Battles in the Perseus Deeps

In the Perseus Deeps the end of 10.013M42 saw another eldar assault on Ares, where Vassilevsky had deployed the Cerberex Guard in place of the Ultramarines in Ares city. Confident of their ability the imperial commander initially didn't worry too much when the eldar attacked once again, but their assault was determined and highly orchestrated. As the days wore on the Cerberex commander kept Vassilevsky updated, but the news wasn't good. The eldar firepower was too strong and for the fourth time the Imperium lost control of their capital. The eldar then took positions once more in Caeralon, the imperial army retreating to fixed defensive lines they had occupied only weeks before.

Elswhere in the Deeps a company of the Apocalypse Riders, en route to Ares, was unexpectedly ambushed by Dark eldar following its deployment on the world. Initially the eldar were thought to be part of the alliance and the new attack caused much concern, but imperial intelligence finally proved their worth, identifying the Xenos as the "Kabal of the Venom Drake", and not known as part of the Rillietan alliance.

The Apocalypse Riders however didn't care. They were aliens to be purged. As usual the riders responded to misfortune by aggressively going over to the attack, to the point of recklessness. Despite the raid having little strategic significance, the astartes company went "all in", charging the dark eldar lines at some risk, and sustaining heavier than necessary casualties. This headstrong recklessness drew criticism from imperial command and even the Ultramarines, who incurred the ire of the Rider's chapter master by pointedly suggesting pages in the codex astartes on deployment and tactics.

The Apocalypse Riders were once again saved by the bravery and tenacity of their land speeder pilots. They showed their skill on Ares against the dark eldar, using the terrain to evade incoming firepower while accounting for several enemy units and causing the aliens much distress. This display by just a handful of astartes allowed the remaining Riders to escape the raid, although the nearby supplies depot was completely ransacked by the Kabal.