Nolan

Prior to the Schism
On the southern deep arm of the Sub-sector lies Nolan, sitting amid a nebula of various gasses. Nolan was once a core Forgeworld well known for its retained knowledge of Conversion Beamer technology. Sadly, at the turn of M41, a weapons test rendered a nearby world maiden world of Woad into a nuclear wasteland. The scandal saw so much censure that the Forgeworlds STC catalogue was reduced, though many great Manufactorum stand silent, awaiting the day they are dismantled and moved off world. That world destroyed was ever after referred to as Rust.

During the Schism.
On the ashen wastes of Nolan, in one of its rare copses of Acid Trees  and Fell bark, the machinations of Inquisitor Dormengast bore fruit of a kind. Giving direct orders to the Cadian 501st, the Inquisitor demanded a full strike against an unknown target. Despite concerns, the Imperial Guard did their duty.

It isn't clear who fired first. And the Incident at the Nell Discharging Flats would be argued about long after. What is clear is that the Black Scorpions were either prepared for the misguided attack, or that they had planned their own attack all along. What is also clear, is that the ensuing carnage spoke volumes of what the Space Marine chapter thought of the Imperial Guard's presence in the area: Hostile and unwanted.

The Black Scorpions slaughtered their way through several platoons and material and turned the Starport on Nolan into a carnal house. Inquisitor Dormenghast however, got what he wanted:  An Imperial Guard Regiment that was now bound to his service against these Renegades and enough material to further his ties with the remaining Adeptus Mechanicus on the planet. What this would mean, would not be known until later, though the 501st were desperate for revenge.