Tyndareous Invasion: Lycaon Guard make landing but Sky Lords suffer embarrassing defeat

In the Zadoc subsector General Van Dorn was keen to build on the success of Hylas and start taking the war to the Imperium's enemies. With a fresh fleet, reinforcements from the Lycaon Guard and Sky Lords chapter of space marines, Van Dorn proposed a plan to attack the Tau, who effectively surrounded the Imperium's two worlds in the Mabb Nebula, blockading them from easy contact with Caitlen station and the Imperial bases in the Perseus Deeps.

The Sky Lords agreed, as Vorushko was keen to prevent the Aleph Expansion Sphere Tau enclave from overwhelming the Imperial bases and establishing contact with the Federacy and the rest of the Tau empire. In the Imperium Nihilus, there was no "crusade" and "loyalist" argument, as both forces were acting together as the Imperium of Mankind. Vorushko was keen however to prevent the situation arising where she had to expend forces defending her right flank from Xenos threats while prosecuting her more important goals against Hathek in the Foramen. Taking the fight to the enemy served this purpose well.

The plan was drawn up by mid 03.018M42, and a battlegroup supported by Admiral Dreyer's fleet left for the Tau holdings in the Mabb Nebula. The Tau world of Tyndareous would be invaded, while the Sky Lords conducted raids against tau infrastructure across the region of space.

The invasion of Tyndareous by the Lycaon went well. The tau were taken by surprise by the sudden appearance of an Imperial battlegroup and despite offering significant resistance, the Lycaon Guard were able to land and establish a perimeter in the mountainous terrain to the west of the inhabited zone. From there they pushed the front line forward, taking Ranier pass and the settlement of Burbeck bay, reaching the sea and cutting the Tau defences in two.

The Sky Lords however had more significant problems as they attempted to put a nearby Waystation out of action. The station, designated 233 by the Imperium, was protected by significant ground defences installed on the planet around which it orbitted. To strike the Waystation, these protective defences, including high powered railguns and a defence shield, would need to be put out of action.

The Sky Lords landed without incident, but the Tau had detected their landing and immediately took up defensive positions around their key installations. The Sky Lords advanced, causing significant damage and losses against their enemies, as the Tau found the heavily armoured land raider force difficult to deal with.

However, just as the fighting was reaching a climax and the result hung in the balance, an unfortunate event occurred. With a blinding flash the lead Sky Lords land raider detonated in an enormous fireball, throwing superheated metal and volatile chemicals over a wide area. The initial explosion crushed the Sky Lords' commander and lieutenant before the blast wave crashed into the ruins of a Tau installation. This proceeded to collapse, wiping out the Sky Lords' elite force of Stern Guard.

Amazingly the occupants of the Land Raider managed to crawl from the wreckage, but the dramatic spectacle had severely neutered the elite force, and the Tau counter attacked in force. Although the Sky Lords hung on for some time, the raid was a failure and the remaining astartes were forced to abandon the bodies of their fallen and evacuate the planet.

It is unclear how an astartes Land Raider could have exploded so spectacularly, and the Sky Lords are unlikely to ever comment on the matter. However the Tau noted that minutes before the detonation, a tech priest within the Sky Lords retinue was seen "fixing something" on the vehicle. The fact that this priest was not a true techmarine may have some link with the devastating mishap that cost the Sky Lords several of their finest warriors and doomed the raid on Waystation 233.