Cadia Prime
Type	Civilised World / Fortress World
Orbital radius	1.32 AU
Gravity	1.12 G
Temperature	20 Degrees C
Population	850,000,000
System	Cadian System
Sector	Cadian Sector
Segmentum	Segmentum Obscurus

Cadia, officially known as Cadia Prime, is a terrestrial, Earth-like planet that has been classified as both a Civilised World and as the Imperium of Man's most important Fortress World by the Administratum. It guards the only known navigable route to and from the massive Warp rift known as the Eye of Terror, a passage called the Cadian Gate. The world's dangerous proximity to the Eye of Terror has made it necessary for the people of Cadia to heavily fortify the planet. Cadia is always the first target of the Chaos Warmaster Abaddon the Despoiler's assaults and Black Crusades, when the Forces of Chaos Undivided launch themselves from the Eye of Terror every few centuries in an attempt to break out and invade the Imperium proper as they did during the Horus Heresy. Cadia's natural environment is much like Terra's was millennia ago, with a large ocean covering 70 percent of the planet's surface. The land mass that does exist is divided between incredibly thick pine forests and vast glaciers. The planet is slightly cooler than most human-settled worlds but not to the point that it adversely affects growing conditions. Settled before the onset of the Age of Strife by a branch of humanity that eventually fell to the worship of the Chaos Gods and played a major role in the ultimate corruption of the Space Marine Legions, Cadia was re-settled sometime in the early 32nd Millennium by Loyalist humans of the Imperium. The world's landscape is dotted by strange black pylons of clear xenos origin called the Cadian Pylons. These devices were actually constructed by the Necrons millions of years ago to hold back the psychic energies of the Eye of Terror from the world, which was an ancient Necron military base during their war with the Old Ones. The Cadian Pylons are what create the unusual area of realspace stability known as the Cadian Gate near the Eye of Terror that is unaffected by the constant Warp Storms that surround that Warp rift. Cadia's location directly adjacent to the dangerous Eye of Terror has made it necessary for the people of Cadia to fortify the planet to an extent where almost the entire population lives in massive fortress-cities known locally as "Kasr". Thus Cadia has an odd mix of dense urban areas and vast open tundras and other natural landscapes. It is always against Cadia that Abaddon the Despoiler, the Warmaster of the Chaos Space Marines and the Forces of Chaos, fields his continual assaults or Black Crusades from his hold in the Eye of Terror.

History

Pre-Heresy

Some 40 standard years before the outbreak of the Horus Heresy, Cadia was a world inhabited by a primitive race of violet-eyed humans who worshipped the four Chaos Gods, probably a remnant of Mankind that had turned to the Ruinous Powers during the hardships of the Age of Strife. Prompted by the so-called Pilgrimage of the Primarch Lorgar of the Word Bearers Legion to discover whether or not the Gods once worshipped by adherents of the Old Faith of the Word Bearers' homeworld of Colchis actually existed, Lorgar journeyed with his Word Bearers Legion's Chapter of the Serrated Sun to what was then the fringes of known Imperial space as part of the 1301st Expeditionary Fleet of the Great Crusade. At this time, Lorgar had not yet fallen to Chaos, though he had turned against the Emperor of Mankind as a deity no longer worthy of his worship after the Emperor and the Ultramarines had personally humiliated him and the entire Word Bearers Legion on the world of Khur 43 years before the start of the Horus Heresy. The Emperor had come to Khur personally with Malcador the Sigillite after ordering the Ultramarines to destroy the Khurian city of Monarchia where the Emperor was worshipped as a God as a result of the teachings of the Word Bearers. He made his displeasure known to Lorgar about the Word Bearers spreading the religion of Emperor-worship to every world they brought into the Imperium, in direct contravention of the rationalist, atheist philosophy of Imperial Truth. The Emperor forced the entire Legion to kneel against their will through the use of his psychic might and then explained that they were the only Astartes Legion to have failed his purpose on the Great Crusade. After this humiliation Lorgar, on the advice of his First Captain Kor Phaeron and the Word Bearers First Chaplain Erebus, decided to undertake a Pilgrimage to discover if the Gods worshipped by the ancient Old Faith of Colchis were real and worthy of the Word Bearers' faith and allegiance.

The Word Bearers were also accompanied on this Pilgrimage by 5 members of the Adeptus Custodes who had been set by the Emperor to watch over everything the Word Bearers did to prevent them from falling back into error once more. The 1301st Expeditionary Fleet exited the Warp near the largest Warp Storm in the universe, later known as the Eye of Terror. The Fleet's Master of Astropaths advised Lorgar that unusual "voices" in the Warp were heard in the vicinity of the great Warp rift, voices that spoke directly to the Primarch as well, the voices of the Chaos entities within the Immaterium.

The decision was made to hold orbit over Cadia and for the 1301st Fleet's elements to make planetfall on the unknown world, designated as 1301-12. The landing force was comprised of Imperial Army, Word Bearers, Adeptus Custodes and Legiones Cybernetica elements. The landing party, led by Lorgar, was greeted by a large number of barbaric human tribes, tribes described as "dressed in rags and wielding spears tipped by flint blades...yet they showed little fear." Most notable were the barbarians' purple eyes, which reflected the colour of the Eye of Terror itself in the spectrum of visible light. Despite the Custodian Vendatha's protests and request to execute the heathens, the Word Bearers approached the natives. A woman emerged from the crowd and addressed the Primarch directly, calling him Lorgar Aurelian and welcoming him to Cadia. This woman, the priestess Ingethel, would ultimately lead the Primarch down a path of spiritual enlightenment that actually marked the beginning of Lorgar's fall to heresy and Chaos. Later, the Priestess Ingethel of Cadia would lead the 1,301st Fleet's scout vessel Orfeo's Lament into the Eye of Terror and thus change the Word Bearers forever as they were exposed to the Ruinous Powers of Chaos and slowly corrupted, the first of the Legiones Astartes to worship the Chaos Gods and become Traitors to the Emperor. The Cadians, primitive as they were, used a language which was akin to the Word Bearers' own Colchisan tongue. Many traditions of the Word Bearers were mirrored by the culture of ancient Cadia, leading Lorgar to believe that the original settlers of both his own homeworld of Colchis and Cadia shared a common heritage.

Following the visits into the Eye of Terror, Lorgar ordered a cyclonic bombardment of the planet, wiping out the Cadians and leaving the planet abandoned.

Post-Heresy

Following the Battle of Terra that ended the Horus Heresy with Horus' death and the internment of the Emperor of Mankind in the Golden Throne, the defeated Traitor Legions and their allied forces among the Imperial Army and the Dark Mechanicus fled from Terra. Some of the exhausted Loyalists rallied and gave chase, but most remained on Terra to consolidate their great victory over the Forces of Chaos. Many of the Traitors were put to the Chainsword, but the majority of the Traitor Legions escaped into the great Warp rift known as the Eye of Terror in the Segmentum Obscurus, a region of space where reality and the insanity of Chaos collide as the raw psychic energy of the Immaterium pours into real space-time. In the Eye of Terror, the Chaos Gods rule over uncounted numbers of planets, all warped to reflect their own dark aspects. It was there that the Traitor Legions found refuge, isolated from the rest of the galaxy by potent Warp Storms. Each of the planets within the Eye is a Daemon World, warped and twisted by the whims of the Ruinous Powers and the powerful Daemon Princes who rule over them in the Dark Gods' name. The Chaos Space Marines regrouped and nurtured their hatred of the Imperium, planning for the day when they would wreak a terrible vengeance on those who had defied them and their foul masters. Within the Eye time flows differently than in realspace. Those same Traitors who fought on Terra 10,000 standard years ago still fight today in the service of Chaos. They fight against each other to prove their supremacy and against the forces of the Imperium when the Warp Storms calm enough to allow them to emerge into Imperial space. The Imperial sectors surrounding the Eye of Terror are heavily militarised to resist these frequent invasions and none more so than Cadia, the Fortress World that stands at the very mouth of the only stable navigational route leading out of the Eye of Terror, the dreaded Cadian Gate. The planet's extremely strategic location meant that it would prove useful to the Imperium and in the 32nd Millennium Imperial colonists were dispatched to resettle the world, becoming the ancestors of the present-day population of Cadians. Perhaps as a result of the Eye of Terror's proximity this later population of Cadians also soon developed the unusual violet-coloured eyes that had marked the first human inhabitants of the planet.

Cadia stands upon the only known reliable route out of the Eye of Terror and thus is one of the most strategically vital worlds in the entire Imperium of Man. There are other routes out of the Eye, but none are stable like the Cadian Gate and no military force of any true size can venture forth from the Eye without first passing through it. The exact reasons for the existence of this unusual region of stability is unknown, though many Magos of the Adeptus Mechanicus believe it is due to the presence of the famous Cadian Pylons. These mysterious black monoliths, now known to have been created by the Necrons  millions of years ago to hold back the psychic influence of the Warp that was so feared by their C'tan masters, dot the landscape of Cadia and their origins remained mysterious until the time of the 13th Black Crusade.

Cadia itself is a bleak, merciless and wind-blown planet, where only the strongest survive to adulthood and discipline is learned from the moment a babe takes his or her first steps. Cold winds howl across wide, sundered plains where armies train with live ammunition and every day not spent training is believed to be a day wasted. Every Cadian fortress-city, or "Kasr", is a great citadel, with the streets and buildings fashioned with great tactical cunning by the finest military engineers and siege specialists of the Imperial Guard. 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. Cadian military gear is considered top-rate and is used as the standard for all Imperial Guard Regiments. Such a world breeds hardy and determined warriors and the Cadian Regiments of the Imperial Guard have a well-deserved reputation for both honour and fighting spirit. From the earliest age, Cadians are taught to field-strip a weapon with their eyes shut and tactical doctrine is taught before basic literacy. One soldier in every ten is recruited into the Cadian Interior Guard, regardless of ability or achievements, and as a result some of the most able soldiers spend their entire Imperial military service on Cadia and the soldiers of the Cadian Planetary Defence Force are amongst the most skilled fighting men in the Imperium, the equal of many other worlds' Imperial Guard Regiments.

13th Black Crusade

In 999.M41, when Abaddon the Despoiler finally launched his 13th Black Crusade, the greatest Chaos assault on the Imperium since the Horus Heresy, the Forces of Chaos managed to make landfall upon Cadia itself and occupy large swathes of the planet despite ferocious Imperial resistance. Led by the Lord Castellan Ursarkar E. Creed, the Imperial forces were ultimately able to contain the Chaos assault but they could not force the Traitor Legions to leave the planet. In the space above Cadia, the Imperial Navy proved victorious over the Chaos warfleet led by Abaddon while the Eldar provided a timely assist in facing off against a Blackstone Fortress inhabited by a sentient avatar of Slaanesh himself. At the end of that campaign, the Imperial Navy controlled the space over Cadia and thus prevented the Forces of Chaos from breaking out of the Cadian Gate, yet at the same time the Traitor Legions and their allies remain in control of a large amount of Cadian territory. They have dug in and erected elaborate defences that will prove very difficult for the Imperial forces to overcome. As a result, at the present time, a bloody stalemate reigns on the Imperium's most important Fortess World, though if the Forces of Chaos were ever able to seize the orbital space over Cadia, they might at last gain the advantage necessary to fully conquer the planet and overwhelm the remaining defences of the Cadian Gate. Should they do so, then the Imperium may face the greatest threat to its existence since the Horus Heresy, 10,000 years ago...

Society

Cadia is the home of the Imperial Guard's Cadian Shock Trooper Regiments, widely regarded as the best soldiers in the Imperium short of the superhuman Space Marines, as a result of their upbringing in Cadia's martial culture. Their leader is the indomitable Lord Castellan Ursarkar E. Creed, the saviour of Cadia and hero of the 13th Black Crusade. Since Cadia is the capital world of the Cadian Sector and is often raided by various alien civilisations like the Eldar and Orks as well as the Forces of Chaos, the planet has been heavily fortified. All Cadians must serve at least a four-year-term in the military, and the amount of military presence on the world has lead to the civilian population becoming focused on weapons production. 71.75% of the Cadian population is under arms, either in the highly-skilled and very well-equipped Cadian Planetary Defence Force that is known as the Interior Guard or in the numerous Imperial Guard Regiments drawn from the planet's people. Chaos Space Marines from the Eye of Terror make frequent forays onto the surface of Cadia and must be hunted down. The bulk of the Cadian army is made up of the Shocktroops, with the remainder made up of the Whiteshields (conscript soldiers recruited at the age of 14 and trained to take place in Shocktroop regiments) and the elite Kasrkin soldiers. Cadian Regiments are consistently on average the most well-disciplined and most effective in the entire Imperial Guard. Because of its heavy concentration on military matters, Cadia's global economy is dominated by the manufacture of various weapons systems and exports vast numbers of weapons to its neighbouring Imperial planets, while importing very little other than food. Many other worlds use Cadian equipment to arm their own Imperial Guard Regiments, which explains how the Cadian Patterns of personal armour and infantry weapons have become the standard for the entire Guard.

Cadia has a special and honoured place in the history of Mankind. Cadia stands upon the edge of the Eye of Terror within a narrow corridor of stable space called the Cadian Gate. This forms the one and only predictable passage between the Chaos-infested daemon worlds of the Eye of Terror and Terra. It seems that although many Chaos fleets have ventured out of the Eye, very few Imperial fleets have ventured in. No battle fleet of any size can rely upon other stable passages from the Eye of Terror and they must pass through the Cadian Gate. Cadia is therefore one of the most strategically important planets of the galaxy.

On several occasions the Forces of Chaos have moved against Cadia and raging battles have been fought in the depths of space. Such huge battles are rare, but the constant intrusion of Chaos raiding craft is commonplace. Chaos Space Marines make frequent forays onto the surface of Cadia and must be hunted down. The bulk of the Cadian army is made up of the Shocktroops, with the remainder made up of the Whiteshields (conscript soldiers recruited at the age of 14 and trained to take place in Shocktroop regiments) and the elite Kasrkin Shock Troopers of the Imperial Guard.

Before the later Imperial colonisation of the 32nd Millennium, Cadia was the home of a lost fragment of humanity that worshiped the four Chaos Gods, probably since the onset of the Age of Strife. This society was encountered by the then-still-Loyal Word Bearers Legion 40 years before the outbreak of the Horus Heresy, and the prevalence of violet eyes amongst the populace was seen as a mark of mutation caused by the proximity of the Eye of Terror, which also appears violet in the visible light spectrum. This civilisation was eventually wiped out by the Loyalist forces of the Imperium following the end of the Horus Heresy with Cyclonic Missiles.

Cadia was then resettled by Imperial humans. The Cadian people today are naturally tall, fair-skinned, with blonde hair and blue or purple eyes. The fact that this new line of Cadians of untainted Imperial stock also sport violet eyes lends credence to the theory that the proximity of the Eye of Terror causes this mutation.

Cadian society is more martial than civilian, mostly due to the disproportionate ratio of soldiers to citizens in its population. The birth rate and the military recruitment rate are synonymous. Most Cadian children learn to field-strip a lasgun by the age of ten, and many young Cadians serve in the Imperial Guard as Whiteshields. Cadian society is so martial that camouflage patterns have made their way into the everyday fashion of even the wealthy and successful. It is very easy to determine who is an outsider or local on Cadia simply by what they wear.

Being a constantly embattled world, Cadia suffers numerous casualties in the defence of Cadia and the Imperium. Cemetery space on the planet is at a premium so the local priests of the Imperial Cult routinely check the grave markers of the honoured dead for legibility. When a section of a Cadian cemetery's grave markers are deemed illegible, those graves are exhumed and the bones are added to a communal pit. The Cadian belief is that once the names on a grave marker are illegible, the honours are forgotten.

Long ago Cadian cities changed from a plan of broad avenues to one where the streets of its cities were arranged in zig-zag patterns meant to make any intruding enemies fight for every block. At the heart of each Cadian city is a fortress called a Kasr in the local dialect of Low Gothic. The largest Kasr as of 241.M41 was Kasr Derth. Cadia's earliest Kasrs had been built in the High Terran Style, with the wide streets laid out on a grid system. Early in the 32nd Millennium soon after the planet's resettlement, during the first of the Black Crusades, most of the Cadian Kasrs were destroyed. The broad, ordered avenues of the Kasrs had proven impossible to hold or defend. Since then, the Kasrs have all been built in elaborate geometric patterns, the streets juking back and forth like the teeth of a key. From the air, Kasr Derth looked like an intricate angular puzzle. Given the Cadians' mettle and their skills at urban warfare, a Kasr could be held street by street, meter by meter, for months if not years.

Notable Cadian Imperial Guard Regiments

Many notable Imperial Guard Regiments have been drawn from Cadia, including:

• 7th Cadian Regiment, "The Lucky Sevens"
• 8th Cadian Regiment, "The Lord Castellan's Own" - The 8th Cadian was led personally by Lord Castellan Ursarkar E. Creed during the 13th Black Crusade
• 39th Cadian Regiment,"Xenobane"
• 69th Cadian Regiment, "The Fighting 69th"
• 81st Cadian Armoured Regiment, "Rolling Thunder"
• 89th Cadian Armoured Regiment, "Steel Lords"
• 110th Cadian Regiment, "Shadow Corps"
• 122nd Cadian Regiment - Distinguished themselves in the Vogen Campaign
• 412th Cadian Regiment - Featured in the PC game Dawn of War: Winter Assault where they carried out the Imperial assault against the Chaos Space Marine and Ork forces of the ice world of Lorn V
• 417th Cadian Regiment, "Hellbringers"
• 516th Cadian Regiment, "The Wildcats"

Sources

• Codex: Eye of Terror (3rd Edition)
• Codex: Imperial Guard (5th Edition)
• Codex: Chaos Space Marines (3rd Edition, Revised Codex)
• The First Heretic (Novel) by Aaron Dembski-Bowden
• The Eisenhorn Trilogy (Novel Series) by Dan Abnett