Percival was unaware however of the Death Guard's ambitions in the Hadron Expanse. Rather than simply aid the forces at Mordecai, Mortarion's children had decided to spreadh their forces widely to maximise the pressure - and plague - they could spread. It came as a complete surprise to Percival when in late 08.020M42 the garrison commander of Hobbiton reported an invasion by plague marines.
The Death Guard were supported by the fleets of Thok, not the Emerald Serpent, and Admiral Craddock was forced to withdraw. The Imperial Navy could not risk a space battle with so much of their strength supporting Kutuzov at Mordecai. The garrison was quickly overun but fortunately the Space Wolves were in the vicinity and organised their own counter offensive. The Wolves initially surprised the traitor astartes who had not been expecting such a response from the Imperium, but the stubborn and unnatural durability of the plague marines eventually carried them to victory, and the Space Wolf counter attack faltered. By the end of 08.020M42 much of Hobbiton had once again been overrun by chaos forces, and Percival was facing a war on two fronts, with limited resources.