Cadia – Gateway to the Eye


With the Gathering Storm just getting started, we thought it’d be a good time to learn about Cadia. So we caught up with Citadel Writer Phil Kelly to tell us about this lynchpin of Imperial defence.

Cadia is a world synonymous with the indomitable, obstinate denial of the Ruinous Powers. It has stood sentinel over the Eye of Terror for time immemorial, and withstood every assault the powers of Chaos have thrown at it. But a great storm is gathering…


To fully understand the Cadian people and their way of life, it is necessary to go back more than ten thousand years, to a time lost in legend. The planet now known as Cadia was first colonised at some point in the Age of Technology. When it was found again during the Great Crusade, a degenerate human civilisation still remained. Despite, or perhaps because of, it’s proximity to the strange influence of the Ocularis Terribus, this population had endured the Long Night and taken to worshipping the great Warp rift that dominated their sky. The Emperor’s Great Crusade had no tolerance for this sort of belief system, and by the end of the Horus Heresy, the civilisation had been cleansed from the surface of the planet with the cyclonic torpedoes of Exterminatus.

Now known as Cadia, this planet witnessed the tail end of the Traitor Legions’ rout from the Siege of Terra as they retreated into the Eye of Terror. Despite the devastation caused by Horus’ rebellion, Cadia had been quickly resettled and fortified, and so began it’s watch over the Cadian Gate. The Cadian Gate is the most reliable route to and from the Eye of Terror, and it seems to be roughly centred on the planet of Cadia itself. As such, is one of the most strategically vital worlds in the Imperium. Though there are theoretically other routes from the Eye, they ebb and flow with the unpredictable storms of the Warp, and no force of any size can venture forth without first passing through the becalmed space around Cadia.

Late in the 31st Millennium, the planet was ready to stand against the first of the Black Crusades. Although the Imperium was ultimately victorious, thanks in large part to the newly raised Space Marine Chapters and Legio Titanicus, the early defences proved undermanned, and the planets of the Cadian Gate were further reinforced. Since those earliest of days, Cadia’s fortifications have never stopped being rebuilt and improved upon and added to. The same Traitor Legions that besieged Terra still lurk in the Eye, fighting in service to their monstrous gods, and they, too, have never stopped. They fight against each other to prove their supremacy, and fight against the forces of the Imperium when the Warp storms calm long enough to allow them to rampage into realspace from their Daemon-infested strongholds. 

The lynchpin of the Cadian Gate’s defences is the planet itself, and more specifically, the people who live there. Cadia is a bleak, merciless and wind-blown orb, where only the strongest survive to adulthood and discipline is learned at the earliest age with the Eye ever glowering in the sky above, even in the daylight hours. Cold winds howl across wide, sundered plains while armies train with live ammunition and every day not spent training and testing the defences is a day wasted. Every city, or kasr, is a fortress of bewildering scale, with its streets and buildings fashioned with great tactical cunning by the finest military architects.


Cadia’s entire populace is destined for a military life; the birth rate and recruitment rate are synonymous. Cadian regiments are highly efficient, excellent in combat and use elite veterans to lead their attacks. Their Shock Troops have perhaps the most hazardous duty of any Imperial body – to defend against Chaos incursions. One Cadian soldier in every ten is recruited into the Interior Guard, regardless of ability or achievements, and as a result, some of the most able soldiers spend their entire military service on Cadia, waiting for an army of Chaos to emerge from the Eye for them to fight. The other nine in ten are sent to other war zones across the Imperium, there to impart a measure of their excellence to the armed forces of the other regiments that form the vast body of the Astra Militarum. Their reputation is well founded, and the Cadian Shock Troops are amongst the most effective and skilled fighting forces in the Imperium.

Any Cadian who can’t field-strip his own lasgun by the age of ten was born on the wrong planet.

– Anon

Every Cadian is taught the skills of the warrior as soon as they can walk, and they are much sought after by commanders throughout the galaxy. Such a planet breeds hardy and determined warriors, and the Cadian regiments have a well-deserved reputation for both honour and fighting spirit. From the earliest age, they are taught to field strip a weapon with their eyes shut, memorise lengthy hymns of purity and banishment, and run through fields of barbed wire with heavy weights strapped to their backs; tactical doctrine is taught before reading and writing. The standards they are held to are exacting, brutal and unrelenting for the whole of their lives. Each day, the knowledge of their own deaths is ingrained in them as their training reiterates and reinforces their strength and core purpose: to fight and die in defence of the Imperium against every force, no matter how vast or profane, that confronts it. 

Thus far, they have not failed. Thus far, Cadia stands.



The mysterious, monolithic pylons of black stone that dot the surface of Cadia predate humanity’s settling of the system entirely – they jutted from the windswept wastes to greet the first groups to make planetfall, and have been a source of much debate ever since. Whether they remain standing after the violence of Abaddon’s 13th Black Crusade, however, remains to be seen.

Each pylon is vast, though they are not uniform; most stretch thousands of feet into the sky and extend more than a thousand feet below the surface. None of them have been successfully dug up. The upper facing of the smooth black stone has been machined by some unknown force with complex sets of holes cut into the surface evincing a stunning degree of craftsmanship. These lead to bewildering geometries within the stone, and through these slim tubes, hundreds of feet long, the wind of the Cadian wastelands moans and shrieks.

Thus far, the precise form of these interior tunnels has baffled all attempts to categorise or measure them. The Tech-Priests that have investigated these artefacts sent every manner of probe servitor and servo-skull, some no more than a hand’s breadth in diameter, intending to map the loops and convolutions inside the pylons, but few return, and never with conclusive data.

Five thousand, eight hundred and ten known pylons dot the surface of Cadia, with another two thousand others remaining as partial ruins or buried relics. No two are identical in design. They are totally inert, by the readings of any auspex used to scan them, though there are many theories as to their true function. Similar structures have been found and catalogued in several locations across the breadth of the galaxy, some freestanding, others incorporated into larger structures or even buried far beneath their host planet’s crust. The most abiding theory is that they are somehow linked to the fact that Cadia is largely untouched by the tides of Chaos – that they are the reason the fortress planet abides at the heart of the most stable region of space in a truly tempestuous sector.

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