[Stubber]

THE EXECUTIONERS’ BLOW
It looked as if the Chaos fleet would escape justice again, as the faster renegade vessels accelerated away from Ravensburg’s pursuit. Even as the enemy drew away, more drama was to occur, as an account by Captain Drew of the Fortitude described.
An armada of Eldar ships appeared from no where and attacked the Chaos fleet.
Caught between the attacking Eldar and Ravensburg’s fleet, the Chaos ships were annihilated, although a dozen more of the Emperor’s vessels were crippled or destroyed before victory was finally attained. Why the Eldar decided to lend their weight to the Imperial cause was never discovered, though it is a common belief that they had finally heard of Abaddon’s capture of the Blackstone Fortresses and had seen an alliance as their only chance of survival.

THE TIDE TURNS
As the news of Ravensburg’s great victory in the Battle of Gethsemane was spread throughout the fleet, even more promising tidings were to come. In the late months of 151.M41, the warp storms that had isolated the Gothic Sector began to abate and several ships from neighboring battlefleets arrived to reinforce the Lord Admiral’s bloodied fleets. The battle barges and strike cruisers of several Space Marine Chapters also arrived, bringing fresh, elite troops to the fighting. The Imperium’s solid defense, though broken in places, had prevented the Chaos fleets from achieving swift victory, and with the help of the Eldar and ships from nearby sectors, the Emperor’s servants could go on the offensive.

THE DESTRUCTION OF TARANTIS
Just as Ravensburg had never contemplated defeat, it seems that Abaddon was equally loath to give up what he had won. With two, possibly even three, Blackstone Fortresses under his command, it was Abaddon who was the greatest threat to Imperial worlds in the Gothic Sector. Just how much of a threat was not realized until the attack on the Tarantis system. On the edges of Gothic Sector, Tarantis was a common gathering ground for ships entering or leaving the region from Tamahl Sector and so it was here that Abaddon tried to stem the flow of reinforcements coming in.
His main fleet, accompanied by all three of the missing Blackstone Fortresses, swept aside the few Imperial ships close to where it broke from the warp. Closing rapidly into the system, the cruisers and battleships of the Chaos armada punched a hole through the defenders to allow the Blackstone Fortresses to break through. Countless millions of navy personnel and Imperial Guard died, planets were destroyed and an uncountable number of innocents perished as the two mighty fleets clashed, but what happened next was to totally eclipse all the horrific events of the war so far.
Combining their power together in the same fashion as at Fularis, the Blackstones unleashed a massive energy wave into the Tarantis star. With their objective complete, the Chaos ships conducted a fighting withdrawal and then jumped into warp space once more.
For a whole month, the Tarantis star raged and boiled. Tortured storms moved across its surface, its corona expanding to engulf the two nearest worlds. Any that could leave fled the system, but to evacuate the populations of three worlds was an impossible task. Four weeks after Abaddon’s attack, Tarantis’ star went nova, wiping out everything for many thousands of billions of miles in every direction in a storm of gas and plasma. Tarantis, a whole star system, was no more and Abaddon had the power to unleash this destruction wherever he wished.

THE TRAP IS SPRUNG
Lord Ravensburg firmly believed that Abaddon would try to capture the other three Blackstone Fortresses, but he had no idea against which of the three the Chaos Warmaster would strike next. The hunt continued for six months, with Imperial and Eldar ships patrolling through long forgotten systems in a desperate bid to find Abaddon and his horrific weapons. Then the forces opposing Chaos achieved a breakthrough – the Eldar had located Abaddon’s fleet in the Lower Lysades and were able to use their sophisticated ships to trail him through the warp.
From his course it was clear that the Warmaster was preparing to launch an attack on Schindlegeist, where Blackstone V floated in the depths of space. Leaving only a few vessels to deal with the other Chaos fleets, Ravensburg and the Eldar raced to reach Schindlegeist before Abaddon. Using ancient warp gates shown to them by the Eldar, the Imperial Admirals sped across the sector and arrived five days before Abaddon was due to reach the area. With a constant stream of information concerning Abaddon’s actions, the Imperial ships and Eldar lay in wait.
Outnumbered and caught by surprise, there was little the traitorous ship captains could do except die fighting. For three days the two mighty fleets battled, inflicting horrendous casualties on both sides. But for all their ferocity, the Chaos ships simply could not match the forces arranged against them. As the third day of fighting drew to its bloody conclusion, Abaddon once more broke the Blackstone Fortresses through the Imperial defense and headed towards the star. Ravensburg ordered all available ships to intercept them, though he knew there was little he could do to stop the behemoths. Only the Flame of Purity was close enough to attack, but the battlecruiser’s weapons had little effect against the huge stations.
As the Fortresses built up power for their cataclysmic attack, they were again linked by powerful energy beams. Seeing only one chance, Captain Abridal ordered all power to the shields and drove the Flame of Purity into the middle of the converging energy waves. The ship was destroyed almost instantly, scattered into its constituent atoms. However, the detonation had expended the Fortresses’ power and, as Abridal had hoped, the Blackstone Fortresses would take some time to accumulate the energy required for another attack. Luckily, time was something that Abaddon had run out of.

ABADDON’S DEFEAT
Their power systems drained, the Blackstone Fortresses could do little. Abaddon managed to escape into the warp with two of them, after a lengthy chase to the edges of the Schindlegeist system and a jump into warp space dangerously near to the gravity well. The Imperial fleet closed in on the third, unleashing all of their weapons, although still to little effect. Finally, two strike cruisers from the Angels of Redemption Space Marine Chapter, combined with assault boats from the Divine Right, boarded the isolated Blackstone in an attempt to recapture it.
Ensign Goldwyn was part of the Navy’s boarding party and he later reported to his superiors:
“We were astounded to find no crew aboard the
Blackstone Fortress. There was no opposition at all to
our boarding and on entering I found it entirely
unrecognizable from the base where I had been trained.
The walls themselves pulsed with energy, the surface of
which had become a deep-veined black – totally unlike
the harsh white-painted corridors and rooms I had
called home for six years. There was no sign at all of the
modifications made by the Tech-Priests, as if our
intrusion had been totally expunged. We had been
aboard for perhaps an hour when suddenly a high
pitched whine filled the air and the walls became ruddy
in colour. A sense of panic filled our hearts and we
hurried back to the Sharks [assault boats]. We were just
in time, as no sooner had we left than the Fortress
began to break up, slowly shattering into thousands of
fragments. It should have been a happy moment to see
our enemy destroyed but, although I cannot say why, my
heart was filled with sorrow and I could not get over the
feeling that something magnificent had died.”

At about the same time that the recaptured Blackstone destroyed itself, the other Fortresses across the Gothic Sector also self-destructed. Nobody knows if the Fortresses under Abaddon’s control destroyed themselves in a similar fashion: rumours have the Chaos Warmaster sighted both with and without the ancient engines of destruction. How or why the Blackstone Fortresses were obliterated remains a mystery.

Sources: Warhammer40000 rulebook, Battle Fleet Gothic rulebook