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.

Southern Theater Battles

First Legion's initial objectives fell in the southern reaches of the Parthorum Stream, a region roughly 50 light years in each dimension. Rogue Traders had already roughed out the shape of subsectors based on Asturus, Hucrov, Iuybos, Scomia, and Ublade, but during the Parthorum Xenocide First Legion's commanders referred to this vast area of space as the Southern Theater. The Osroene were aware of the limitations of their technology and relied on strong planetary defences to hold up invaders until one of their great fleets could arrive and decide the action. Adela Exard had obtained records of such relief actions against Gallvi raiders in popular histories and Hektor Cincinnatus drew up his plans accordingly. Rather than disperse his forces to planetary assaults and risk being defeated in detail, the Primarch's first target was the "Southern Fleet" that patrolled the region.

First Battle of Kopt Dara

Hektor dispersed the Rogue Traders under his command to monitor the systems of Southern Theater. As was usual practice, a Space Marine officer held 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 it was appropriate Adela Exard's Black Joke, now under the command of Markos Priscus, found the Xenos' Southern Fleet docked in the Destoona System at 057/811.M30. Priscus immediately ordered his Astropath to signal the First Legion's HQ that their quarry had been discovered. The arrival of Hektor Cincinnatus' naval force is timed to 073/811.M30.

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 effectiveness of Hektor's void tactics ruined such warm feelings. The Monarch of the Void, leading one of two Imperial columns, was the first vessel to come under fire at 094/811.M30. The First Legion's squadrons broke through the line of Osroene ships orbiting Kopt Dara. Two semi-connected melees ensued. The smaller, at the rear of the Osroene line 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. The action was over in less than a Terran hour. Following salvage and scuttling efforts, the Imperial fleet was underway again at 094/811.M30, moving out to jump points and then back through to warp to Sol. Only Black Joke remained in system, hiding behind the great bulk of Kopt Dara and monitoring the system via satellites.

Victory at Kopt Dara gave the Imperials a long 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 receive a request for reinforcements until months later, by which time events would have already overtaken their effort to respond. However, the damage incurred at the battle forced the First Legion to spend precious weeks travelling back to Mars to repair their warships. In order to expedite the process, Fabricator-General Kalkas Tygian personally commanded two Mechanicum warships, the Revelation of Victory and the Rites of War to take the place of the crippled First Legion cruisers Mount Ararat and Blessing of Thunder for the remainder of the campaign.

Imperial advance

Thanks to the efforts of the Mechanicum, the 3rd Expeditionary Fleet was ready to resume its offensive at 201/811.M30. Hektor split his command into three. His own Chrysaspides formed the reserve, while the First and Second Phalanxes, reinforced with substantial fleet assets, were detached to independent compliance operations.

Erasmus Sergius's First Phalanx launched a three-pronged campaign into the Hucrov subsector. By 293/811.M30 the lone planetary fortress at Hucrov-6 had fallen to Space Marines deployed by Thunderhawk and the planetary government capitulated rather than face annihilation at the guns of the Imperial fleet. Nearby Thucerus was better-defended and its orbital installations had to be reduced by First Legion's warships before occupation began, but again the defenders swiftly surrendered once their space defences were neutralised at 295/811.M30. Only at Xabradus did Sergius's men face sustained resistance. Here small teams of Space Marines were once again successful in disabling the planetary fortresses, but the ground defenders remained resolute. With reports of a substantial human population on-world, Strategos Bacchides Floridius felt unable to conduct a strategic bombardment and instead committed further ground forces to the surface. Floridius's naval support, in particular the sophisticated Rites of War did carry out tactical and operational bombardments, acting as orbital artillery for the Space Marines below. Xabradus was declared pacified at 303/811.M30 and handed over to a powerful garrison based around regiments of the Carlisian Shock Troops. Supply records indicate that the auxilia were still mopping up resistance for months to come, but the Adeptus Astartes were free to continue their conquests.

Second Phalanx, commanded by Lysimachos Fabius, were free to concentrate their efforts on the well-defended Scomia system. Like their battle brothers at Xabradus, the warriors of the Second were glad to have a Mechanicum warship with them. The advanced armament on the Revelation of Victory out-ranged the defenders' void weapons. Although Fabius was not prepared to engage in a lengthy stand-off engagement, Revelation of Victory badly damaged one of Scomia-2's orbital fortresses shortly after the void battle began at 292/811.M30. This good fortune allowed Space Marines to make surface and take out the planetary guns before the void battle drew to a close. The Imperial fleet finally disabled all three orbital installations and commenced landings in force at 294/811.M30. Osroene troops put up a spirited resistance but the thousands of Space Marines under Fabius's command harried them relentlessly, waging around-the-clock warfare that the Xenos were physically incapable of withstanding. Second Phalanx signaled at 317/811.M30 that organised resistance on Scomia-2 had ceased.

From the operations center deep within the Monarch of the Void, Hektor Cincinnatus monitored the progress of his forces. While pleased with the valour of his gene-sons, the Primarch was concerned that much of the time won at Kopt Dara had been expended securing just a handful of worlds. To speed up his Expeditionary Fleet, Hektor had his Astropaths signal Mars and request more warships from Kalkas Tygian, securing an agreement from the Fabricator-General to dispatch a squadron to the Destoona System. Hektor then directed his reserve forces to secure Destoona ahead of the Martian reinforcements. The Primarch's bodyguard and warships signaled their safe arrival through the warp at 331/811.M30 and began to move towards the inner system and the fortress world Jeglora. Black Joke remained in hiding behind Kopt Dara. While en-route, the Primarch received signals from First and Second Phalanx announcing the arrival of forces in the Asturus and Ublade subsectors. Hektor bade his Phalangiarchs to carry out their operations with all haste, even as the men under his direct command prepared for battle.

The limited voidship support available to the Chrysaspides made a gunnery duel with Jeglora's orbital stations a suicidal prospect. Rather than throw his voidships into a battle they could not win, Hektor relied on his finest warriors to carry the day themselves. At 370/811.M30, the Monarch of the Void launched a wave of boarding torpedoes to carry the Primarch and a few handfuls of his bodyguard to a station they knew only as Jeglora Orbital B. The station's primary hull was breached, but the torpedoes struck far from the small pressurised section. Although their position allowed the Chrysaspides to disembark peacefully, it also gave the Osroene security teams time to mobilise. Cassandor Honorius psychically signaled the Monarch of the Void that the situation was less than ideal but instructed the flagship to remain out of range and trust in Hektor. Such trust was well-placed. Disdaining the use of explosive charges, Hektor Cincinnatus tore open the first airlock the boarders sighted and led his men into the orbital's secondary hull. Many of the defenders died convulsing as their environment depressurised. Others, already wearing sealed encounter suits, held on to face the wrath of a Primarch and his chosen men. The skirmishes were never in doubt and within an hour of landing the First Legion teams had slaughtered the whole complement of the station. Such was the speed and fury of their assault that self-destruct protocols were not enacted.

Seizing Jeglora Orbital B had opened up a safe approach vector for the Imperial ships. Jeglora Orbitals A and C scrambled assault shuttles and hastily dispatched boarding teams to reclaim the fallen station, but Hektor was confident enough in his Chrysaspides to order the advance of the fleet. While the Primarch and his men held off Osroene warriors, Orion Mucius slipped his ships into planetary orbit. Superior torpedo designs allowed the Imperials to fire their munitions over the horizon and safely cripple Jeglora Orbital A, while the commander of the C station struck his colours before taking serious damage. Unaware of the slight Imperial forces above, the planetary government surrendered to Hektor without an Imperial soldier setting foot on Jeglora.

Second Battle of Kopt Dara

While the First Expeditionary Front of the Kondrus Aeroguard landed on Jeglora to carry out compliance actions, Hektor's squadron in orbit scuttled the planet's defence stations. The Primarch himself was busy in the operations center of the Monarch of the Void, taking in reports from the rest of the 3rd Expedition Fleet and issuing directives to the Legion headquarters on Luna. Confident that his offensive was gaining momentum, Hektor ordered the dispatch of additional Compliance Groups to provide garrisons in the wake of his Space Marines. The governors of Carlisar and Kondrus both signaled that fresh regiments would embark immediately, but were told that the transports should wait at jump points until provided with destination coordinates. Whether Hektor gave this order out of uncharacteristic caution or his trademark boldness was a subject of lengthy debate among analysts until the Parthorum Xenocide's campaign records were sealed to all but the most trusted Imperial agents.

It is certain, however, that Hektor was correct to urge his men to make all haste. An Osroene courier ship had reported news of the defeat at Kopt Dara weeks ago and the Xenos Empress Etuili Sevoold had ordered a massive counter-stroke. Half of the empire's remaining warships broke warp at Destoona at 418/811.M30, a force of more than fifty vessels. According to the legends of the First Legion, Logis Blessrad Dirz reported to Hektor that the Imperial squadron was now out-numbered six to one in ships and conceded even more in megatonnage. Dirz calculated a 0.68% chance of survival against the newly-arrived Osroene forces. The Primarch's famous response was, "Calculate the odds of victory instead!"

Logis Dirz's response went unrecorded, but it is unlikely that the tech priest shared his master's optimism. Regardless, the Master of the Void and her escorts got underway promptly, taking a vector away from the enemy fleet. Hektor and Navarch Isokratos Vivianus considered their options as the chase began. Attempting to change course and go cold was ruled out almost immediately. The Xenos warships were numerous and long-range scans had detected launch bays for attack craft capable of scouring the void for drifting vessels. Nor were there good prospects for escape. Despite the Osroene's primitiveness in interstellar travel and communications, their ships were handy in the void and would run down the Imperials before a jump could be safely made. Settling on the least bad of their options, the Navarch issued orders to his squadron to make for Kopt Dara while Hektor studied the gravity fluctuations around the gas giant in preparation for a battle there.

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 Basileus Orion Mucius
    • Rogue Trader Flotilla (Lord Captain Megasu Athon) - Syntagma Euthymios Varius
    • Rogue Trader Cruiser Black Joke (Captain Adela Exard) - Ouragos Markos Priscus
    • Rogue Trader Cruiser Hawk (Captain Hubert Fulton) - Ouragos Tecton Egnatius
    • Cruiser Rites of War - Magos Prime Arnav Davix
    • Cruiser Revelation of Victory - Magos Prime Aisaak Kamern
  • 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.