerous Genestealer-controlled hulls and even more overrun by their hideous offspring.
Any Imperial vessels that depart the space hulk and are not willing to submit to extensive examinations of both ship and personnel, have been utterly destroyed by their colleagues lest they possibly spread the infection to others. With the Genestealer there can be no half-measures; even one creature can lead to the downfall of an entire world.
While the presence of such Tyranid creatures in the Mortis Thule is somewhat to be expected, it is the existence of Enslavers on the space hulk that makes it even more hazardous. Most explorers do not encounter them, or at least never return having done so.
Early Deathwatch squads only reported remains of the grotesque organic flesh-arches that serve as their gateways into reality, but fresh ones have been sighted more recently. Each of these portals was once a psyker, but their unguarded minds have allowed these threats to menace not only the Imperium but every living being in the galaxy, as they once did untold millennia ago.
Even the merest threat of an Enslaver outbreak has brought numerous Deathwatch teams to a planet, ready to obliterate their danger. Entire hive cities have been razed rather than leave any possible Warp portals remaining, and forces sent to the Mortis Thule are on a constant vigil to destroy them on sight, no matter what their original mission might entail.
The Mortis Thule contains many nascent psykers though, almost none with the necessary defences to ward off the dominating alien mentalities. It is the presence of the Genestealers which paradoxically provides such a rich feeding ground for this menace from times before Humanity descended from trees.
All Genestealers share a psychic connection known as the Broodmind that allows them to function as an independent brood. This extends to their offspring; indeed Genestealers will actively seek out psykers as hosts to strengthen this link and their own Tyranid psychic powers.
However, these psychically-attuned offspring shine in the Warp as a near-irresistible beacon to the Enslavers who follow the vessel as it dances between the Empyrean and realspace. The Genestealer broods have become themselves prey, as subjugated brethren have turned on their alien parents at the command of their new masters.
Some Genestealers have sought the sanctuary of stasis tubes within heavily reinforced cargo vaults, their still-loyal children sealing the vault from the inside and committing suicide as a desperate measure against Enslaver-dominated forces.
Ferocious battles between the horrific Tyranid predators and the ghastly Enslavers are nightmare tales of legend. The rending claws of the Genestealers rip through hordes of bound puppet-races to reach their enemies' floating bulbous bodies. Tendrils writhe beneath Enslavers over the blood-soaked decks as they command their slaves to die for their protection.
These are not the only xenos engaged in combat through the Mortis Thule, as the Orks aboard live for little else. The sight of the Mortis Thule drives Mekboys by the thousands to prepare ramshackle force-bubbled rokkits; these ferry mobs into the void and to the space hulk where they use the random travel it provides to bring them to new systems for raiding and conquest.
Once the space hulk reappears they launch themselves at whatever they can find, continuing their WAAAGH! into areas unready for such devastation.
There are few Ork worlds in the Jericho Reach, due perhaps to successful eradication policies carried out during the Great Crusade, and Imperial scholars believe many of the Orks aboard the Mortis Thule originated from other sectors. This possibly means the space hulk travels even further than suspected, and may bring even greater horrors in future visitations.
While the Orks live for combat, for many of the Humans stranded inside the Mortis Thule there is only the endless struggle to survive. Most have become little better than animals, devolving after exposure to radiation and Warp-induced mutagens into bestial Hullghasts.
They roam from hull to hull, migrating as decks lose air or water seeps away into the rock-loam binding ships together. Each is a perversion of the Human form; bleached scabrous skin with eruptions of horn and bone, long fingers of talon-like nails, oversized mouths filled with rotting but needle-sharp teeth. Any they find in their way becomes new food, as do the weaker of the tribes should their hunger grow too powerful.
Deep within the Mortis Thule there are others also fighting to survive but still retaining a semblance of their Humanity.
The courier Emperor's Gaze was trapped many Terran years ago near the end of the Achilus Crusade's initial successes when their Navigator failed to detect the space hulk drifting near them in the Warp. Surely the God-Emperor's gaze was indeed upon them, for they managed to stay alive in the years since in that forced union.
Carefully rationing their remaining power to keep their now-priceless Gellar Field intact when the Mortis Thule returns to the bosom of the Warp, and sustaining themselves on meagre supplies and fungal growths, they must also fight off raiders eager to steal their functioning systems.
Their prayers are perhaps their greatest defence; the reverberating devotional hymns rise above the foul chatter of the tainted xenos such that some explorers have found themselves unknowingly joining in the song. One day they may indeed be rescued but until that day comes, they know their Emperor surely watches over them.
These are but a few of the dangers and denizens to be encountered on Mortis Thule. Accounts tell of many others, such as the rapacious Voar xenos-infection, feral Kroot-beasts and their carnivorous handlers, piratical Aeldari in gleaming barbed armour and dripping blades, and far more that dwell in the depths of the Mortis Thule.
Each boarding reveals new occupants, eager to welcome those who dare visit their tomb of rock and metal.
- Deathwatch: The Achilus Assault (RPG), pp. 61-65