Sevastus Acheran

Sevastus Acheran is the current Captain of the Ultramarines 2nd Company. Acheran originally served under the command of the 2nd Company's long-time commander, Cato Sicarius.

But Sicarius was lost in the Warp with the birth of the Great Rift while returning to Macragge from Terra with Fleet Avenger. Sicarius had accompanied Roboute Guilliman to see the Emperor during the Terran Crusade and was now returning with the gift of the first Primaris Space Marines to the Ultramarines.

With Sicarius missing, Acheran was assigned to serve as his replacement.

Nemendghast Raid
In his new position, Acheran's first major operation was to lead a force of Vanguard Space Marines drawn from the 2nd Company designated "Strike Force Shadowspear" in a reconnaissance in force to the Industrial World of Nemendghast in the Vigilus System.

Nemendghast was a crucial supplier of war material to its neighboring world of Vigilus, which had come under assault by xenos and Chaos forces early in the Era Indomitus during the conflict remembered as the War of Beasts. Chapter Master Marneus Calgar and the Ultramarines were now leading the defence of Vigilus, and Calgar despatched Strike Force Shadowspear aboard the Strike Cruiser Carpatia to investigate the curious silence of Nemendghast.

Upon arriving at Nemendghast, augur scans revealed that the planet's industry was not only intact but now producing Daemon Engines and Possessed Chaos Space Marines at a rapid rate. It soon became apparent that the world had fallen to the control of the Black Legion in preparation for Abaddon the Despoiler's coming assault on Vigilus itself.

Knowing that the orbiting Black Legion warships would soon detect the Carpatia, Acheran ordered an immediate Drop Pod assault onto the planet's surface. Upon seeing the Chaos forces that had now claimed the world, Acheran knew that Nemendghast could not be liberated with the forces he had on hand and instead he sought to foil the Black Legion's plans by destroying its Daemonic Forges.

Though vastly outnumbered by the Heretic Astartes forces, Acheran refused to withdraw and targeted the Forge Infernus of Golbrecht Hive. With the aid of the Librarian Maltis' psychic abilities, the Vanguard Marines were able to infiltrate the heart of Forge Infernus, bypassing the various Black Legion patrols.

Acheran then split his forces into multiple small, fast-moving detachments, assigning them to missions of sabotage and assassination. He prioritised the destruction of not only the infernal machinery used to draw on the power of the Warp, but also the assassination of the Warpsmiths who maintained and operated it.

Explosions soon rippled throughout the Forge Infernus before the Chaos forces even knew they were under assault. Desperately holding back the maddening tide of the Warp, Maltis realized that if the eight pillars of binding above Forge Infernus' central spire used to draw daemons down into the hell forge could be destroyed, it would create a chain reaction that could bring down the entire complex.

Lieutenant Ulleus was given the task of drawing out the Black Legion defenders while Acheran saw to the destruction of the binding pillars.

Ulleus led squads of Vanguard Infiltrators into overlapping firing positions against Chaos Space Marine and Daemon Engine detachments that poured in to assail the Loyalist attackers. Ulleus and his warriors fought to the last, until a swarm of Venomcrawlers swept up from underneath to tear them limb from limb.

However this act of sacrifice bought Acheran the necessary time to launch separate attacks against each binding pillar. Each pillar was guarded by a pair of Obliterators, which Acheran countered with his Vanguard Suppressors. With the cover provided by the Suppressors' fire, Acheran led his Vanguard Infiltrators forward, pushing past the Chaos defenders and setting the charges on each pillar.

The Black Legion forces on Nemendghast were commanded by the Master of Possession Vorash Soulflayer, who at first suspected that a rival warband of Heretic Astartes had launched a raid on his world. However when the truth became clear, he personally led a vicious counterattack.

The assault was led by hulking Greater Possessed and Venomcrawlers that tore through the ranks of the lightly-armoured Infiltrators. In orbit, the Carpatia revealed that a Chaos fleet had detected the Loyalist strike force's presence and was converging on the Ultramarines' position.

This force consisted of not only Black Legion Heretic Astartes, but also allied Chaos Space Marines from the Crimson Slaughter warband.

Knowing that his force's survival was likely now impossible in the face of such odds, Acheran decided to make a final defensive stand and sell his and his Marines lives dearly.

But first he ordered Maltis to escape aboard the Carpatia and return to Vigilus to reveal to Calgar that Abaddon's invasion of Vigilus was imminent.

Maltis successfully made his escape just as Acheran was able to destroy the last pillar, and the entire Forge Infernus collapsed upon both the Heretics and the remaining Loyalist Astartes.

Plague Wars
Captain Acheran survived the action on Nemendghast and the War of Beasts to later take part in the defence of the Realm of Ultramar from the forces of the Plague God Nurgle during the Plague Wars.

Acheran led the 2nd Company to many victories over the Chaos forces assaulting Ultramar in the years before Roboute Guilliman returned home to Macragge following the end of the Indomitus Crusade.

But when Guilliman returned, he brought with him Cato Sicarius, who had survived his sojourn in the Warp and had been named as the commander of the Primarch's Victrix Guard.

It is unclear whether Acheran will continue to serve as the commander of the 2nd Company or whether Sicarius will be restored to his old position.