Commanding the forces on the continent of Tuva was General Cunningham, a veteran of the Librian campaign and still in favour with the high command, despite the surrender of forces there. His experience against the Tau had put him in good stead for the coming battle and follwing the initial invasion he had dug in his troops in the hills and mountains of the border heights.
Knowing Raziel was likely distracted with other events, Cunningham decided to go on the offensive and attacked the mostly infantry based forces around Maybourne. Cunningham used his Leman Russ and recently acquired Manticore artillery vehicles to good effect, and the veterans of Melberg found that while the Chaos Marines were a stubborn foe, their firepower proved effective against them. Lacking armoured transports the battle became one of attrition, one the Night Lords realised they could not afford.