Parthorum Xenocide

This article is about a battle in the /tg/ Heresy project, a fan re-working of the Warhammer 40k universe.

Parthorum Xenocide
Date	811
Scale	sector-wide
Theatre	Parthorum Sector
Status	Decisive Imperial Victory
Belligerents
Imperium of Mankind	Osroene Empire
Commanders and Leaders
Hektor Cincinnatus	Empress Etuili Sevoold
Strength
3rd Expedition Fleet	armed forces of the Osroene Empire
Losses
Outcome
Parthorum Stream secured for Imperial shipping

The Parthorum Xenocide was the Imperium's name for the first of its three wars for the worlds of the Parthorum Sector. Only one Osroene-authored history of the conflict exists, in the little-read annals of the Pretender Sevtal Sevoold. Sevoold refers to this conflict as the Cataclysm, for the coming of the Imperium heralded the destruction of his people.

Background

The Parthorum Sector is defined by a long, stable current in the Warp beginning about 30 light years north of Terra and tracing a path north-west. This phenomenon, known as the Parthorum Stream covers a region roughly 250 light years long and 50 light years wide at its median point. Warp travel within the Parthorum Stream is relatively predictable and safe, and in the hundred centuries since its reconquest in the Great Scouring, only a handful of ships have been lost while in transit.

Osroene Empire

The Parthorum Xenocide destroyed Osroene centers of learning and killed the great majority of that race's scholars. Human savants only became interested in the history of the lost Empire long after its annihilation and have struggled to piece together its chronology. It is clear, however, that the realm was long-lived and stable, and judging by the anti-Imperial revolts after the war the Osroene must have been accomplished in the art of ruling over a multi-species Empire. Although the Xenos were not as advanced as the young Imperium, they possessed the Warp Drive and had used it successfully in the tranquil conditions of the Parthorum Stream.

The Imperium

Due to the limitations of calculated jumps through the Warp, the first decade of Imperial campaigns following the Unification Wars created a fairly small interstellar state centered on Sol. The Emperor's construction of the Astronomican on Terra increased the practical Warp jump distance one hundred fold and allowed the Imperium's Great Crusade to reach vast territories, among them the Parthorum Stream. Rogue Traders were quick to move into the area and investigate.

The Imperium had known about the Parthorum Sector for months before Hektor Cincinnatus was finally granted permission to launch a campaign of conquest. Although the Primarch was perhaps the third-most powerful of the Imperium's warlords, after the Emperor and Malcador the Sigilite, he had faced considerable opposition to his plans among the Terran adepts of the War Council. Ever confident, Hektor had begun planning while the matter was still in dispute, drawing on the reports of Rogue Traders Militant. Adela Exard's navigational and cultural records were of particular value, so much so that Exard and her Cruiser Black Joke were among the Rogue Trader forces hired on to augment First Legion during the campaign.

Battle of Kopt Dara

Hektor dispersed the Rogue Traders under his command to monitor Osroene space. As was usual practice, a Space Marine officer took formal command of each vessel, but the ship's original captain took the role of ship's master and guaranteed its smooth running. The sight of Solar-built vessels raised little alarm among the Xenos, who had become accustomed to the presence of Rogue Traders during the preceding months. But despite their innocent appearance, the Imperial vessels were hunting for concentrations of Osroene naval power. Perhaps appropriately, it was Adela Exard's Black Joke, now under the command of Markos Priscus, that found the Xenos' "Southern Fleet" docked in the Destoona System. Priscus immediately ordered his Astropath to signal the First Legion's HQ that their quarry had been discovered. Hektor Cincinnatus's naval force arrived in the Destoona System sixteen days later.

If the presence of the Black Joke had not aroused suspicion, the Osroene reacted promptly to the arrival of First Legion's warships. The Southern Fleet made haste for the outer planets of the Destoona System, taking up station at the gas giant Kopt Dara. From this position, the Osroene believed themselves well-sited to plot intercept courses against the invaders. It was a pleasant surprise for the Xenos that their enemies were willing to meet them at Kopt Dara, but the boldness of Hektor's void tactics ruined such warm feelings. The First Legion's vessels broke up the Osroene's lines and created two semi-connected melees, one of which was quickly won by a superior Imperial force led by Orion Mucius. The second, larger part of the battle centered on the two flagships and raged for longer, but the arrival of Orion Mucius's forces tipped the battle in favour of the Imperials.

Victory at Kopt Dara gave the Imperials a brief period of free reign through the southern portion of the Parthorum Stream. Although the Osroene had more warships to reinforce the weakened subsector, their high command would not learn of the battle for months and their ships, once dispatched, faced a long journey of short calculated jumps.

Imperial Order of Battle

For the outset of the campaign, Hektor had expanded his 3rd Expedition Fleet with the vessels and flotillas of several Rogue Traders Militant. The precise make-up of the forces under command of these idiosyncratic leaders is in doubt and the limited records available often contradict one another. The order of battle described below is therefore somewhat speculative.

• 3rd Expedition Fleet - Primarch Hektor Cincinnatus
  • Naval Task Force - Navarch Orion Mucius
    • Flotilla of Lord Captain Megasu Athon - Syntagma Euthymios Varius
    • Cruiser Black Joke - Ouragos Markos Priscus
  • Chrysaspides - Strategos Hephaestion Horatius
  • 1st Phalanx - Phalangiarch Erasmos Sergius
  • 2nd Phalanx - Phalangiarch Lysimachos Fabius
  • Various Auxilia formations drawn from the Solar Auxilia and The Carlisian Shock Troops.