Mogontiacum

Deep within the frozen veils of the Glacial Nebula, there lies the single greatest bastion of imperial might, one stalwart defense impenetrable, the sole hearth of warmth among the Borealis Stars: This is the Starfort Mogontiacum, first Castellum of all the Limes Gondwana, the seat of the Imperial Navy's Battlefleet Gondwana.

Its name, seldom spoken, is infamous among the mighty ones of the Triumvirate, for it represents the Imperium of Man at large - its cabals and feuds, and the chains which bind all domains of humanity together. Despite the distinct silence surrounding the lonely fort, nothing is ever said or done without the knowledge of those distant masters who reside in cold Mogontiacum.

## Astrography

Mogontiacum exists in near-complete isolation, far removed from the rest of living Sector Gondwana. Buried deep in the shrouded heart of the Glacial Nebula, no vessel could easily reach the fort, at least not without a navigate of the solely initiated dynasty residing upon Mogontiacum.

No common trading routes nor regular deployments lie there, where the winds of the glacial nebula sweep the void with cosmic snow, and ships are swallowed ever so often by the unnatural grasp of unholy tides.

To the rest of Sector Gondwana and its valiant voidfarers, the Nebula and its fort are a dangerous mystery. Those who wield power know to fear the Imperium for its omens of doom. Those not knowledgable enough fear the region instead for dangerous monstrosities of local legend. In both reasons, some say, resides a kernel of truth, and all agree unanimously to leave Mogontiacum to itself, so long as it does not reach out to them on its own.

## Seat of Battlefleet Gondwana

In the cold halls of Mogontiacum sits the *Dux Mogontiacensis* of the Imperial Navy, appointed by the Lord High Admiral of Segmentum Obscurus, in the name of the High Lords of Terra.

The arrival of the Imperial Navy was an unfortunate one, many hundred years delayed by throes of the warp, indecision and Imperial Bureaucracy. The forces of the Imperium at large were never welcomed in these parts since their withdrawal from the Great Crusade, and have been stationed in separation from the sector's civilized worlds. Cold silence is between them and the Triumvirate, even though the latter's loyalty remains uncontested.

Nonetheless, countless souls are driven into convoys toward the Glacial Nebula with each passing decade, as part of the Imperial Tithe collected within Mogontiacum. From those raw souls of so distant origin, the lords of the Battlefleet Gondwana forge their own, strange kin. After their training and indoctrination, the voidsmen of Mogontiacum are stoic and distant, changed from whatever they truly were before.

More than anything else, they keep the secrets of Mogontiacum, adding to the endless mystery surrounding the Navy standing watch over these worlds.

### *Dux Mogontiacensis*

The authority of all imperial naval forces in Sector Gondwana lies with the Dux Mogontiacensis, Commander and Lord of the Star Fort, and the Castellum Forces. By the power vested in this hallowed individual by the Imperium at the hands of the hierarchy of Segmentum Obscurus, this elusive Admiral holds sway over every last void ship, safe for those of the Explorators directly commanded by the Adeptus Mechanicus.

In cycles of roughly three hundred years, the position of Dux Mogontiacensis is reassigned among the endlessly complex web of command within the structure of the Imperial Navy. To even think for a soul of the Sector Gondwana itself to ever take this throne is unheard of even among the most ambitions elders of the Triumvirate. Thus, the role of the Dux is held by unseen women and men, established by the powers that be according to rules and declarations unheard among Gondwana's constellations.

Yet, with the Crusade of Brass and Iron, a crucial time might have come, when for the first time in millennia, the Dux would take up the true mantle of their authority and wield the fleets of the sector truly as the emperor's blazing sword to vanquish the enemy.

## Fort Mogontiacum

Mogontiacum is a mighty fort and harbor to the Imperial Navy, but first and foremost, since ages long forgotten, it has been a lighthouse on the northern frontier. Its light pierced the relentless dark to unveil what lay hidden in the abyss between galaxies.
One day, more than ten millennia ago, it was answered by a million bleak reflections.

At its heart still, burn many fires to ward off the cosmic cold encroaching onto Sector Gondwana. These flames fueled by arcane energy project an intangible field beyond even the stellar spheres of the Borealis Stars, and they provide the sole safe passage to and from Mogontiacum. This, its ancient purpose, remains the star fort's greatest defense. Should any foe ever come to besiege the mighty station and all hope for victory be lost to its masters, the flames will be extinguished and all things freeze in the absolute cold of the glacial nebula.

### Station Without Secrets

Many legends surround the First Castellum Mogontiacum, the most unsettling of which claims there to be no secrets, no single uncertainty to remain in the vaults of this station. In a galaxy scarred by nigh twenty millennia of oblivion and decay, the mere notion of one such ancient star fort being fully grasped and controlled by the Imperial Navy is a most unusual occurrence. This fact alone, should it be true, would tell more of the fabled power and influence of the Imperial Navy than any number of vessels, any grand display of military might could ever match.
Such an achievement would overshadow nearly all efforts of the Cult Mechanicus Cambria, the grand designs of the Ecumenopolis Trantor and even the honor held by the Astartes of the Hallowed Glaive.

But attached to this legend of Mogontiacum's greatest achievement are also rumors of much darker implications. For whatever secrets once lay at the heart of this station, at least some of them surely must have been tainted. And for them to have fallen into the hands of the Imperium without any repercussion seems too good to be true, too easy of a victory in a galaxy of eternal strife. The darkest forces, so they say, are those who work entirely unseen, those who feign perfection only to hide away the very darkest of secret horrors.

### The Structure of Mogontiacum

Measuring just over twenty-eight kilometers in diameter, the Star-Fort Mogontiacum is neither the largest nor the most fortified station on the fringes of the Thetys Rift. It is, however, a unique marvel since its occupation by the Imperial Navy, as those voidsmen from afar brought countless wonders and artifacts to Gondwana which are nowhere to be found anywhere near the sector.

### Tiered City

The entirety of Mogontiacum was designed to accommodate the navy, and nowhere is its utility more apparent than in the hab-blocks and service decks of the Tiered City. It is here that most of the voismen live out their lives, on the great terraces surrounding the armored heart of the station.
At first glance, the city might appear not too different from the common imperial hive. Only upon close inspection of records detailing efficiency and resource-management, the true genius of its design becomes apparent. Unlike the spires of a hive growing over centuries without guidance, every last inch of this station was carefully planned out and designed, created to perfect specifications and set up in a way to optimize every aspect of life.
Striking a perfect balance between spartan utility and imperial splendor, the Tiered City offers a living standard and safety exceeding most worlds in the sector, and this makes for the most efficient workforce at the disposal of the Imperial Navy.

### Bastions

The Upper Bastions house the greatest weapons of Mogontiacum, which far exceed the conventional weaponry of the star forts regular battlements. Within these bastions reside massive long-range artillery pieces, mass accelerators and superheavy lances the likes of which have grown rare in the Imperium since the Great Crusade. The Bastions of Mogontiacum are renown for its ancient arsenal, guarded by the waking minds of old machinery to which an entire cult of the Mechanicus is specifically devoted. Masters of faraway Forge World travel for centuries to serve these formidable weapons and ensure their worship continues without degeneration.

The Upper Bastion stands out for its cyclopean lance, which is fueled directly by the station's central power. At the cost of shutting down all secondary systems of the station, this weapon of supreme destruction can unleash a fire so great it will incinerate the foe completely. Scarcely, in all the station's history, has this weapon been used, but records exist of this rare occurrence, and great murals of them decorate many of the station's halls.

### Mogontiacum Dockyards

The true purpose of Mogontiacum, however, lies in the large dockyards and fleet installations covering most of its outer rings. These house drydocks and silos, storages and repair yards fit to accommodate the needs of the Imperial Navy. They are not most impressive because of their size, but the singular efficiency with which the duties of these facilities are performed. More closely resembling the capabilities found on the Imperium's core worlds, compared to all stations so far out in the galaxy, the dockyards of Mogontiacum are unparalleled by anything in near constellations.

How such feats are achieved by the priests and engineseers of the station is a secret well-kept in such dangerous parts of the galaxy. But rumors exist of supply runs coming from the inner galaxy to restore components and entire machines with resources not found anywhere in Sector Gondwana.

### Manufactorum and Forges

If the dockyards of Mogontiacum are renown for their efficiency, the forges and manufactorum are almost feared. It is well known these massive assembly halls do not truly create their machines from raw resources as most forges out on the galactic fringe do. Instead, these are merely assembly halls for parts pre-built far closer to the center of the galaxy – closer to the Red Planet where the true revelations of the Omnissiah reside.
Sometimes, it is said, the forges of Mogontiacum are even supplied with broken vessels and damaged ships from battlegrounds throughout the galaxy, refurbishing vessels after their first defeat so that they may be resurrected and brought into service again.
What is the last resting place for broken vessels in the eyes of the inner galaxy, is indeed an influx of unique and formidable technology to the shipwrights of Mogontiacum. And through their handiwork, legendary vessels sail again through the void near the Thetys Rift. From such ancient sources arises the famous power of the Castellum Fleets.

### Inner Columns

Along the central axis of the station, the inner columns offer protection for all which is surrounding them. Here lie the power cores and void-shield generators, arranged in overlapping patterns. An entire grid of defensive weapons systems and countermeasures, even stores of malicious cybernetic viruses and bio bombs are housed in the vaults of these columns, under the oversight of an entire hierarchy of navy officers appointed by the Segmentum command.
The inner columns are as isolated from the rest of Mogontiacum as Mogontiacum itself is from the rest of the sector. Solemn, they rise above the spires of the tiered city and stand guard as silent protectors, taking in few recruits from the best of the outside world, but never letting any secrets out.

It is rumored that if anywhere, the lairs of the Rhenuskin would lie somewhere within these columns as well. And while perfect records of them are said to exist, only the highest members of the Imperial Navy could ever risk requesting to see them.

### Hearth

The innermost sanctum of Mogontiacum is the Hearth, where the fires of arcane machinery burn. Little is known about the old artifact of ages past, at least to the mortal souls outside the circle of the master of the flame, the keeper of the light which holds the cosmic cold of the Glacial Nebula at bay. The secrets of this ancient machine are only passed between this master and his successor, and so they have for many generations. Few adepts are chosen to carry out their duty near this flame, and they never leave this place, until their bodies are burnt in the furnaces fueling the Hearth as well.

It is this ancient core at Mogontiacum which constituted the original purpose of the station. Anything else is just decorative in comparison, additions made by later generations to the lighthouse that is the star fort Mogontiacum.

### Two Towers

Below the bulk of the station, two towers, in particular, stand out amid the many domes and spires carefully placed by the architects of Mogontiacum. These house the choir chambers of the astropaths, from which messages are sent to the inner parts of the Imperium. Safe for a singular station on the Elder Frontier, this is the only direct line of communication between Sector Gondwana and the Galaxy at large. From here, any message of victory or disaster will be sent, and here lies also the dead man's switch of the Imperial Navy. Should Mogontiacum fall or for any other reason fail to send a message every one hundred and seventeen years, then an expedition of the Imperial Navy will be sent to discover the reason for this disruption. By comparison to the other Imperial Sectors so far out on the fringes of the Galaxy, this is a remarkable level of imperial observation. To those few who have laid eyes upon them, the two towers of Mogontiacum are the single best measure to describe the true importance of Sector Gondwana, to the rest of the Imperium. It speaks also to the Imperium's nature, how secret these towers and this information are.

### Open Dungeons

At the lowest point of the star fort Mogontiacum, there lie the open dungeons and construction sites, remnants of a much older intention long forgotten. While they have been dormant for nearly nineteen millennia, these old sites still tell of a much grander plan devised by forgotten architects for the outer station of Mogontiacum. Great chunks of raw material persist in these lower regions of the station, waiting to be transformed into new modules of ancient design. So holy are these forgotten sites of creation, that not even the authorities of the Imperial Navy deemed it an option to use these materials to bolster their forces. These open dungeons are monuments to a great era that could have been, and they won't be finished until the vision of the Emperor will finally come true and the greatness of the old days is finally reclaimed.

## Before the Cosmic Winter

Mogontiacum is an old station and its history exceptionally well recorded. It is said not a single day has gone by on Mogontiacum without being properly noted in the archives of its machine spirit. Not only are these archives extensive, but also uniquely well preserved. While holding little information about basic technologies and system designs, these do offer a rare glimpse of ages that were and worlds which could have been.

What is truly written on those countless slates of data is a well-guarded secret among the highest circles of imperial authority on the station. Yet in reality, the most remarkable thing about these records is their overwhelming mundanity as compared to the overladen pathos of all the imperium. Something truly powerful lies in the simplicity of these reports, which even remained distant and unaffected even as the cosmic snow began enveloping the station. Whoever wrote the first thousand chapters of those ancient records was a pure observer of the world, seemingly completely removed from its physical reality.

## First Castellum of Limes Gondwana

The sole point of regular contact between the souls of Mogonticaum and the rest of Sector Gondwana are the remote starforts and castella along the Limes Gondwana, whose garrisons are themselves exiles among the peoples of the Triumvirate. In lone, cold places, on the fringes of the charted void, those divided forces stand united against the oncoming storm. From those serving with troops of Mogontiacum, a scarce few are chosen to serve upon the first Castellum itself, becoming part of the uppermost command structure directing the efforts of the imperial defense. These become ambassadors to Trantor, Cambria, and Nimbus Laurentia, for they are still souls of common kin with the peoples of Gondwana, yet changed enough by Mogontiacum to understand the ways of the Imperial Navy stationed there.

As the first fort of the Limes Gondwana, Mogontiacum has stood for long eons as an unconquered point of defense, breaking the tide of threats during the Thetys Surge. Very little is known about the Glacial Siege during the Thetys Surge when all of Sector Gondwana was under threat of being overrun and would have been lost had not Mogontiacum held out somehow, against all possible odds.

## The Rhenuskin and the elder blood of Mogontiacum

Among the oldest, most knowledgable souls in Sector Gondwana, there exist rumors about the peculiar nature of the Battlefleet Gondwana, ever since its stationing upon the lone fort Mogontiacum.

They tell of the Rhenuskin, an old, forgotten people, who lived upon Mogontiacum even at the time when the Crimson Queen was young. They were neither truly human nor true Xenos in nature, and harbingers of the cosmic cold before the greater winter came.

The Rhenuskin, they said, knew ways of gods older than the race of man, and secrets feared even by the Ringmakers of Cambria. They had a kinship with something old and terrible lurking within the Borealis stars, coming from the great galactic north and from beyond the fringes of the endless void.

And although no such eldritch horror had even been described or seen by any soul, the mere shadow of them still tinged the blood and souls of those who lived upon Mogontiacum. And through the Rhenuskin was born a bastard-race which had some ways of surviving in the winter such elder things brought.

It is further said such legends were known to the Imperium, and that Battlefleet Gondwana was sent on behalf of some unknown powers that be. Some souls presume its purpose was indeed not the protection of the sector, but to seize those arcane secrets before the Triumvirate ever could.

Nobody knows whatever became of the Rhenuskin, and if they were indeed ever more than the stuff of legend. But this theory above all is often cited as the explanation for the strange changes undergone by all those recruited into the ranks of the Imperial Navy Seat Mogontiacum: That the Rhenuskin's blood still flows through some veins of their leaders and is handed down to all who set foot on this cold station.

## Death and Duty

Chosen ones among the mortal billions of untold distant worlds, the voidsmen of the Castellum Fleets of Mogontiacum serve with an unrelenting sense of duty, unwavering even when facing the inevitability of doom in the depthless abyss of the Thetys Rift. It is this absolute loyalty to the imperial cause which overshadows all legend regarding the Rhenuskin and the tainted blood flowing through the lineages of officers and honored crew in the ancient fort.

## Forces

### Castellum Fleets

Hailing from the forges of frozen Mogontiacum, the voidships of the Castellum Fleets are of ancient, powerful lineages, following patterns unknown to the rest of Sector Gondwana. Within them, they carry secrets of technology and past enlightenment only trusted to the hands of powers beyond the confines of one sector, and as such, they wield the power of incalculable potential.

However, vessels of their ranks larger than light and common cruisers, are nearly completely the subject of an old legend, so rarely are they seen outside the Glacial Nebula. No-one truly knows what strength lies between its frozen veils, but many a legend places even grander, ancient wonders there.

### Principes *Mogontiacensis*

Those veterans of the Castellum Classis reside as garrisons on many forts, silent custodians of the Limes Gondwana. Their stoic formations, standing alone or in closed ranks on their posts on stations manned otherwise by common souls of the No-Man's-Land, are the source of most myths and legends about the nature of all people upon Mogontiacum. It is said that they remain silent and still as to not share any secret and show any sign of what they have seen on their travels cruising close to the Thetys Rift.

Their stoic silence does not break even in battle, which they conduct with cold and brutal efficiency. However, they still bleed the same blood as their comrades and brethren and have been known to show gestures of compassion and mercy in the aftermath of defeat and victory. There is still some kinship between them and those born under the No-Man's-Land's constellations, notably more so than between them and any other region of Gondwana.

## Relations

For most of imperial history, Mogontiacum stood isolated, a lone bastion of the Imperium in the distant realms of Sector Gondwana. It is a twisted mirror image of Sector Gondwana itself in relation to the Imperium at large, from which it is far removed by the nigh inter-galactic gulf.

What knowledge the worlds of Gondwana have is diluted by myth and legend, and they seek little more to remember, for what little memories they have are no good ones of this secretive power lurking in the glacial cold. And nonetheless, the Imperial Navy is met with undeniable respect and admiration wherever it's mighty vessels show.

## History – the Navy's Arrival

When the High Lords decided to draw a line around their charted stars, the border of the Imperium split Sector Gondwana in half. And to guard mankind's worlds against the dangers of the Thetys Rift, a Battlefleet was formed in accordance with the rules the Imperial Decree declared.

Battlefleet Gondwana was late to be founded, long after the Archheresy had come to pass. And the loyal worlds on the safe side of the Thetys Rift had already entrenched themselves as best they could. Its request and founding documents had swallowed in the endless maze of the imperial bureaucracy. And yet, even at that time, some conspiracies persisted, of a more sinister design beyond the apparent lack of competence on behalf of the Administratum.

*The emperor's chosen from many worlds afar were sent to the frontier to hold the darkness at bay.*

Thus it was written in the hallowed light of Sol. By order of the High Lords, the Imperial Navy came upon Sector Gondwana, a force mighty and formidable, to secure a bastion on the rift. Without notice to any who deemed themselves on Gondwana's throne, the battlefleet arrived unannounced upon the Elder Frontier.

At Old Burg the forces of the Imperial Navy were met by one rapidly assembled force coming from all havens of Gondwana. As the fleet was washed ashore from beyond the abyss between the galaxy's spiral arms, the Imperial commanders were disoriented, lost under distant suns and faced with a force no less formidable than their own.

For many long hours, there was uncertainty on both sides on the nature of their counterpart, local forces of the Triumvirate hailing and answering the calls of the Imperial Navy.

Only when aboard a mighty battleship, two mortal souls met face to face, was there certainty about the common nature of their kin and the Imperial Navy's faith the loyalty of the Triumvirate was restored. And for this single, one occasion, the Imperial Navy made one great parade. Its formations formed new constellations and blocked out the natural sky on many inhabited worlds of this sector before they reached their first and final resting place in the glacial ice of the Galactic North.

As they approached the Glacial Nebula, one after another, the local forces peeled away, until the Imperial Navy was only led by a single ship mysteriously unknown to any other authority, though unmistakably of Imperial design. It was this unknown pilot vessel which brought the human voidsmen to the Fort Mogontiacum. There, in an inhospitable nebula, the vessels of the fleet and their souls made a new and permanent home, embellishing the spire of the cyclopean station.

Many, since then, have not moved from their berths safe for the direst times in recent history, first among these the Surge of the Thetys Rift. Yet even for all this secrecy, their legend still precedes them.