By 2010.009M4 General Percival had heard about the disasterous fleet action in the Alphe system. Fortunately for the Imperium the Space Wolves chapter of the Adeptus Astartes had managed to slip a company past the Chaos blockade of the system, and their presence made an immediate difference, as Catechism forces were once again removed from the region of Pryford Meadows, with the marines reaching Barren Bay after only two days of fighting. It seemed the Catechism had reduced their forces in the south, which could only mean one thing, a new offensive.

The new offensive began swiftly on 1910.009M42 with the employment of the Catechism's most elite astartes formations. These forces crashed into the poorly equipped Alphean PDF units defending Erishore, but Percival realised he was unable to send Librian or Astartes units to their aid, as these were all tied up on other areas of the front, and the Corellian Storm Guard were still recovering from their mauling at the hands of the Night Lords. In the end, the Porphyrian 17th regiment was thrown into the breach, but lacking in the experience of fighting the Catechism they were handled badly, and soon it became clear Erishore could not be rescued. On 2310.009M42 the whole of Oldmere Island was abandonned, and the Catechism arrived on Hulme Island soon after, joining up with their Chaos allies in the north. By now the Imperium had lost control of more than half of the planet's major settlement, and tacticae calculated the planet would fall under Chaos control in less than six months.