War of Nightmares

The War of Nightmares was a joint-Imperial defensive campaign carried out by the Star Wardens Space Marine Chapter and the forces of the Indomitus Crusade, to free the vitally important world of Vigilus from the grasp of the Forces of Chaos.

Background
With the arrival of Haarken Woldclaimer and his Black Legion forces, Ultramarines hero, Marneus Calgar, quickly assembled a force in an attempt to keep the coming Black Legion armada from landing on Vigilus. After hearing the report of the lone survivor from Strike Team Shadowspear, Calgar led the combined Imperial fleet towards the planet of Nemenghast to stall the Vengeful Spirit and the Chaos armada. Abaddon had his own plans however and as the Vengeful Spirit approached daemons materialized aboard the Imperial ships throwing them into disarray.

Aboard the Star Wardens flagship the bridge was assaulted by Slaaneshi daemons. In the ensuing battle, the Star Wardens lost more astartes than they had in the previous decade of war, including Captain Johan who was crippled and forced to be interred within a dreadnought. The Star Wardens quickly rallied however and slew the Chaos presence on their ships, launching a counterattack as the Imperial fleet retreated towards Vigilus. Back on the ground, First Captain Aldrich remained in Mortwald to help defend against the Iron Warriors, as the survivors from the void war returned to Hyperia to aid in clearing out the vast tunnel networks created by the Genestealer cults.

After another full decade of fighting Mortwald fell to the combined effects of the Iron Warriors siege and corruption from within the nobles of Mortwald. The Star Wardens forces consolidated inside Hyperia to join the Imperial's last stand upon Vigilus. It was then that Calgar's gambit paid off and Abaddon was forced to retreat along with a damaged Vengeful Spirit. Seeing hope, the Imperial rallied and began again to reclaim Vigilus, in order for that vital route through the Great Rift to remain viable.