With chaos losing on all fronts in the Perseus Deeps, especially in the systems closest to the Vastrid subsector, Admiral Thok decided to send a task force to aid his beleagured sometime ally on Bastien. A large force of cruisers along with the recently refitted battleship Mjolnir was sent to Bastien, via the Perseus run. Between Ares and Aethor however a force of Imperial warships commanded by Commodore Rawlings aboard the armageddon class Valiant was detected shadowing Thok's force. Thok immediately detatched the cruisers Rheintochter and Hyrrokin, along with two other cruisers, and these engaged the Imperial task force in deep space.
Rawlings, commanding Valiant, along with the jovian class Bulwark, tyrant class Centurion and dauntless class Firedrake, headed for the chaos force, keeping the under-armed carrier to the rear while attempting to bring the chaos fleet into battle on favourable terms. The commander of the chaos fleet however was very canny, keeping his fleet together in tight formation after realising the Imperial force had no nova cannons, and fighting abeam, firing lances from long distance and launching fighters to protect his fleet from torpedo attacks.
By keeping the Imperial fleet at arms length the chaos commander turned the battle into one of broadsides, something that at long ranges the Imperium could not win. The combined firepower of two devastations, a carnage and an Acheron battlecruiser was too much for the Imperial cruisers, as the Firedrake, unable to get into range before coming under concerted attack from the chaos escorts, was hulked early on. The chaos commander then concentrated his firepower against the Valiant, and when she was crippled Rawlings was forced to disengage his force or risk annihilation. Three chaos escorts were destroyed but the chaos cruisers suffered only minor damage. Worse still, the bulk of Thok’s force was now on course to intercept Admiral Dreyer’s battlegroup around Bastien.
It now seemed that deliverance was about to come for the defenders of Bastien, and Admiral Thok must have gloried in the idea of his position as the saviour of the Claws of Lorek. Even though Dreyers force outnumbered his own, they would have to protect the invasion force and would not be able to manoeuvre effectively. Just as he prepared to exit the warp near Bastien, he was alarmed to receive reports of a large Tau fleet in the vicinity.
The Tau had somehow managed to slip a battlefleet of three explorer class and two hero class capital ships past both the Imperium and the chaos augurs, no doubt due either to Tau stealth technology or their lack of psykers. Suddenly Thok was forced to break warp (not even the Grand Admiral was mad enough to accept battle in the immaterium) and face a fleet of equivalent size.
Battle was joined with the Tau battlefleet maintaining close cohesion. Even so the Grand Admiral was able to get his fleet into a good position, but crucially, fatally, the order to fire was delayed as uncertainty about the exact range to the enemy caused Thok to hesitate. He was swiftly punished. Finding their range with precision using their messenger class escorts, a massive barrage of railgun and ion cannon fire ripped into Thok’s vessels. Minutes later the mantas arrived and after scant minutes the chaos fleet was badly mauled. Although Thok did manage to destroy one of the Tau capital ships, the chaos fleet suffered worse. Two cruisers exploded and the veteran Queen Hel was crippled. Angry and frustrated Thok fled, leading his vessels back into the warp and back to Mordecai, the Tau having ruined any chance in his becoming the saviour of chaos.