Battle of Taldoros

The Battle of Taldoros was an Imperial castigation campaign conducted by the newly incepted Dawn Guardians, a newly created Ultima Founding Space Marine Chapter comprised entirely of newly revealed Primaris Space Marines. This campaign was a part of the much larger Imperial Indomitus Crusade, to free thousands of besieged Imperial worlds from the clutches of the Ruinous Powers.

Background
Following the destruction of the vital fortress world of Cadia during the 13th Black Crusade, a massive tear in reality formed across the entire width of the known Galaxy. Known as the Great Rift, a large portion of the Imperium was cut off from the rest of the known galaxy. Inundated by madness, and assailed by neverending attacks by Chaos cultist uprisings, planetary-wide rebellions, encroaching xenos raiders, Chaos Warbands and daemonic legions, thousands of Imperial worlds were cut off - isolated and alone - and forced to defend themselves or be swallowed whole by the madness.

One such world was the besieged Imperial planet of Taldoros, which had been invaded by hordes of blood-maddened and berserk World Eaters Chaos Warbands and Khorne Daemonkin. Fortunately, the besieged world received help in the form of the Dawn Guardians Chapter to aid the war-torn planet. The fighting was brutal and bloody, in the extreme, with neither side giving no quarter. But eventually, the Dawn Guardians emerged victorious. Notably, 3rd Lieutenant Arvus Markius almost gave his life to single-handedly hold a gate against an entire horde of Khorne Berserkers for five hours until he was finally relieved. He survived his grievous wounds and ascended to become the Captain of the 3rd Company.