While the Imperium were fixated on the war against the forces of chaos in the Perseus Deeps, and the emergence of dangerous forces in the Rifts of Hecate, General Percival's forces across the wider Hadron Expanse had been dangerously reduced. This necessarily meant Percival could not adequately defend all imperial holdings across the region, and he was forced to concentrate on holding Vanir, the Lysis system and Palantir. This did not go unnoticed by the Tau and during 022M42 they had already secured much of the far flung Tanis system, leaving the Imperium with a tenuous foothold on Tanis VII.

The guard regiment that held that inhospitable world came under assault in mid 09.022M42 with no strategic backup. Commander Malkaor's forces landed on the world and swept away all resistance, forcing the surrender of any remaining guardsmen who marched demoralised into Tau "re-education facilities".

Now the Tau had to make some decisions. the purpose of Tanis as an outpost had become almost worthless now the system of Lysis held no strategic significance with the closing of the Foramen Ignotum, a former pathway through the Cicatrix Maledictum, long gone ever since the Eldar had removed the necron device holding it open. Palantir however would be the obvious next move for the Tau in their aim to create the Hadron Expansion Sphere, but their expedition to the Rifts of Hecate had made them aware of the serious necron, tyranid and ork threat that could sweep across the Expanse if the Imperium were to be forced out of the region. The decision on how to proceed would need to be taken soon.