Battle of the Rangda System
The 51st Dark Angels Chapter, known as the Sable Griffons, had been stationed in the Rangda System since the Rangdan Xenocides. Eternally vigilant for the possible return of the Rangdan Xenos, the 1,500 warriors were met by the Sons of Horus Heavy Cruiser Conqueror's Pride which signaled it needed to resupply. Once in orbit, several squadrons of Stormbirds and Storm Eagles headed for the surface of Rangda, the former homeworld of the Xenos. Queries from the Dark Angels regarding their destination were ignored and when Knight-Praetor Kordray Mordred demanded to speak with the Sons of Horus commander, he was met with a sudden and indiscriminate barrage. The barrage left little of the Dark Angels fortifications intact yet inflicted only light damage on the chantry house of the Order of Broken Claws.
The outermost defenses crippled, the Sons of Horus gunships set down and disgorged a full Chapter including a company of Justaerin Terminators. The Sons of Horus advanced upon their shattered foe, committing only a token force to seize the Astropathic nexus. The Justaerin Consul himself tore the Chapter House gate from its hinges and dared the defenders within to come out against him. When none dared to come forth, the Justaerin marshalled their strength and entered the antechamber. At that moment, a great detonated spread across the entrance, causing great damage to the Sons of Horus and trapping them inside. It was then that the 12 surviving Dark Angels of the Order of the Broken Claw attacked the nearly 50 Justaerin. Within the pitch-black labyrinthine corridors of the Chapter House the Broken Claw broke the pride of the Warmaster and when Sons of Horus reinforcements managed to breach the rubble and arrive inside they found a mountain of their comrades corpses. The three surviving Dark Angels withdrew to the lower vaults where the relics of the Rangdan were held in stasis.
Their honor besmirched, the Sons of Horus refused to resort to simple solutions such as Promethium or Phosphex and instead selected the most skilled of their number to launch a direct attack. The first group consisted of veterans but only survived for ten minutes, felling a single Dark Angel defender. Three further bands of Sons of Horus descended and stilla single Dark Angel stood guard over the guard. Word then reached the rearguard that the Dark Angels survivors at the astropathic nexus had driven them from the core and had control of off-world communications. Finally, the Sons of Horus sent in their Destroyer Squads. The final Dark Angel gave a last salute before being consumed by Phosphex. The Sons of Horus Techmarines were able to scour the vault for valuable pieces of Rangdan technology, which had been their objective all along. The Conqueror's Pride subsequently launched a mass orbital bombardment to erase any trace of their attack. attack. One of the grounded Stormbirds was captured and the relics it bore lost to a daring assault by Knight-praetor Mordred and his Deathwing lifeguard, while another was shot down and destroyed by Ravenwing warriors piloting Xiphon Interceptors, though the survivors of the Sable Griffons could not halt the exodus of the Sons of Horus.
The remnants of the assault force reached orbit leaving the Dark Angels trapped below, but they could spare no time to exact any revenge, for the Promethean Class Cruiser Invidious had returned, called back from patrol by Knight-Praetor Mordred, and the Conqueror's Pride was no match for the ancient Terran warship in open battle. Bloodied in body and pride, the Sons of Horus fled the Rangda system. They had come seeking both weapons for Horus' desperate rebellion and to break the will of one of the unquestionably loyal Legions but could claim little more than a phrrhic victory.