The Agripinaa Sector of the Milky Way Galaxy is a sector of the Imperium of Man in the Segmentum Obscurus to the galactic north of Terra that is located near to the fallen Fortress World of Cadia. The Agripinaa Sector lies adjacent to the great Warp rift known as the Eye of Terror and was one of the locations where Abaddon the Despoiler's 13th Black Crusade was fought in 999.M41.
Though the Forces of Chaos were defeated by the Imperium during that conflict, it was a pyrrhic victory at best, as the world of Agripinaa did not weather the Chaos attacks well and much of its industrial infrastructure was laid ruin. Battlefleet Agripinaa fared no better, sustaining heavy losses during the brutal conflict. Typhus of the Death Guard Traitor Legion, the so-called "Herald of Nurgle," consolidated his grip upon the Ulthor System, claiming it as the capital of a nascent, plague-ridden empire of his own. It is apparent that the taint of Chaos is now well and truly upon the Agripinaa Sector.
The Agripinaa Sector is one of the closest Imperial sectors to the vitally important Fortress World of Cadia and the Cadian Gate, the only predictably stable Warp route that leads out of the Eye of Terror and into the realm of the Imperium. The Imperial Navy shipyards for the sector were located on the Forge World of Agripinaa. This world provided materials for the Cadian front, and its industrial heartland was solely engaged in the production of ammunition. As such, it was considered a valuable lynchpin in the defence of the Cadian Gate.
In 999.M41, war came without warning to the Agripinaa Sector, and the opening moves by the Forces of Chaos saw large numbers of plague-ridden Space Hulks entering Imperial space. Though many were intercepted by the Space Marines and destroyed, some managed to escape the Astartes' attention. Some of these foul vessels of contagion found their way into the Agripinaa Sector, spreading their disease and pestilence amongst the masses throughout the sector. Along with the adjacent Belis Corona Sector, they were some of the first to bear witness to the rise of hordes of infectious, undead zombies that threatened billions of people on many of the Imperial worlds within the sector. This plague was later named the Plague of Unbelief.
While the defence of the Cadian Gate from the Forces of Chaos continued to go badly upon the surface of many worlds in the Cadian System, in particular Saint Josmane's Hope and Solar Mariatus, the war in space was fought more on the Imperium's terms. The Cadian System had been the focus of Abaddon's primary fleet actions, and the Imperium's fortunes there changed from day to day. The situation was highly fluid and the Chaotic naval forces found themselves stretched to exploit the victories they had won.
A fleet the size of which has not been seen since the end of the Gothic War eight standard centuries earlier had been dispatched from Cypra Mundi, and arrived at Belis Corona in preparation for a massive Imperial counter-offensive into the Cadian Gate. The arrival of this vast armada allowed those Imperial vessels that had been fighting continuously since the beginning of the invasion a brief respite. Severely depleted ship’s companies were bolstered through indiscriminate press-ganging, and hasty repairs and refits were undertaken on those vessels most in need of them.
The Imperial reinforcements were split into battlegroups, each tasked with bolstering the defences in a specific sector of the Segmentum Obscurus. The regions around the Eye of Terror encompass many millions of cubic light years, and only by the concentrated application of resources in those areas in most desperate need could the Imperial Navy hope to make inroads and slow, stall, and eventually repel the Chaos warfleets plaguing the region. A small number of Imperial Navy ships won a decisive victory when they managed to hold back a larger Chaos Fleet at the Ilthirium Belt, buying time for Battlefleet Agripinaa to arrive and allow the remaining ships to retreat. This course of action however, left the Agripinaa Sector open to invasion and soon the worlds of this sector and the Belis Corona Sub-sector of the Belis Corona Sector were transformed into nightmarish realms of plague and pestilence.
As the full force of Abaddon's invasion hit the sector, one man, Regu Hane, was hailed as a saviour -- he led a bold counter-attack that succeeded in banishing a horde of Khornate Daemons, and would later be raised to the status of sainthood. Later the mysterious Eldar Harlequins intervened in the fighting, but the defenders were stymied when the notorious Dark Apostle of the Word Bearers Traitor Legion, Lord Erebus, caused the raging tempest of Warp Storm Baphomael to surge forth and engulf the outlying star systems of the sector.
It was only in the closing stages of the conflict that the Imperium was able to mount an effective defence against the raging hordes of the Ruinous Powers, when the combined forces of a number of Space Marine Chapters broke through the storms and fell upon the invaders with a righteous hatred born of 10,000 years of conflict. By the end of the war, the planets Albitern, Amistel, Lelithar, Malm's Reach, Ulthor and Yavor lay in ruins, and a number of other key systems of the Agripinaa Sector hung in the balance. Though Agripinaa itself still stands, without the Agri-Worlds of Yayor. Ulthor and Dentor. Its populace may yet starve to death, and without the vital materials provided by the Hive Worlds of Albitern, Amistel and Tabor, its mighty forges may yet fall silent. The so-called "Herald of Nurgle," Typhus of the Death Guard Traitor Legion, has claimed the now blasted world of Ulthor as his own realm, a stronghold beyond the Cadian Gate from which he can bring terror to the other worlds of the Imperium at his leisure. Nightmare visions of a thousand Astropaths tell of the birth of a new Daemon World within the domains of Man.
Further, unconfirmed reports state that one of the Blackstone Fortresses were destroyed by raiders of the Necrontyr off the shoulder of the Lustitia Belt. Senior members of the Ordo Xenos are en route to the area, and Deathwatch Strike Cruisers are already engaged in ensuring no vessels other than their own enter the area.
Imperial Control Rate: 82.7%, State: Faithful.
- Yaymar - Plasma vapour world, Designation: GG.6.58.001, Orbital Distance: 0.37AU, 0.16G, Temperature: 204C, Tithe Grade: Adeptus Non, Aestimare: VP679.
- Barant - Declining orbit, Designation H.318.104.22.168, Orbital Distance: 0.89AU, 3.8G, Temperature: 180C, Tithe Grade: Adeptus Non, Aestimare: OD196.
- Orax - Many raw iron deposits, Designation H.26.587.01, Orbital Distance: 1.23AU, 1.74G, Temperature: 28C, Tithe Grade: Exactis Particular, Aestimare: A350.
- Morten's Quay - Naval reserve depot, Designation R.2.58.01, Orbital Distance: 1.99AU, 1.45G, Temperature: 10C, Tithe Grade: Adeptus Non, Aestimare: MR758, Imperial Control Rate: 95.6, State: Faithful, Resistance: High, Conflict: High.
- Faith's Anchorage - An ice moon of Morten's Quay, which possesses a few Promethium mining facilities.
- Agripinaa - Civilised World. Almost the entire surface of this Forge World is covered in mines, factories, refineries and other industrial infrastructure. Agripinaa produces resources primarily for the defence of the Cadian Gate, like other star systems in the sector. Rumours of Harlequin activity. Four companies of the Blood Angels Space Marines assaulted the world of Agripinaa during the 13th Black Crusade, and they sought out the leader of the attacking forces, the notorious Chaos Champion of Khorne Kossolax the Foresworn and his World Eaters warband, the Foresworn. Much of Agripinaa's industrial infrastructure now lies in ruins as a result of this conflict. Designation AM23.5, Orbital Distance: 2.4AU, 0.7G, Temperature: 4C, Tithe Grade: Exactis Tertius, Aestimare: B30, Population: 80,000,000, Imperial Control Rate: 80%, State: Faithful, Resistance: Extreme, Conflict: High.
- Aurent - Naval waystation. A small group of Imperial warships retreated here after an attack on the Chaos warship Darkblood. 2 Designation S.2.12.0, Orbital Distance: 3.14AU, 2.46G, Temperature: 2C, Tithe Grade: Adeptus Non, Aestimare: MS54, Imperial Control Rate: 97.2%, State: Faithful, Resistance: High, Conflict: High.
- Chaeros - Designation E.00.25, Orbital Distance: 3.97AU, 8.17G, Temperature: 0C, Tithe Grade: Adeptus Non, Aestimare: D29.1. Chaeros was renamed New Cadia following the destruction of the Fortress World of Cadia by Abaddon the Despoiler during the 13th Black Crusade when many of the survivors of that lost world came to settle in the nearby Agripinaa System and chose frigid Chaeros as their new home.
- Urath - Death World. Waste planet with elliptical orbit, Designation W1.0.11, Orbital Distance: 9.45-10.23AU, 1.62G, Temperature: -7C, Tithe Grade: Adeptus Non, Aestimare: GP764.
- Narsine - Hive World. Source of Agrapinaa labour, Designation H.25.87.0, Orbital Distance: 11.76AU, 1.43G, Temperature: -100C, Tithe Grade: Adeptus Non, Aestimare: A36, Imperial Control Rate: 68.9%, State: Dependable, Resistance: Extreme, Conflict: High.
Imperial Control Rate: 14%, State: Anarchy, Resistance: Moderate, Conflict: High.
Attacked by an unknown raiding force and population discovered butchered like livestock similar to what happened at Dentor (see below).
- Amistel Majoris - Plague Marines of the Death Guard Traitor Legion landed and decimated the Imperial defence forces until the Imperial Guard troops of the Drookian Fenguard arrived to bolster the beleaguered defences. The planet was reduced to a pestilent necropolis of decaying corpses. However, the Imperial defence proved masterful, allowing Imperial forces to survive until the arrival of the Howling Griffons and the 1st Company of the Iron Knights Space Marine Chapters and Titans from the Legio Astorum. The conflict then devolved into protracted, brutal trench warfare. Imperial Control Rate: 14%, State: Anarchy, Resistance: Moderate, Conflict: High.
Provides the Bar-el Penal Legions for the Imperial Guard. Imperial Control Rate: 39.9%, State: Unreliable, Resistance: High, Conflict: High.
- Dentor - Attacked by an unknown raiding force and population discovered butchered like livestock. Imperial Control Rate: 20.3%, State: Unreliable, Resistance: Low, Conflict: High.
- Finreht - Provides the Finreht Highlanders regiments for the Imperial Guard. Imperial Control Rate: 33.3%, State: Unreliable, Resistance: Moderate, Conflict: High.
- Lelithar - Imperial control broke down and mob rule was instated when hit by Curse of Unbelief. Jouran Dragoons and Legio Ignatum landed here to retake the planet. Supported by Death Spectres Space Marines. Imperial Control Rate: 0.4%, State: Anarchy, Resistance: Moderate, Conflict: High.
- Malin's Reach - Imperial control broke down as mob rule was instituted when plagued by the Curse of Unbelief. Attacked by a large Word Bearers Traitor Legion waband led by the Dark Apostle Erebus. Population discovered butchered like livestock after discovery of similar event on Sarlax. Though a great many of the Imperium's forces present on the world were lost, along with the greater part of the capital city, it was considered a merciful end for them. 31st Destroyer Squadron operating out of Demios Binary destroyed by unknown ambushers, probably Chaos Space Marines, blue and gold armour reported. Imperial Control Rate: 0%, State: Anarchy, Resistance: N/A, Conflict: High.
- Sarlax - Attacked by an unknown raiding force and population discovered butchered like livestock after the discovery of similar event on Dentor.
- Tabor - Hive World. Imperial Control Rate: 26.9%, State: Unreliable, Resistance: Moderate, Conflict: High.
- Ulthor - Imperial Control Rate: 0.4%, State: Anarchy, Resistance: Low, Conflict: High.
- Yayor - Imperial Control Rate: 12.4%, State: Anarchy, Resistance: Moderate, Conflict: High.
- Codex: Eye of Terror (3rd Edition), pg. 25
- The Thirteenth Black Crusade (Background Book) by Andy Hoare
- Warhammer 40,000: Rulebook (8th Edition), "The Fall of Cadia," pg. 161
- Cadia Stands (Novel) by Justin D. Hill, Part Four, Chs. 3, 4, 8
- 13th Black Crusade Worldwide Campaign - Eye of Terror Newsletter, "Death By a Thousand Cuts"