In 270911.M41, the Loyalist Gift of Fire task force was returning from its victory over the Astral Claws on the planet Shaprias in the Lamptan system, during which they had discovered the Astral Claws attempts to create thousands of additional Astartes using geneseed stolen from other Chapters. En route, they hit a warp storm and the Salamanders battle barge Pyre of Glory and the light cruiser Admiral Gregorius were damaged and forced to drop back into realspace. They were discovered by the Astral Claw strike cruiser Hyrcania, commanded by the infamous Arch-Centurion Carnac Commodus. The Astral Claw commander recognized that his ship could not defeat the two Loyalist vessels and sent a request for assistance.
The Hyrcania was soon joined by Phaeton’s Wrath, the flagship battle barge of the Executioners. They engaged the Loyalists, destroying the Admiral Gregorius and disabling the Pyre of Glory. At this point, Thulsa Kane offered the Salamanders terms for an honorable surrender, in which they would be escorted from the Badab system and must promise never to return. Pellas Mir’san, the captain in charge of the Salamanders, had fought alongside the Executioners when he was a Scout, and he knew them to be honorable warriors. He accepted the surrender terms, and the Executioners boarded the Pyre of Glory so that Thulsa Kane could personally accept his sword.
Arch-Centurion Commodus, enraged by the Astral Claws’ defeat in the Lamptan system, also boarded the Pyre of Glory. Due to the terms of the surrender, he and his Astral Claws were not challenged as they made their way to Salamanders’ gene-seed vaults. He intended not only to take the gene-seed the Salamanders had captured on Shaprias but also to take that belonging to the Salamanders themselves. When the Salamanders Apothecaries tried to prevent him from doing so, he slew them and ordered the Astral Claws to slaughter all of the prisoners.
At that moment, Thulsa Kane was accepting Pellas Mir’san’s surrender. As reports came in of the Astral Claws treacherous attack, Thulsa Kane became visibly enraged. Seeing this, Pellas Mir’san surmised that the Executioners were unaware of the full extent of the Astral Claws’ heresy. He told Thulsa Kane what he had discovered on Shaprias, and questioned the honor of the Executioners, both because of their alliance with such traitors and because they were allowing their terms of surrender to be broken.
Enraged, Thulsa Kane declared that the blood oath to the Astral Claws had been violated and that the Executioners’ honor could only be restored with the blood of the Astral Claws. The Executioners turned on their erstwhile allies, slaughtering every Astral Claw marine, serf, and servitor. Thulsa Kane presented Commodus’ head to Pellas Mir’san before the Executioners withdrew.