Red Dawn

The Red Dawn is a notable campaign of the Indomitus Crusade carried out by the Penitent Knights against a reawakened, unknown Necron Dynasty led by Necron Lord Luxthoris the Granted. This involved the defence of the vitally important Imperial world of Galadhor against the predations of the vile undead, metallic xenos.

History
After many years of relative uneventful and relative peace on Lor'dra, a new threat emerged from the red plains. Untold millions of Necrons emerged from their tombs under the command of the Necron Lord Luxthoris, the Granted. This unliving scourge destroyed all in its path and massed for a siege on Galadhor. The Orders of the Lightbound and Cleansing Flame had taken the duty of recuperating from war and manning the sacred Monastery and fought with hate in their hearts, and a thousand fold more when their ancient nemesis, the Crow's Children, appeared from the Warp and descended on Stormguard.

Lord Crusader Graythorne Crowslayer, took forces from the Orders present, commanded by Paladin Captain Vitalleus and Knight Captain Kveldor, and hurried to the defense of Lor'dra's civilians while the remaining Knights held their Fortress-Monastery. By the time Graythorne's forces reached Stormguard, the heretical traitors had already begun to inflict horrors upon the people, with Daedelus at the center of the carnage. The Knights began the task of cleansing the colossal city of their foe while the Lord Crusader fought the Betrayer in single combat. This duel is said to have lasted hours before Graythorne emerged from the smoke with the severed head of the ancient Chaos Lord. His weapons and armor rent, he fought and slayed all remaining traitors before Paladin Captain Vitalleus found him to inform him that the city was saved, but Galadhor was near to falling.

The defending Knights, under the command of the Lord Chaplain Marsidias, had signaled their off-world brothers and allies, the Avengers of Arathor and the Astral Warriors, for aid. Even after the Lord Crusader's force returned to the Fortress-Monastery, it was nearly broken. The Knights bitterly fought and did not dare give the Necrons ground before the reinforcement arrived. However, the defenders of Galadhor were reinforced by the returning Order of the Iron Lance, which deployed its entirety of Knight-Hussar biker squads, landspeeders, and tanks onto the surface.

Over the span of days, the mobile force continued to harass and destroy key elements of the Necron forces to alleviate the pressure on the Knights manning the Fortress Monastery, before allied ships tore open the Warp and emerged above Lor'dra's orbit. With the combined forces of the Astartes Chapters, and the Avenger’s new Primaris marines as well as Primaris intended for the Knights themselves, Luxthoris was forced to retreat back to the Tombs below. The next few years were spent destroying and driving back the remaining necron forces scattered across the world. Battered and nearly devastated, the Penitent Knights struggled to rebuild both their ranks and the city of Stormguard.

Weary of their losses, the Lords convened to discuss the future: Would they accept the new Primaris forces offered by Guilliman. Under the advice of Chapter Master Aponatus of the Avengers, the Knights opened their ranks to the Primaris Space Marines. However, the Necron armies did not simply disappear. Taking their new "brothers" of the Primaris and light forces granted by their ally Chapters, the Penitent Knights spent the next few years completely exterminating what was left of the xenos host. This included skirmishes against the larger Necron armies, assaults on outposts established after their awakening, and the detonation of numerous Tomb complexes. They had lost most of their numbers, but in the end, the Penitent Knights had survived the bloody Red Dawn of the 42nd Millennium.