13th Black Crusade - Plague of Typhus: As the end of the 41st Millennium drew closer, the first signs that Abaddon's next long-feared assault was imminent came in the form of numerous sightings of drifting vessels emerging from the Warp in the sectors of Imperial space surrounding the Eye of Terror in the Segmentum Obscurus. The Astropathic station at Belisar Majoris was the first to report that it had detected a large number of Space Hulks approaching the outer reaches of the Belisar and Agripinaa Systems. The first indications were that the majority of these Hulks were uninhabited, but this turned out to be wrong. Estimates also placed these vessels converging on multiple vectors for the core planets of each sub-sector of the Agripinaa Sector. While the sheer number of Space Hulks suddenly emerging out of the Warp at this time was rare, it was not exceptional.In response to this alarming report, Marshal Helk, the commander-in-chief of the Imperial Guard's 2nd Army Group, ordered the deployment of additional troops aboard the 211st, 340th and 401st Naval Interdiction Squadrons, with a view to affecting boarding operations on those Hulks suspected of harbouring life. The Commissariat tripled attachment levels to these units, and all higher command ranks were informed of the possibility that these vessels might carry the taint of the Warp. The vessels of the Adeptus Astartes boarded those Hulks that they could, but their numbers were limited, as always. The Space Marines found these Hulks to be Chaos-twisted and disease-ridden nightmares, and subsequently, every such vessel encountered was destroyed with torpedoes and bombardment by Macrocannons, but for some it was already too late.In what could not have been a coincidence, outbreaks of virulent sickness erupted among many Imperial Navy starship crews within a day of a reported sighting of the dreaded Chaos starship Plagueclaw in the outer reaches of the Urthwart System by Captain Roark of the Dauntless-class Light Cruiser Duke Lurstophan. As the sickness spread throughout the region, Imperial naval forces and the number of starships fit for duty fell exponentially with the disease's progression, and then even more Space Hulks dropped out of the Warp, converging on vital strategic worlds.Ships from neighbouring sub-sectors rushed to destroy the Hulks and a small, ad hoc fleet was assembled at the vast orbital shipyards of the Dead World of Belis Corona in the sector of the same name under the command of the Imperial Navy's Admiral Quarren. The Imperial fleet surged from port and began the hunt for the Plagueclaw, though they were to encounter something far, far worse. In the shadow of the Frenerax Dust Cloud, the Imperial fleet was ambushed by a force of Chaos warships led by the Terminus Est, the flagship of the Herald of Nurgle, the Chaos Lord Typhus of the Death Guard Traitor Legion. The battle was short and bloody, with several Imperial warships crippled in the opening salvo of torpedoes, while others were overrun by vile, diseased creatures that vomited forth from the loathsome Chaos boarding craft. Admiral Quarren recovered well from his shock and rallied his forces superbly, counterattacking and fighting his way clear of the Chaos warfleet's trap. Typhus did not pursue and the majority of Quarren's fleet was able to limp back to port at Belis Corona. The Battle of Frenerax had been a costly disaster for the Imperium, but there was much worse to come.During the return journey to Belis Corona, thousands of Imperial Navy crewmen sickened and died and only with the help of system pilots was the Imperial fleet able to dock safely.But if the situation at Belis Corona was bad, it was worse elsewhere. Many of the Plague Hulks had slipped through the Imperial defensive net and the same contagion that had struck down the Imperial starships' crews was spreading like wildfire through many inhabited worlds in the Cadian and Agripinaa Sectors as well as those of the Belis Corona Sector. The Hive World of Subiaco Diablo proved to be an ideal breeding ground for the unknown plague and was quickly quarantined by officers from the Adeptus Administratum's Officio Medicae, but not before millions of people had already sickened and died. Within a solar month, a dozen other worlds reported cases of the same plague and panic spread throughout the Segmentum Obscuras as transit between neighbouring sectors was halted by the Imperial Navy in an attempt to stop further infection.As the epidemic spread, apocalyptic religious sects once more began to appear on every world afflicted with the disease, just as they had before the outbreak of the Gothic War, preaching that the Emperor's wrath had descended upon them and was a punishment for their sins of wickedness and vice. Only the truly faithful would be spared the Curse of Unbelief, as they named the plague, and hordes of flagellants filled the streets of every world adjacent to the Eye of Terror. The continued health of these fanatics in the face of the plague gave their words the sheen of truth and millions flocked to hear their extreme rhetoric out of fear for their lives. The plague continued to spread, but it was on Subiaco Diablo that the true horror of the disease was finally revealed. To the shock and disgust of the planet's inhabitants, the mass graves deep in the ash plains of the Hive World that contained the bodies of the afflicted heaved and split open and the corpses of those who had perished in the plague climbed up from the lime-encrusted ground. Soon millions of shambling corpses were advancing on the nearby hive city that they had once called home, clawing their way inside and attacking the already disease-weakened inhabitants.Within months, plague zombies were climbing from their graves on scores of worlds throughout the Segmentum's Belis Corona and Agripinaa Sectors and Imperial forces were stretched to their limits in containing these Chaos abominations as well as mobs of flagellating zealots who burned medicae ward facilities to the ground in their misguided attempts to stop the spread of the plague. Paralysed by the sheer scale of the zombie epidemic, the Imperial Navy forces in these regions were completely unprepared for the vast Chaos warfleet that emerged from the Warp at the edge of the Subiaco Diablo System and surged into Imperial space. The Herald of Nurgle, the Traveller, Typhus of the Death Guard, had come to reap the harvest of his plague of undeath and there was nothing to stand in his way as he claimed the world of Subiaco Diablo as the newest province in the Plague Lord's eternal kingdom of death.