Mimir VII retaken by Tau forces

The war over Hexis and in the Persues Deeps was seen as largely irrelevant to the tau. Thanks to their alliance with the Kel Sandros Eldar, the tau had been kept largely oblivious to the wars over the necron devices, their Empire held together by the gift of the Foramen Ancilla from the Aeldari. The tau had suffered from the coming of the great rift, but still had plans to expand into the Hadron Expanse, with help from the Federacy.

Echo Reach had become the hub of Tau expansion, while Hussaria had become a warzone against the Imperium. The tau had successfully invaded the world but then a counter invasion by general Percival's forces put paid to any assumption that the Imperium would not fight for territory so far away from the strategically vital warzones. The Imperium would fight for every scrap of land.

Against chaos, the Emerald Serpent had a major base at Boltarean, and recognised the tau expansionism for the threat it was. Late in 019M42 they had invaded the outer worlds of the Mimir system, held by the Federacy, which had been countered and halted by intervention from the tau. Now the tau commander Malkaor finally had enough supplies to counter attack the chaos forces in the system, and landed on the besieged planet of Mimir VII, where the tau garrison had been holding out against the Emerald Serpent for months.

The attack by the newly arrived tau forces did not go as smoothly as they had wished, as the Emerald Serpent quickly sent in their elite forces to hold the tau attack. A brutal battle erupted in front of the single outpost on the otherwise cold dead world, with the tau forces coming under a brutal counter attack. After hours of savage fighting, somehow the tau invasion force held on, and as the Mimir star set on the battlescene, the chaos forces finally withdrew, preferring to continue the war at Mimir from a stronger position elsewhere. The death toll had been enormously high for such an unimportant dead world, but if the Mimir system was to be claimed by the tau, every chaos foothold would have to be systematically cleared. The cost of such operations would need to be reduced however, as this level of slaughter was considered unacceptable by Alliance high command.