A Light in the Darkness

A Light in the Darkness is the name of the defensive planetary campaign carried out by the unforgiving and bellicose Murdering Sons Chapter against a large Chaos Warband on the Imperial world of Mortua Secundus in 999.M41.

History
At the closing of the 41st Millennium, the Imperium was assailed on all sides by the various foes of Mankind. To make matters worse, the fortress world of Cadia had fallen, causing the boundaries between the material universe and the Immaterium to tear a rift across the width of the galaxy, forming the Cicatrix Maledictum. The Imperium was effectively cut in half and thousands of Imperial worlds were assailed by rising Chaos cults, daemonic legions and Heretic Astartes warbands. Warp storm activity had made travel difficult and astral communication was virtually non-existent.

Soon word reached the Murdering Sons Chapter that a miracle had occurred - the long-dead Ultramarines Primarch Roboute Guilliman had been resurrected from his millennia-long slumber and now personally led his Indomitus Crusade outwards from Holy Terra to bring wrath and retribution to the unholy forces of the Immaterium. Though the Murdering Sons were elated to hear that one of the demigod-sons of the Emperor now walked the galaxy once more, they had no time to celebrate, as they were firmly entrenched in fighting the forces of the Archenemy.

When the Chapter arrived upon the backwater world of Mortua Secundus to free the population from their daemonic overlords, they soon found themselves severely outnumbered by the untimely arrival of a large host of Heretic Astartes comprised of the Night Lords and the Word Bearers renegade warband known as the Host of the Truthbringer. Sending a desperate astro-telepathic cry for assistance, the Murdering Sons dug themselves in as best they could and vowed to make their last stand against the superior Chaos force, determined to sell themselves dearly and take as many of the Heretic scum with them. Their salvation arrived in the form of a small Imperial taskforce comprised of several Astra Militarum regiments and led by a small cadre of Adeptus Custodes and Sisters of Silence.

Teleporting amongst the ranks of the foe, bolters roared and crackling blades tore through heretic battle-plate and flesh, as a Custodian Shield-Captain led the assault that saw the traitor forces’ cohesion shattered. Inspired by the sudden arrival of the Emperor's most faithful servants, the Murdering Sons launched their own counter-attack against the heretic forces, and soon, the blood of both Loyalist and heretic stained the ground as corpses were piled in gory heaps as the Night Lords, Heretic Astartes and their daemonic allies fought back furiously. After two days and a night of unremitting savagery, the Chaos host was broken.

The Shield-Captain then approached Lucius Mordua and presented the Chapter Master with a gift of the utmost importance - a company of newly created Primaris Space Marine reinforcements. He also presented to the Chapter's Techmarines the secrets behind their creation and the means to continue producing more of these superbly-wrought warriors, so that the Chapter could replenish their sorely depleted ranks. The Murdering Sons understood the gravitas of what they had been offered and graciously embraced the Emperor's beneficence in their hour of need.