Rogum Ardentem

The Rogun Ardentem was an Imperial defensive campaign fought by the Argent Leviathans in the defence of the vitally important Norian Sub-Sector against a massive Chaos invasion led by the Greater Daemon of the Pleasure God Slaanesh, the Keeper of Secrets known as Vro'nan Pyredancer.

History
As Daemonic incursions became more frequent, the companies left within the Dark Imperium attempted to defend the Norian Sub-sector were slowly pushed back to their Homeworld of Caerule. After being chased through the Sub Sector b the Greater Daemon of Slaanesh Vro'nan Pyredancer the companies gathered the civilians to make their final stand.

Led by 6th Princeps Kor'bhan Octarius, the Astartes began to prepare their defence for the inevitable attack on the planet. The small number of forces left on the planet managed to hold off the daemon onslaught before Octarius decided to evacuate all civilians and some Astartes onto whatever spacecraft they had left on the planet. After a large amount of debate about the Astartes leaving, Octarius managed to convince the 4th, 7th and 9th Princeps to evacuate what little forces they had left of their companies onto the ships. While the Astartes were evacuating civilians, the 6th Company began to hold off the daemon forces, coming face to face with the leader of the horde, Vro'nan Pyredancer, Greater Daemon of Slaanesh.

After the evacuations were completed, the 6th company alone managed to hold off the Daemons for another 6 days before being eradicated. The final survivor what Octarius himself who was subsequently burned alive by the Greater Daemon. The evacuees eventually came into contact with Roboute Guilliman's Indomitus Crusade and were brought back to the rest of their chapter.

With the 6th Company entirely wiped out, the chapter command begrudgingly accepted the offer of Primaris reinforcements, turning the 6th company into an entirely Primaris force.