Rogue Trader: Welcome to the Acheron sector

Our Rogue Trader campaign, which started back in 2014, is still going on; we've spun it off into Warhammer 40,000 and are looking to recruit some new people, so I thought it would be high time to expand on the fairly meager bit of fluff I gave to our players so long ago. First, I'd like to introduce our setting: the Acheron sector.

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The Acheron sector lies far to the galactic north, in Segmentum Obscurus. In the 37th millenium, what is now the Acheron sector was the northernmost fringe of the Charon sector, one of the most remote reaches of Segmentum Obscurus. During the Age of Apostasy, the Charon fringe was barely under Imperial control. Its rulers were an immensely rich and corrupt noble family, who nominally accepted the authority of Holy Terra. Xenos pirates raided the Charon sector, while the lords of the fringes claimed to be powerless to stop them.

After the death of the tyrant Vandire brought the Age of Apostasy to a close in M37, Saint Isabella the Just turned her attention to the Charon fringe. One of the leaders of the newly founded Adepta Sororitas, Saint Isabella had been a junior leader in some of the first wars of the Age of Redemption, and now set out on a crusade of her own to rid the Charon sector of the alien menace.

When Saint Isabella arrived in the Charon fringe, it quickly became obvious that the local nobility was in league with the xenos and had in fact repudiated the authority of the Emperor. Saint Isabella's crusade exterminated both the xenos and the corrupt nobles utterly. The name of the ruling family of the Charon fringe was expunged from Imperial records, and a new sector was founded: the Acheron sector. Saint Isabella appointed one of her most loyal generals, Lady Devanshi Indriani, the first proconsul of the new sector. House Indriani has ruled the sector ever since.


The Acheron sector is officially defined as extending from the border of the Charon sector all the way into the halo stars and to the northern edge of the galaxy. In the first millenium of its settlement, expansion northward was practically restricted to the area south of the Acheron Typhoon: present-day Prima, Secunda and Tertia Pars of the sector. The Typhoon is a permanent warp storm, and navigating around it is very hazardous. On both its eastern and western sides lie large gulfs of what navigators call null-space: areas of space where warp travel is almost impossible. The phenomenon that causes this is unknown, but in null-space astropathic communication is cripplingly difficult and the Astronomican is imperceptible. These two gulfs, Lacuna Phlegethon to the west and Lacuna Cocytus to the east, cut off the outer parts of the sector almost completely.

This changed in M38, when the revered Saint Anastasia came to the Acheron sector. Driven by a vision from the Emperor, Saint Anastasia and navigator house Radha forged a path around the Acheron Typhoon and mounted a crusade against the xenos empire beyond. Saint Anastasia led her troops through battles so terrible that most chronicles simply refuse to speak of them, merely stating that Saint Anastasia vanquished the xenos. She led the crusade as far as the Anastasian Depths, named in her honor. Her consort, Saint Valeria, crossed the Depths to the west to eliminate a last xenos stronghold on the dead world Silentium. In a horrible battle beneath the planet's surface, the missionary Saint Electra was martyred, and the xenos were eradicated.

Saint Anastasia's conquests were consolidated as Ultra Pars of the Acheron sector. Vestigium Hanini is officially the southernmost system of Ultra Pars, and the start of the twin routes past the Acheron Typhoon known as the Holy Gates. The Holy Gates converge at Babylonia Typhonis, seat of the procurator of Ultra Pars and gateway to the northernmost reaches of the sector.

North of Babylonia Typhonis, a stable warp route leads to the Quattor Proci Benitahi, a group of four solar systems close to each other that includes the hive world Augereau and the forge world Oecus Centrifugo. In M41, Rogue Trader Laurenz Frunze blazed a new route to the east, where the House Frunze colony Sacrificatio Imperatori now stands. North of the Quattor Proci is an area of dense null-space known as the Desolatio Thanos, which is considered completely unnavigable.

From Quattor Proci Benitahi, ships bound west for the Phlegethon sector travel to the garden world of Lilium, famed for its brandy. From Lilium they must attempt the Valerian Gates via Sermones Saryoni, Nekromanteion and dread Silentium. The northern route passes by the mining world of Lapis Nova to Ignis and Fides, where the Weyland Transit leads to Clavis Coronae and beyond. It's possible to take either of these routes and make a circuit around the Anastasian Depths to Sancrist, a colony of Rogue Trader house Karanja and chief Imperial world beyond the Depths. There is also a direct route over the Depths, the Pons Separatoris from the shrine world Termina Anastasiae to Dos Umbrae, but only House Radha hold the secret to navigating it safely. Occasionally, a bold Navigator makes the attempt; it invariably ends badly for them.


Beyond the Anastasian Depths lies the uncharted expanse of Ultra Pars. West of Sancrist are the Acheron Badlands, a seemingly limitless area punctuated by patches of null-space. To the north is a human civilization that calls itself the Confederation; they maintain a lively trade as middle-men between Imperial merchants at Sancrist and unknown operators on the other side of the Cortina Noctis. To the east of the Confederation lie the Morbid Reaches, where few Imperial ships dare pass. Somewhere to the northwest are the homeworlds of the Ishi xenos, a fierce, predatory race whose raids sometimes extend into Tertia Pars.

It's rumored that there are stable routes across the Cortina Noctis in the Morbid Reaches, and somehow the Confederation traffic across it. What lies beyond the Cortina Noctis? Who knows! All the ancient stellar catalogues can reveal is names for regions and occasional individual stars; nothing else. Most star systems in Ultra Pars are known only by their stellar catalogue numbers: for example, O.Ac.U.2887; the O designates Segmentum Obscurus, Ac is short for the Acheron sector and U for Ultra Pars. The brightest stars are generally numbered first; Babylonia Typhonis, a blue giant, is O.Ac.U.1. Beyond that, to the Imperial explorer most systems in Ultra Pars are a meaningless number on a chart. The only way to find out what secrets they hold is to go and look...

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It's out here, in the unexplored depths of Ultra Pars, that Rogue Traders go to seek their fortunes, and it's here that our campaign is set. Later, I'll write a bit about some recent events, and introduce our Rogue Trader house.