The Ultramarines 4th Company, known as the "Defenders of Ultramar," has a long and glorious history, stretching back to the dark days of the Horus Heresy when brother Space Marines fell in the bloodiest civil war ever to tear at the Emperor of Mankind's realm.
But the Ultramarines 4th Company also can be said to have a chequered history. Their battle record reflects some crushing blows suffered over the course of the millennia, yet it also shows countless victories and a strength of spirit that has seen the 4th rise up in the face of even the most horrifying odds, standing resolute in the name of Emperor and Primarch both.
This company's title is no mere honorific; to the 4th Company falls the duty of defending wider Ultramar from the predations of the countless heretics, aliens and monstrosities who would see it torn down in flames. This has seen them do battle with Tyranids, daemons, greenskins, T'au and Chaos Space Marine warbands beyond number.
In particular, the deeds of the 4th Company in battling Hive Fleet Leviathan have been immortalised in Chapter legend, though not in all cases for the best of reasons. Fighting alongside Deathwatch forces and the now-banished Ordo Xenos Inquisitor Kryptman, the warriors of the 4th Company battled the Tyranid menace upon the planet of Tarsis Ultra.
Here they launched a daring raid to slay the Norn-Queen coordinating the Tyranids' assault, succeeding only at great cost after introducing a hyper-mutative bio-toxin directly into the vast hive-node's physical body.
The Tyranid offensive collapsed as the guidance of the Hive Mind was torn away, and Tarsis Ultra saved for the time being. However, certain actions taken during that conflict were deemed to contravene the Codex Astartes, leading to severe censure from the Chapter Command.
Though they often utilise aggressive and fast-moving tactics in their pursuit, many of the battles undertaken by the 4th are defensive in nature. The 4th Company's Battle-Brothers act as castellans for the major fortifications dotted throughout Ultramar; they command the Ultramar Defence Auxilia garrisons stationed in these fastnesses, and their Techmarine-manned artillery pieces stand glowering watch over the approach to key bastions, sanctums and communication hubs across the miniature stellar empire of the Ultramarines.
To this end, the 4th Company can often be seen making use of massed fire support squads, Thunderfire Cannons, Vindicators and the like, relying on armoured transports and gunships to rapidly relocate their bristling gun-lines when the foe attempts to outmanoeuvre or bypass their strongpoints.
Battle of Calth
The 4th Company is known as the "Defenders of Ultramar" -- an accolade won in the Chapter's earliest history, when Chaos Space Marines from the Word Bearers Traitor Legion attacked the Ultramarines at the very heart of Ultramar.
It was upon the world of Calth that the greatest confrontation took place. Famed for its orbital shipyards, Calth was a typical world of the Realm of Ultramar. Its inhabitants were wealthy and generous, knowing little of want or fear. In many ways, their world was a paradise, but it was not to last.
When the Word Bearers Traitor Legion launched their attack against the Ultramarines, the strike against Calth was led by one of the Word Bearers' greatest champions, the former Master of the Faith, Kor Phaeron, the right-hand of the Word Bearers' Primarch Lorgar. This mighty Chaos Champion swore to utterly destroy the planet, and was very nearly successful.
From his personal Battle Barge, he directed a full-scale invasion of the Calth System. Calth's three sister planets were all destroyed, massive geo-nuclear strikes ripping them apart at the core. Calth's once gentle sun was laced with deadly heavy metals and substances that increased the star's radiation output ten-fold.
Within a standard century after the battle's end, the final elements of Calth's atmosphere would be burned off by its sun and the world left airless, its populace forced to dwell in gigantic underground caverns. But upon its surface during the still-raging conflict, the 4th Company fought the Word Bearers to a standstill.
The Traitor Marines held superiority in numbers, weaponry, and brutality, but the Ultramarines never gave in. As driven as the Chaos warriors of Kor Phaeron were, they could not dislodge the Ultramarines, many of whom had once called the planet home.
The war upon Calth was devastating and horrific. Ancient codes of warfare and martial conduct were broken and set aside by the Word Bearers as all manner of death and destruction was unleashed. The Ultramarines were stunned by the millions of Chaos Cultists the Word Bearers used as human shields and cannon fodder.
The Word Bearers, in turn, had underestimated the tenacity and resolve of their hated foe. In the end, Kor Phaeron was defeated when reinforcements from the Ultramarines homeworld of Macragge drove the Word Bearers from the surface of Calth. Kor Phaeron retreated all the way to the Maelstrom, a turbulent region of the galaxy much like the Eye of Terror where the Immaterium of Chaos seeps through into the material realm of the physical universe.
The Ultramarines were victorious, and the commander of the 4th Company, Captain Remus Ventanus, would one day set foot upon the shattered original Legion homeworld of the Word Bearers during the Great Scouring, symbolically capturing the Traitor Legion's abandoned homeworld of Colchis.
Creating the Codex Astartes
Following the actions of Captain Ventanus and the other Ultramarines under his command on Calth, they were eventually rescued by the remaining forces of the Ultramarines. The "Saviour of Calth" became one of Primarch Roboute Guilliman's closest advisers. Led by their erstwhile captain, the 4th Company, known in some circles as the "Troublesome Fourth," was a unit known for its daredevil actions, heroic follies and the personal bravery of its individual warriors.
They would become instrumental in helping to play out the strategies and military tactics devised by Primarch Guilliman in simulated battles -- the results of which would help lay the foundation of his greatest work -- the Codex Astartes.
It contained solar decades of accumulated wisdom, each chapter and verse a fragment of Guilliman's biologically encoded genius, each morsel of imparted knowledge a building block that would combine to form a work immeasurably greater than the sum of its parts. If the Primarch's work could be made to stick with the 4th Company, then it would stick anywhere. Where the 4th Company led, the other Battle Companies of the Legion followed.
Guardians of the Eastern Fringe
The Ultramarines have always held the Eastern Fringes of the galaxy in the vast Ultima Segmentum against the forces of darkness that threaten the Imperium from beyond the Halo Stars, and the 4th Company has a special hatred for the savage xenos invaders known as the Tyranids. Rapacious, extra-galactic predators, these relentless alien killers consume all before them in their quest for bio-matter to feed the ever-hungry biological factories of their Norn-Queens.
The first Tyranid Hive Fleet, code-named Behemoth, smashed into Imperial space in 745.M41 and descended upon Macragge in a fury of talon and claw. Forewarned of the coming xenos danger by the Inquisitor Kryptman, the Chapter Master of the Ultramarines, Marneus Calgar, stood ready to face the deadly aliens, but nothing could prepare his warriors for the sheer horror of what was to come.
Commanded at this time by Captain Idaeus, the 4th Company fought at the forefront of the invasion and were instrumental in the destruction of several of the larger Tyranid vessels. At last the invasion of Hive Fleet Behemoth was repulsed, but at terrible cost; the entirety of the Ultramarines' Veteran 1st Company was wiped out defending the northern polar defences of Macragge and many great heroes of the Astartes met their end. The Ultramarines had won the First Tyrannic War, but Kryptman assured Calgar that the Tyranids would be back.
With the destruction of Hive Fleet Behemoth, the Ultramarines set about consolidating their hold on the interstellar Realm of Ultramar. Many of their best and bravest warriors had fallen to the Tyranids, and with their strength thus depleted, many other alien and piratical raiders took advantage of this lapse in security and launched their own raids throughout Ultramar to sack worlds previously unassailable.
Thus it was that the 4th Company -- which had been at full strength when the Tyranid fleet attacked – had come through the war with the fewest casualties, and were thus the first called upon to help liberate Vorhn’s World, a Shrine World of the Ecclesiarchy in a neighbouring sub-sector.
The Ork Warlord known as the Arch-Maniac of Cabela had seized the world, enslaving its population and defiling the holy temples of the Emperor. Such barbarity could not be countenanced on such a holy world and thus the 4th Company was tasked with its liberation. Idaeus once more led his warriors into battle, using a combination of rigid adherence to the words of the Codex Astartes and an uncanny ability to adapt to rapidly changing battlefield conditions to circumvent many of the Ork strongpoints and destroy the most vital elements of their defences.
With much of their energies spent hunting down the Space Marine raiders in their midst, the Orks were unable to repulse the massed tank companies and regiments of the Imperial Guard's Jovian Hussars who overran the Greenskins with an unusually low casualty rate. It was during the cleansing of Vorhn’s World that a young Space Marine named Uriel Ventris first came to Idaeus' attention.
Descended from the legendary Lucian Ventris, who had died fighting the Tyranids of Hive Fleet Behemoth beneath the polar defence fortress 180 years before, Uriel displayed an exemplary courage, even amongst warriors for whom heroic feats of bravery were the norm. Taking command of his squad when his sergeant was killed by an Ork warlord, Uriel displayed the qualities that would one day lead him to command the 4th Company itself.
With the liberation of Vorhn's World, the task was now to secure the borders of Ultramar, and upon their return from the victorious campaign against the Orks, Idaeus' company joined their Battle-Brothers in securing the borders of Ultramar against further attack. For the next 5 standard years, the company patrolled the northern borders of their realm, running interdiction attacks and boarding actions against any and all raiders they encountered. Aboard the Vae Victus, an honourable Strike Cruiser commanded by Captain Lazlo Tiberius, himself a scarred veteran of the Tyrannic Wars, the 4th Company destroyed over 300 enemy vessels and achieved the highest number of kills to add to the banner in their company chapel.
Over the next few years, between occasional returns to Macragge for obeisances at the Temple of Correction, where the stasis-sealed, mortally wounded form of the Primarch Roboute Guilliman watches over his Chapter, the 4th Company regained its strength and inducted many new members. Returned to full combat readiness, the company was once again fit for duties beyond the borders of Ultramar and in the Mereneas Core, the company was to earn the gratitude of the Adeptus Mechanicus when they boarded and destroyed the Space Hulk Flame of Iniquity, an agglomerated structure of scores of derelict starships that threatened a number of their Forge Worlds, the giant factory planets where much of the armed might of the Imperium is produced.
Following this success, the determination and courage of the 4th Company came to the attention of Inquisitor Markhov, who was in need of warriors of such great skill. He petitioned Marneus Calgar for the Ultramarines' assistance in a matter of grave urgency. Calgar consented to allow the 4th Company to be seconded to the Inquisition's service and Idaeus' company was despatched to the world of Epsilon Regalis -- a world later to be made infamous by the Witch Hunter Tyrus.
Precisely what occurred on this world has never been made known, the events subsequent to the Ultramarines deployment on Epsilon Regalis having been sealed by the order of the Ordo Hereticus. Immediately following this mysterious mission, the 4th Company were involved in the eradication of several indigenous life-forms on the world of Horranveth to allow colonisation by an Adeptus Mechanicus Explorator team to proceed. Many among the Ultramarines felt that this type of combat was beneath them, but none dared defy their Chapter Master's decree.
Following the purgation of Horranveth, the company was recalled to take part in the Balur Crusade, a mixed- Chapter-force led by Marneus Calgar himself. A strong coalition of xenos creatures (identified as the T'au, Kroot and Tarellians) had launched an attack into Imperial-held space and demanded that the inhabitants of the captured worlds swear allegiance to their blasphemous empire.
Naturally, such naked aggression could not go unanswered and together with warriors of his own Ultramarines and from the Blood Angels, Marines Malevolent and the taciturn remnants of the Scythes of the Emperor Chapter, Calgar led the combined Space Marines army to swift victory, destroying the nascent xenos colonies and re-establishing Imperial rule.
Return of the Tyranids
The 4th Company were to fight the Tyranids again on the world of Ichar IV when the Tyranids returned with yet another Hive Fleet, this time known as the Kraken. Far from the battering ram of Hive Fleet Behemoth, it appeared that the Tyranids had somehow learned from their defeat centuries before and attacked in a series of smaller, yet no less lethal splinter fleets -- advancing across a much wider front.
Many of these fleets were destroyed, driving the aliens to consolidate their attack on the industrial world of Ichar IV. The Tyranid threat was met with courage and steel, the men of the Ultramarines fighting alongside hundreds of Imperial Guard regiments and elements from 7 other Space Marine Chapters. The 4th Company were again in the forefront of the fighting, with Idaeus and Uriel both awarded the Imperial Laurel for their heroism.
Once more the aliens were repulsed, though the threat of Hive Fleet Kraken remained strong. The Tyranid fleet broke into a number of smaller fleets as it retreated from Ichar IV and it is known that many of these splinter fleets penetrated deep into the galactic core. Some even reached as far as the Segmentum Solar though the massed guns of the Imperial fleet destroyed these without mercy. However, whether every one of these Kraken splinter fleets has been destroyed remains unclear.
Following the defeat of the Tyranids at Ichar IV, the 4th Company was despatched to the world of Thracia, where the rumoured deployment of the Night Lords Chaos Space Marines necessitated a force capable of meeting them blade-to-blade. Regiments of Imperial Guard pushed towards the planetary capital city, meeting stiff resistance, but crushing all before it.
As the campaign progressed, the Imperial lines became lengthy and strung out -- all too easy to attack and destroy from the flank. Realizing this, the 4th Company attacked the bridges that would allow such an attack, but in the process Captain Idaeus was lost, heroically sacrificing his own life to destroy the last bridge.
Mourning his loss, the 4th Company returned to Macragge, whereupon Veteran Sergeant Uriel Ventris was elevated to the rank of Captain and commander of the company.
Together with the newly appointed Captain Uriel Ventris, who had replaced Captain Idaeus after his heroic death, the 4th Company set off on their latest mission; to escort Adept Barzano of the Administratum to the troubled world of Pavonis. On the Eastern Fringe, Pavonis had been plagued by piratical raiders and civil insurrection and upon the Ultramarines' arrival, the planet was very nearly plunged into a bloody civil war between its competing industrial cartels.
Captain Ventris and Adept Barzano (now revealed to actually be an Inquisitor of the Ordo Xenos) went on to discover that the planet's troubles were at the instigation of a madman named Kasimir de Valtos who desired the release of an ancient and powerful C'tan Star God who had been imprisoned beneath the surface of Pavonis for tens of millions of years.
De Valtos was ultimately thwarted, though the ancient being known as the Nightbringer was freed from its aeons-long slumber and set loose amongst the stars. Only time will tell whether its escape will cost the Ultramarines and the galaxy dearly.
With peace and Imperial rule restored to Pavonis, the 4th Company journeyed to the northern reaches of Segmentum Tempestus to the world of Tarsis Ultra – a world brought into the Imperium by Roboute Guilliman himself during the early days of the Great Crusade -- and a world with a proud history of upholding the traditions of the Ultramarines.
Ancient oaths of brotherhood bound the fate of Tarsis Ultra to the Ultramarines and when a gargantuan Space Hulk drifted in-system, Captain Ventris led his men deep into its haunted depths to destroy it from within. Buried deep within its structure, the Ultramarines discovered nests of frenzied Orks and something much worse: Genestealers.
The fighting within the hulk was amongst the fiercest encountered by the 4th Company, but its warriors were able to fight their way clear of the hulk and watch its destruction from the bridge of the Vae Victus. But the victory was tinged with dread, for the Astartes vessel's Astropaths detected the forward edge of a bow wave of Warp interference – a phenomenon known as the "Shadow in the Warp" – which could mean only one thing. The Tyranids were approaching the borders of the Imperium once more.
The Defence of Tarsis Ultra
With warning of the approaching Tyranid hive fleet given, the Imperial response was unusually swift. The Ultramarines contacted a brother Chapter of Space Marines, the Mortifactors, though they had diverged considerably from the ideals of Roboute Guilliman -- embracing a culture of death worship. A fleet led by the Imperial Navy Admiral Bregant de Corte aboard the battleship Argus was assembled, including many ancient and noble ships of war; the Sword of Retribution, and the Kharloss Vincennes to name but two.
Imperial Guard soldiers from the Death Korps of Krieg and the Logres Regiments were shipped in and the local Planetary Defence Forces trained by Sergeant Learchus using the methods of the Ultramarine training barracks. Inquisitor Lord Kryptman once again lent his expertise to the commanders of the defence of Tarsis Ultra as well as bringing an elite Deathwatch Space Marines Kill-team led by the justly famed Watch Captain Bannon. As far as any world could be defended, Tarsis Ultra was as secure as it could be made given the time available to its defenders.
Battle was joined in the system's outer reaches and though the world of Barbarus Prime was lost to the Tyranids, the first elements of their fleet were defeated. The advance of the Hive Fleet could not be stopped and Kryptman was forced to sacrifice the world of Chordelis -- ordering the Mortifactors to Virus Bomb it from orbit before the Tyranids could assimilate its biomass. Despite fractures appearing among the Imperial commanders, the Tyranid threat was met with courage and honour on the surface of Tarsis Ultra, though the defenders were hard-pressed to stave off the relentless attacks of the aliens.
Though many thousands of lives were lost, and a huge proportion of the 4th Company was slain, the Tyranids were once more defeated when Captain Ventris cast off the teachings of the Codex Astartes and took command of the Deathwatch Kill-team. He led them on a last, desperate mission to deliver a lethal gene-poison to the heart of the last remaining Hive Ship.
Having once served with the Deathwatch, Captain Ventris knew that this was where he could do the most good, and despite the grim warning from Veteran Sergeant Learchus that Marneus Calgar would hear of his flouting of the Codex, he set off on his mission. Through alien terrors and biological horror, the Deathwatch Space Marines and Captain Ventris were successful and the gene-poison was administered to the Tyranid Norn-Queen.
Driven into spasms of uncontrolled mutation, the Norn-Queen died and her death throes drove the slave Tyranid organisms connected to her via the gestalt psychic consciousness of the Tyranid Hive Mind into paroxysms of feral self-destruction. The Tyranids were defeated, but like Ichar IV before it, the genetic taint of the alien invasion would forever be impossible to remove from the surface of Tarsis Ultra -- and the souls of its surviving population.
With Tarsis Ultra secured, the 4th Company gathered its dead and returned to Macragge, the hearts of its warriors heavy as they contemplated the cost of honouring their ancient debt. But something worse was awaiting the 4th Company upon their return to their homeworld. Allegations of heresy awaited Uriel Ventris for his actions on Tarsis Ultra and with them, the potential to strip the company of its honour.
Captain Ventris was spared the expected execution for his breach of Ultramarine doctrine and instead given a Death Oath by Marneus Calgar: he and his faithful companion, Sergeant Pasanius Lysane, were to seek out "a place of dark iron" where twisted reflections of the Space Marines were being wrought. Shortly after departing Macragge, Ventris' starship was attacked by Warp entities directed by a daemon imprisoned inside a Daemon Engine called the Omphalos Daemonium.
This Daemon Engine resembled a huge, grotesque steam locomotive, which could travel between the Warp and realspace. The two Space Marines were seized and taken deep within the Eye of Terror to Medrengard, the Daemon World that was the home of the Iron Warriors Traitor Legion. The pair soon linked up with a band of Renegade Space Marines and two surviving former Imperial Guardsmen, who were escaped slaves of the Iron Warriors. The group became a self-styled guerilla band, engaging in hit-and-run attacks against the Iron Warriors.
Ventris, Pasanius and the band of guerillas were eventually captured by Warsmith Honsou of the Iron Warriors, and after defying him, Ventris was "implanted" in the womb of a Daemonculaba, a genetically-modified woman whose womb had been amplified with Imperial Fists gene-seed the Iron Warriors had stolen during the 13th Black Crusade from the world of Hydra Cordatus and which was intended to turn normal adolescents into new Chaos Space Marines.
This twisted biotechnology was a mechanism intended to accelerate the development of new Traitor Marines in the laboratories under Honsou's fortress. These new Chaos Space Marines were intended to refill the ranks of the Iron Warriors Legion, which had been unable to replace its losses over the 10 millennia since the Horus Heresy. The Daemonculaba were also the mutated creatures that Uriel and Pasanius had been tasked with destroying in the first place.
At the same time, Honsou was under siege by rival Iron Hands Warsmiths for refusing to hand over their share of the untainted Imperial Fists gene-stock taken after the invasion of an Imperial facility on Hydra Cordatus. As the fighting raged, Ventris and Pasanius managed to get free and succeeded in destroying Honsou's labs and his fortress, although in order for this to happen they had to release a captive Khornate Daemon Prince.
The Daemon Prince then annihilated the rival daemon it had previously imprisoned in the Omphalos Daemonium, destroyed Honsou's fortress and minions, and attacked Honsou's rivals, driving them away. Later, Uriel, Pasanius, and a group of the so-called Unfleshed, who were the mutant rejects of the Iron Warriors' experiments to make new Space Marines using the Daemonculaba, escaped from the Eye of Terror on the Omphalos Daemonium, which had reverted to a normal starship.
However, the former Daemon Engine brought them through the Warp to a troubled world called Salinas, and more specifically to a forbidden zone on that world's surface that reeked of death. Ventris and Pasanius were then confronted by the veteran Imperial Guard regiment that ruled the planet as a gift of conquest, and the suspicious and ruthless Planetary Governor, the regiment's ex-commander. They requested help in reaching Macragge, but their astropathic transmission was intercepted by the Grey Knights, who were monitoring Salinas for other reasons.
A squad of them arrived on the planet, arrested Ventris and Pasanius, and after grueling physical, mental and spiritual trials declared them untainted by their exposure to Chaos during the events on Medrengard. In the meantime, it was revealed that a powerful psyker had likely brought the Omphalos Daemonium to Salinas in order to use the freed Unfleshed as an instrument of revenge against the governor and his former regiment.
This was vengeance for the regiment's murder of tens of thousands of civilians, including the entire population of a town that was the birthplace of many of the leaders of a small-scale guerilla campaign that now operated on Salinas. The campaign itself had been caused by the brutality and heavy-handedness of the Imperial Governor.
This ravished town was the forbidden zone the Ultramarines had first found themselves in when they arrived on Salinas. After being possessed by the psyker, the Unfleshed went on a killing rampage, but they were eventually killed by Uriel, Pasanius, and the Grey Knights, who subsequently returned the Ultramarines to Macragge.
Return to Pavonis
Having successfully completed their Death Oath, Uriel and Pasanius were welcomed back to the homeworld of their Chapter but were subjected to interrogation and tests by the Chief Librarian to insure they had not been tainted by their time on the Daemon World of Medrengard.
After both Uriel and Pasanius were deemed free of Chaos taint, Uriel was reinstated as Captain of the Ultramarines' 4th Company and given the opportunity to prove himself in the eyes of those who still doubted him by returning to the world of Pavonis and defending it from T'au invaders.
Pasanius was not so fortunate, as he was demoted in rank and forced into one hundred solar days of isolation from the Chapter. This harsh treatment was a punishment for hiding the unusual regenerative abilities of his bionic arm, which he had gotten after the C'tan called the Nightbringer had scythed off his biological arm during the earlier Ultramarines mission to Pavonis.
Apparently because of this contact with the C'tan, the bionic arm had become infused with the Necron's living metal, the substance called necrodermis. After one hundred days he was reinstated as a Battle-Brother of the 4th Company and rejoined his captain.
Invasion of Ultramar
In the meantime, the Warsmith Honsou was consumed by hate for Ventris and the Ultramarines following the events on Medrengard and the destruction of his Chaos Space Marine incubation experiments. He hatched a plan to annihilate the Ultramarines, and especially Uriel Ventris. As bait, he used a stolen Mechanicus virus to turn Tarsis Ultra, the world the Ultramarines had vowed to protect, into a Dead World.
He had assembled a large invasion force, which apart from his Iron Warrior warband, included Chaos Cultists, Traitor Marines and Traitor Guardsmen, Drukhari pirates, Kroot and other alien and human mercenaries, a Dark Mechanicum force led by the Traitor Magos Cycerin, and a multitude of criminals, psychopaths and killers.
Honsou managed to find and board a star fort hidden for the previous 60 Terran years in the depths of uncharted space in the Ultramar Sub-sector, guarded by an Ultramarines contingent. He slaughtered the star fort's Ultramarines garrison and then freed the powerful Daemon Prince M'kar, secretly held captive within the fort.
The daemon, who had once been the Word Bearers Dark Apostle named Maloq Kartho who had originally attacked Ultramar during the Horus Heresy, had been imprisoned by Marneus Calgar, the Chapter Master of the Ultramarines, with the help of the Inquisition.
M'kar hated the Ultramarines Chapter and the Imperium of Man with a passion. Aligning with Honsou, the Daemon Prince possessed a desecrated Ultramarine Dreadnought shell so that he could interact with the material universe, turned the star fort into a Chaos abomination linked directly to the Warp, and called forth a huge daemon army to join in attacking the worlds of the Realm of Ultramar.
Honsou had managed to acquire a clone of Uriel Ventris, known as the "Newborn," who had been created from the genetic material left behind while Uriel was in the womb of the Daemonculaba on Medrengard. The Newborn was a psychic as well as physical clone of Uriel. As such, he had fragments of Uriel's knowledge and memories, including the defence protocols of Ultramar, which Honsou first used to attack the star fort, and then the entire Realm of Ultramar.
The whole Chapter rose in defence of the realm, aided by an Adeptus Mechanicus contingent under Magos Locard, the warband of the system-based Ordo Malleus Inquisitor Suzaku, a squad of Raven Guard Space Marines, the mobilised Ultramaran Planetary Defense Force regiments, and many civilians. The war expanded to encompass several Ultramarran worlds, at least one of which was destroyed. Finally, Uriel confronted the Newborn (and Honsou), on Calth, his planet of birth.
Honsou had gone there at the request of M'kar, to the Tomb of Remus Ventanus (an ancient Ultramarine hero of the 4th Company known as "the Savior of Calth") to destroy Ventanus' sarcophagus and his wargear. Uriel killed the Newborn using a blade that was part of Ventanus' wargear, and in the battle that followed Honsou's more numerous force was defeated thanks to the sudden appearance of spectral guardian-warriors.
Honsou, faced with capture or death, detonated the explosives the Iron Warriors had previously placed around the tomb, collapsing the grand edifice of the Tomb of Ventanus on top of himself and his opponents. Uriel and some of his fellow warriors survived and headed to Talassar, an Ultramarran world where M'kar and his daemon army were close to overrunning Chapter Master Calgar and his dwindling forces.
Uriel and other friendly reinforcements arrived in the midst of the final, climactic battle for the world. Ventris tossed the powerful, anti-daemonic Blade of Ventanus to Calgar as the Chapter Master was duelling with M'kar, and Calgar used it to completely annihilate the Daemon Prince.
With the daemon army and Honsou's forces defeated in all the theatres of the war, the Imperial forces proceeded to engage in mopping-up operations, and within six solar months, the Realm of Ultramar was declared free of the touch of Chaos. Ominously, while the ruins of the Tomb of Ventanus were searched thoroughly, the body of Warsmith Honsou was never recovered.
Since the return of Roboute Guilliman, the 4th Company have been further charged with overseeing the reclamation of the wider worlds of the original Realm of Ultramar, when it spanned some five hundred worlds.
In this capacity they have driven invading foes from many worlds that once belonged to the Ultramarines. They have also fought more than one war against recalcitrant insurgents and rogue governors who would rather risk the resurrected Primarch's wrath than let go their death grip on power.
- The Firebrands - The Firebrands were a Tactical Squad led by Sergeant Pasanius Lysane. They earned their name during the second Pavonis campaign, a which was a possible tribute to their sergeant's prodigious use of a Flamer.
- The Guardians - The Guardians were a Tactical Squad led by Sergeant Learchus Abantes. They earned their name during the second Pavonis campaign, when, under Captain Uriel Ventris' command, they executed a daring Drop Pod assault on the T'au's vulnerable rear that crippled their offensive.
- The Swords of Calth The Swords of Calth were the Command Squad of Captain Uriel Ventris. Ventris formed the squad during the Invasion of Ultramar in 954.999.M41, the first time he had ever built his own Command Squad.
Notable Defenders of Ultramar
- Captain Uriel Ventris - Uriel Ventris is the current Captain of the Ultramarines 4th Company.
- Chaplain Judd Clausel - Judd Clausel is the Chaplain of the 4th Company of the Ultramarines. Clausel has fought alongside several leaders of the company, including Captain Idaeus, his successor Captain Uriel Ventris and Sergeant Learchus Abantes, who served as acting captain for a time. A straightforward and violent warrior, he is prone to headlong charges and is often depicted cutting enemies in two with his Crozius Arcanum. Clausel cares little for talk, and has reprimanded members of the Ecclesiarchy for discussing theology during meetings, and threatened Planetary Governors when they are slow to act. Uriel Ventris once stated, "Chaplain Clausel speaks bluntly, but he is right to do so."
- Apothecary Selenus - The long-serving Apothecary to the 4th Company, Selenus accompanied Captain Uriel Ventris on several of his early missions, including the battles on Pavonis and Tarsis Ultra. In the aftermath of the devastating action on Tarsis Ultra, and Captain Ventris' banishment from the Chapter, Selenus, along with Chaplain Judd Clausel, assisted Acting Captain Learchus Abantes in screening the company's new recruits and rebuilding the company's numbers. Selenus also accompanied the 4th Company on its reconnaissance mission to Espandor, where he was instrumental in retrieving the gene-seed of Ultramarines who had fallen on the frigate Guilliman's Honour, before their remains could be ravaged by Orks. After Ventris' reinstatement to the 4th Company, Selenus also fought alongside him during the company's second deployment to Pavonis. During the Invasion of Ultramar, Ventris appointed Selenus to his newly-formed Command Squad, the "Swords of Calth." Ventris reflected that, although his medical skills were great, Selenus was first and foremost a warrior, and his knowledge of the physiology of all species made him that much more devastating in combat. Selenus survived the desperate fight in the catacombs of Calth against the Iron Warriors Warsmith Honsou, and carried out Raven Guard Shadow Captain Aethon Shaan's request to extract the gene-seed of Ardaric Vaanes, a Renegade Raven Guard who had nonetheless sided with the Ultramarines during the final battle.
- Veteran Sergeant Pasanius Lysane - Lysane was a Veteran Sergeant of the 4th Company of the Ultramarines, and the best friend of Captain Uriel Ventris. Like Ventris, Pasanius was born on Calth, and the two boys grew up together. As Aspirants to the Ultramarines, the pair remained together throughout their training at the Agilesus Barracks and their subsequent service in the Ultramarines. Before his induction into the Space Marines, Pasanius was already a towering youth, and as an Ultramarine, his physique was so massive that his Power Armour had to incorporate salvaged pieces of Tactical Dreadnought Armour to fit his frame. His primary weapon was a Heavy Flamer.
- Sergeant Learchus Abantes - Abantes is cool-headed and follows rules very closely, as opposed to his superior Captain Uriel Ventris. Learchus is one of Captain Ventris' most trusted sergeants, who often consults him. While Ventris was exiled in the Eye of Terror, Learchus took command of the 4th Company as its Acting Captain. On Ventris' return to command of the company, Learchus grew jealous, feeling that he had earned the right to command the company. Ventris was forced to remind him that the company remained his to lead. After this dispute broke out into the open, Learchus, to his credit, made clear to oppose any remaining doubt of Ventris within the company or Chapter. Later during the second campaign on Pavonis, Learchus took command of a Scout Squad and infiltrated the port of Praxedes, distracting the T'au long enough to allow the rest of the company's Drop Pods to safely land. On Calth during the Invasion of Ultramar, Learchus commanded an armored spearhead consisting of both Ultramarine and Planetary Defence Force vehicles. He attempted to stop an enemy convoy comprised of Warsmith Honsou's forces from reaching Guilliman's Gate, but was forced to retreat when a Traitor Baneblade appeared on the battlefield.
- Company Champion Petronius Nero - Nero currently serves as Company Champion in Captain Uriel Ventris' Command Squad, "The Swords of Calth." An exceptional close combat specialist, Nero first distinguished himself during the Second Battle of Pavonis as part of a raiding party infiltrating the T'au headquarters camp. Nero survived the collapse of the cavern engineered by the Warsmith Honsou, though he was grieved when his custom-made Power Sword was broken by the rockfall. As part of Ventris' Command Squad, Nero joined the defence of Calth from the invasion of the Bloodborn in 999.M41. When Ventris tracked Honsou to the underground tomb of Remus Ventanus, the Ultramarines were attacked by the Blade Dancers of Xiomagra. The Mistress of the Blade Dancers was far too fast for Uriel, but Nero stepped in and not only saved his life, but defeated Xiomagra with apparent ease.
- Captain Idaeus - Idaeus was the former Captain of the Ultramarines' 4th Company, who died shortly after passing his position on to his senior Sergeant, Uriel Ventris. Unusually for an Ultramarine, Idaeus was a pragmatic thinker, adhering to the Codex Astartes only when he more or less needed to. He knew when to bend the rules of engagement and when not to, and trusted his gut instincts, even when every other sign told him things were going as planned. He was widely respected by the men of the 4th Company, although his senior Veteran Sergeant, Uriel Ventris, had difficulty accepting his deviation from the Codex, even after winning victories with him over several solar decades. Idaeus' last campaign was on Thracia, where the Ultramarines were helping the Imperial Guard suppress a Chaos-fueled rebellion. The 4th Company was charged with destroying a number of bridges that the enemy could use to outflank the Guard as it advanced on the rebel stronghold. As they were laying the charges on Bridge Two-Four, they came under attack by Chaos Space Marines of the Night Lords Traitor Legion. Although outnumbered and outgunned, Idaeus could not retreat and leave the bridges intact, so instead they held their positions. When the Night Lords advanced across the bridge, with the bodies of slain Ultramarines impaled on the front of their tanks, Idaeus' fury was terrible, and he led a countercharge that drove the Night Lords back. With only seven Ultramarines left of his original force, Idaeus handed his Power Sword -- which he had forged himself before the Corinthian Crusade -- to Uriel Ventris, clearly intending that the sergeant succeed his as commander of the 4th Company, then stormed off alone to detonate the remaining charges with his Plasma Pistol. He died in the midst of a squad of Chaos Raptors, who recoiled in terror as he set off the explosives. Idaeus' reputation for "unorthodox" thinking went beyond the Ultramarines Chapter; shortly after Ventris was promoted to Captain, Inquisitor Ario Barzano requested the 4th Company's assistance in traveling to Pavonis, confident that he needed someone capable of thinking outside the strictures of the Codex. After the conclusion of the first Pavonis campaign, Ventris remembered Marneus Calgar's advice to him, that Idaeus may have been a great man, but he would have wanted Ventris to be his own man as leader of the company. Feeling that he had accomplished this, Ventris decided that, instead of re-forging the blade of Idaeus's sword, which had been broken during the final battle of the Pavonis campaign, he would keep the hilt, but forge a new blade himself. After Idaeus' death, the artificers of Konor created a master-crafted Plasma Pistol named in his memory.
- Captain Remus Ventanus - Remus Ventanus was the Captain of the Ultramarines Legion's 4th Company during the Great Crusade and the Horus Heresy. His actions during the Battle of Calth helped save the planet from complete destruction, cementing his status as an Ultramarines hero even into in the late 41st Millennium. His tomb on Calth became a major site of pilgrimage for the Ultramarines and the people of Ultramar, and played a key role in the victory of the Ultramarines over the forces of Chaos during the Invasion of Ultramar.
- Ancient Cessio (KIA) - The warriors of the 4th Company tell proud tales of Ancient Cessio, who earned his title engaging the insidious Genestealer Cult infesting the Hive City of Chanchados on Ponides III. Driven back to their last redoubts, the screeching cultist hordes threw themselves at the Ultramarines in a sudden and viciously synchronous counterattack. When the Company Ancient's skull was cracked open by an Aberrant's lumpen power hammer, it was Cessio who took up the company standard before it could fall. With a great cry of defiance, Cessio rallied his brothers, and they smashed into the cultists with a crunch of ceramite against flesh. Still holding the banner aloft, Cessio met the cult's monstrous Patriarch in single combat. Its lashing claws rent the Ancient's armour. Its psychic powers ravaged his mind. Yet with his dying breath Cessio lopped the monster's head from its shoulders and perished with the standard still propped aloft.
- Codex: Space Marines (5th Edition), pp. 23, 40, 96
- Codex Supplement: Ultramarines (8th Edition), pg. 15
- Chains of Command (Short Story) by Graham McNeill
- Consequences (Short Story) by Graham McNeill
- Courage and Honour (Novel) by Graham McNeill, Ch. 4
- Defenders of Ultramar (Graphic Novel) by Graham McNeill
- Iron Warrior (Novella) by Graham McNeill
- Leviathan (Short Story) by Graham McNeill
- Nightbringer (Novel) by Graham McNeill (2004)
- Warriors of Ultramar (Novel) by Graham McNeill (2004)
- Dead Sky, Black Sun (Novel) by Graham McNeill (2005)
- The Chapter's Due (Novel) by Graham McNeill in Ultramarines: The Second Omnibus, Chs. 8, 20, 22, pp. 621, 775–776, 800
- The Chapter's Due (Novel) by Graham McNeill, Ch. 8, pg. 106
- Know No Fear'' (Novel) by Dan Abnett
- Age of Darkness'' (Anthology) edited by Christian Dunn, "Rules of Engagement" by Graham McNeill, pp. 4-50