Damnos, an Imperial Mining World located in the Ultima Segmentum, was first colonised by the humans of the Imperium of Man during the Great Crusade, though in fact it was actually already an ancient Necron Tomb World.
The Necron presence was first discovered in the north by the Imperials after their awakening in 973.M41, whilst the city of Mandos Prime's geothermic fusion stations were under repair following severe seismic activity. The Adeptus Mechanicus Tech-priests rapidly claimed the right to the xenos artefacts and extradited several specimens to the nearby Forge World of Goethe Majoris for closer study.
Soon after, under waves of atmospheric interference that clouded the entire northern hemisphere of the planet, the Necrons emerged from their tombs.
The planet went on alert, but the threat was incomprehensible, no warning had been received from the fallen hive cities, and any reconnaissance units deployed never returned. As more hive cities toppled to the unknown invaders, word of the assault finally got through to the Planetary Governor, who deployed every regiment under his command.
Within six solar months almost all of Damnos' vast manufactorum hive cities were in ruins, and the planetary capital of Kellenport finally fell to the Necron forces in 974.M41.
The 2nd Company of the Ultramarines answered the planet's distress call in 974.M41 and helped to evacuate the remaining Imperial survivors before the Imperial Navy unleashed an Exterminatus-level orbital bombardment upon the planet's surface at the request of the Adeptus Astartes that was erroneously believed to have eliminated the Necron threat.
This campaign became known as the Damnos Incident in Imperial records.
In the wake of the failure to clear Damnos of its Necron presence, the Ultramarines 2nd Company under the command of Captain Cato Sicarius returned to the world in 999.M41 to eliminate the xenos once and for all.
The liberated but enraged star god proceeded to assault Imperial and Necron forces alike until Cato Sicarius banished the entity into the Warp using a Vortex Grenade.
In the wake of the Second Battle of Damnos, the battered world's remaining Necron tomb complexes were cleared of all remaining resistance by the Ultramarines and allied Astra Militarum troops.
The citizens of Damnos whom Sicarius had rescued solar decades before were restored to the world and allowed to begin to redevelop it into a productive Imperial colony.
"They came with the ice, so the natives would later tell us. But the truth was they had always been there, slumbering, waiting. We knew little about them during that first encounter, save that they were ages old and hard to kill. We know precious little more now. The dead don't stay dead, not on Damnos. They came back, from up out of the ice, and we shed much blood to put them back beneath it. We are Ultramarines. The exemplars. Our victories are many, but against the enemy on Damnos we tasted that rarest of things, a word I thought lost to our vocabulary – defeat. Few foes have ever claimed that over us, but in the Necrons we found a worthy and most terrible one. In the necrons, we found a nemesis, and one which we were destined to meet again."
- — Chapter Master Marneus Calgar, after the so-called "Damnos Incident"
The Strike Cruiser Valin's Revenge with the Ultramarines 2nd Company aboard arrived just as the final Necron assault on the world's capital city of Kellenport had begun. Captain Cato Sicarius ordered the cruiser to move into low orbit above Kellenport to begin a ground assault. The 2nd Company launched in three groups of Drop Pods.
The first with Captain Sicarius struck the Necron forces in the very heart of their siege lines, scouring the machine warriors from the capital city's outer walls. The second group of Ultramarines under the command of Chief Librarian Varro Tigurius hit home amidst the Necron Gauss Cannon and Gauss Pylons whose fire was raining down upon the remaining Imperial defenders of the capital.
The third wave of Ultramarines, consisting entirely of unmanned Deathwind Drop Pods, slammed into the broken rubble outside the besieged capitolis administratum, firing waves of missiles into the Necrons' ranks. The first strike force advanced against a Necron command node.
Their target was the Necron Lord commanding the assault. Captain Sicarius assaulted his position with his most experienced battle-brothers and the Dreadnought Agrippan. Sicarius was badly wounded in the assault and for a moment it looked like the Necrons would earn the victory, but the Dreadnought Agrippan attacked the Necron Lord and with a single blow he destroyed that nefarious enemy commander.
With their leader, the only truly sentient Necron, destroyed, the Necrons reverted to their secondary command protocols and began to retreat. Captain Sicarius was taken to the Strike Cruiser's medical bay and Tigurius took command over the remaining Ultramarines.
Later Tigurius and Agrippan were forced to acknowledge that Damnos was lost to the enemy. They initiated an evacuation of as many of the planet's inhabitants as possible. When the new Necron assault began most of the planet's inhabitants were already gone, and only the Ultramarines and the Kellenport-based regiment of the Astra Militarum were still on the ground.
The Ultramarines defended the city valiantly, slowly falling back to the spaceport. As the last Thunderhawk gunships landed to evacuate the survivors, only forty Space Marines and twenty Guardsmen were still alive. In the final moments of the battle, the Dreadnought Agrippan fell, pinned between a dozen streams of Gauss Cannon fire.
As the Thunderhawks sped Tigurius and the last of the Imperial defenders to the safety of the Valin's Revenge, Agrippan's internal Plasma Reactor went critical and the resulting explosion destroyed Damnos' capital city and every Necron within it. Later, Damnos was bombarded by the vessels of the Imperial Navy from orbit, destroying the planet's surface and ending the Necron threat on Damnos -- at least as far as the Imperium was aware.
Since Sicarius and his men were able to evacuate large swathes of the world's population from certain death, the mission was not a complete failure. However, the Ultramarines failed in their primary objective of destroying the Necron threat that had emerged on Damnos.
Sicarius was determined to not let such a slight go unanswered for long. For the first time, he had tasted bitter defeat in battle and it was a black mark that would twist within his heart for the next twenty-five standard years. In future battles, his violent displays of courage became reckless to the point of unnecessarily endangering the lives of his men and every victory after Damnos rang hollow to him.
In the aftermath of Damnos, as Sicarius recovered from the wounds he had suffered, Sergeant Chronus was by unanimous assent honoured with the title of "Spear of Macragge", a title rarely bestowed in the history of the Chapter and only given to an Astartes who was considered a great hero of the Ultramarines. Some say this was a move by Sicarius' detractors to lessen his influence.
Return to Damnos
Despite the Inquisition's efforts to suppress all knowledge of the Necrons' reemergence into the galaxy, the Imperium's faith in its military supremacy was shaken by the news that spread across the galaxy after 974.M41 that these xenos had overcome both the Imperial Guard and the Ultramarines at Damnos.
Eventually, reports of the loss of Damnos made their way to Terra, where both the Fabricator-General of the Adeptus Mechanicus and the High Lords of Terra decreed that the Ultramarines must return to Damnos and eradicate the Necron threat once and for all.
Twenty-five standard years after the Damnos Incident, in 999.M41, this Imperial order was brought to Macragge by the experienced Deathwatch strike team led by Squad Lazarius. Chapter Master Marneus Calgar was not pleased with the Imperium's decree, for he knew that his 2nd Company had faced only a fraction of the awakened Necrons on Damnos a quarter of a Terran century before. Once they returned to Damnos, the Ultramarines would face the entire strength of a Necron Tomb World and risk the deaths of hundreds of the Chapter's Astartes.
Yet, Calgar knew that the High Lords of Terra were right and that the Necrons on Damnos must be defeated if the Imperium was ever to know peace in the face of the growing Necron threat. With the record of the Ultramarines stained by the action on Damnos, it was their duty to banish the ghosts of the past. Upon hearing Calgar's announcement that the Ultramarines' 1st, 2nd, 3rd, 5th, and 6th Companies, accompanied by elements of the 10th, would return to reclaim Damnos for the Emperor, Cato Sicarius smiled for the first time in solar decades.
It is said that during the preparation for the assault, Sicarius trained so hard that he fought with the fury of a man possessed and even slept in the cage-vault. Before the solar month was out, Calgar's armies and fleets had been assembled and over 500 Space Marines stood ready for war. In addition, Sicarius was granted a Vortex Grenade by the Deathwatch Sergeant Davian Imocles, who was rumoured to be an old friend and former squad mate.
The journey to Damnos was a perilous one, with Calgar relying on various ruses and distractions to get his warriors safely to the planet's surface. By the time the Necrons had spotted the true location of the Ultramarine warships, the Astartes fleet was in a position to launch their Drop Pods.
The first wave consisted of unmanned variants designed to draw the fire of the Gauss Pylons. The second wave, however, represented the true assault, which brought hundreds of Space Marines as well as a number of vengeful Imperial Guard regiments to the heart of the Necrons' subterranean tomb complex.
Their objective was to destroy the pyramidal complexes that controlled the Necron power grid and to do it before the Imperial forces were overwhelmed. However, one factor that they did not account for was the physical incarnation of a C'tan, a C'tan Shard of Yggra'nya, the World Shaper, held within a Tesseract Vault. It was determined that this vault was the true source of the Necrons' power and must be neutralized if the Imperial forces were to have any hope of victory.
Despite the power brought to bear by the Imperial assault on Damnos, Marneus Calgar felt like a duelist being taken apart by a superior foe in the battle-cage. The xenos' battle logic proved impeccable, with its master intelligence anticipating the Ultramarines' every move and neutralizing each tactic they employed.
Thanks to an energy shield emitting from the vault, every plasma volley and melta blast employed against the Necron Monoliths dissipated harmlessly or detonated prematurely before it could harm the constructs.
Since the xenos had managed to analyze the Ultramarines' battle doctrine, Calgar realized he must attempt a completely unexpected strategem. Assaulting the ranks of the Necron Immortals, the Chapter Master jumped onto the metallic base of a malfunctioning Gauss Pylon and slowly pushed the war engine's crescent back until its viridian beam hit the energy shield of the floating necropolis. With a blinding flash of light, the energy shield protecting the tomb complex collapsed and the Tesseract Vault was broken wide open to reveal the enraged demigod imprisoned within.
A giant cruciform of pure light rose above the Necron army, the remnants of the C'tan's energy cage still crackling around it. Roaring in exultation at its newfound freedom, the booming sound threw Ultramarines and Necrons alike to the icy ground and cracked the planet's crust. Its first victim would be the Necron Overlord, the Undying, which the star god crushed with ease by transforming the earth around his metallic form into an oversized fist.
The Overlord phased out of reality, seeking to escape back to his subterranean lair. But deep underground, the surviving members of the Deathwatch's Squad Lazarius had reached their own objective. The Undying teleported back to his cabled sarcophagus right in front of the Deathwatch's eyes. Unfortunately for the Necron, the crack team of Astartes had replaced his revivification engines with melta charges and entropic destabilisers and proceeded to blast the Necron Overlord into atoms.
Back on the surface, the xenos reeled from the loss of their leader and the artificially intelligent command programs that had governed their warriors' every action. Meanwhile, the unleashed C'tan lashed out in fury at both its Necron enslavers and the Ultramarines as Captain Sicarius duelled a Flayed Ones lord. After ramming his Power Sword into the powerful Flayed One's torso, Sicarius summoned twenty-five Terran years of anger and frustration into a final burst of strength.
He unclipped the Vortex Grenade that had been given to him earlier and activated the weapon before throwing it at the enraged demigod hovering overhead. The grenade detonated and formed a spiralling orb of nothingness as its unstoppable force sucked the C'tan into the Warp before collapsing and winking out of existence. Sicarius felt a great weight lift in that moment, as he realised both he and the Ultramarines had been redeemed for their original failure on Damnos in the sight of the Emperor.
Over the next few solar days, the Imperials eliminated the surviving Necrons with grim efficiency. Empty tomb complexes were collapsed or detonated under the guidance of the Deathwatch and the citizens of Damnos whom Sicarius had rescued solar decades before were restored to the world to reclaim it for their own.
- Apocalypse: War Zone Damnos (6th Edition), pp. 7-24
- Codex: Necrons (7th Edition) (Digital Edition), "A New Epoch Begins"
- Warhammer 40,000: Rulebook (5th Edition), pp. 180-181
- Fall of Damnos (Novel) by Nick Kyme