The Tau Offensive and the Destruction of West Hallen Defences on Hylas

In the waning weeks of 10.024M42, the fall of Finlay had left Imperial forces under General Van Dorn entrenched in the swampy regions of West Hallen, preparing for the expected Tau assault. However, the anticipated attack took an unexpected turn with the sudden arrival of Tau Commander Malkaor, whose forces had last been recorded operating within the Hadron Expanse. Rather than pursuing a typical campaign of territorial gain, Malkaor’s troops launched a targeted and systematic operation aimed solely at obliterating the Imperial trench lines and defensive fortifications across the West Hallen wetlands.

Malkaor’s strategy capitalised on the high mobility of Tau forces, which allowed his troops to strike at weak points in the Imperial defences before rapidly redeploying. Malkaor’s forces dismantled bunkers, shredded trench networks, and collapsed fortified emplacements across the boggy landscape, neutralising Van Dorn’s hard-won defensive line before the Imperial forces could adapt. The destruction of the defenses left Van Dorn’s troops dangerously exposed to further Alliance advances into Hylas’ strategic heartlands.

Aware of the threat posed by Malkaor’s mobilised campaign, the Grey Knights, who had tracked the Tau Commander to Hylas, launched a counter-attack against the Tau forces. With the blessing of the Ordo Malleus, they attempted to stop the Tau from stripping West Hallen of its critical fortifications, thus preserving Hylas’ defences for future offensives. Malkaor, however, leveraged the Tau’s superior mobility and advanced weaponry, decisively repelling the Grey Knights’ assault and inflicting heavy casualties on the elite Imperial forces. By early 0511.024M42, Malkaor’s victory was complete, and West Hallen’s fortifications lay in ruins.

Having effectively crippled the Imperial defences, Malkaor’s forces withdrew swiftly from Hylas, evading an encounter with Imperial naval assets stationed in orbit. His rapid redeployment and disappearance suggested an emerging strategy of mobilizing as a reserve force across the sector, striking at key positions before Imperial forces could marshal a counter-offensive.

For General Van Dorn, the destruction of West Hallen was a grim blow. Though the defences of East Hallen still offered some hope for resistance, the Imperium’s forces on Hylas faced a prolonged and increasingly precarious campaign. Van Dorn knew that while East Hallen’s fortifications remained formidable, the coming assault by the Alliance and the threat of Malkaor’s unpredictable manoeuvres would make holding Hylas a far more daunting prospect.