Hailing from the desert-ringed Death World of Praesidia, the Sons of Guilliman have a chequered past. Whispers persist that more than one of their number has fallen to the temptations of Chaos in the past, and the Chapter has a reputation for rash or wilful conduct bordering on Codex divergence.
They fight all the harder to prove themselves worthy of their prestigious name, however, and have won many great victories.
- The Siege of Lakadamon (953.M33) - The Sons of Guilliman, alongside several Tekarn armoured regiments of the Astra Militarum were besieged in the defence of the Hive World of Lakadamon by the hordes of the Ork Warboss Vorhgad Bloodfang. Despite vastly overwhelming odds, the Chapter successfully held the planet's defence for three Terran years until the siege was broken by the combined forces of the Night Reapers and War Bearers Chapters, fighting alongside a major taskforce from Battlefleet Tempestus to break the orbital blockade that encircled the beleaguered world.
- Cleansing of Salinas (Unknown Date.M41) - At an uncertain time in Imperial history, the Sons of Guilliman battled the Forces of Chaos on the world of Salinas. The exact nature of the Chaos forces is uncertain, but the Salinas records make mention of armoured warriors who could bend reality, and red-fleshed beasts that could swallow a man whole (these seem to bear a striking resemblance to the Unfleshed who later assaulted the capital city of Salinas). The records tell of a great battle near the city of Khaturian, where the Sons of Guilliman's force was completely wiped out. Later, a force of other Astartes described as, "giants in silver armour who smote the vile foe with lightning and faith," (presumably Grey Knights) came to the world and, after cleansing it, took the remains of the lost Sons of Guilliman back to their Chapter. However, 19 fallen warriors, along with their Power Armour, were buried under a collapsed building, and their bodies were only uncovered decades later. It should be noted that one such suit was worn briefly by Uriel Ventris of the Ultramarines. After restoring one of the Mark VI suits to full functionality, Captain Ventris wore this suit to combat the Unfleshed. All of the suits were eventually returned to the Sons of Guilliman, with Ventris' suit declared a Chapter relic.
- Judgement of Hellenus (801.M41) - Inquisitor Hector Rex assumed direct control over the entire 279th Assault Armada of the Imperial Navy and ordered the mutant population of Hellenus purged for crimes against genetic purity. At the height of this purge, a combined strike force consisting of Space Marines form the Sons of Guilliman, the Iron Lords and the Skull Bearers Chapters was gathered together to confront the mutant abominations holding the enemy capital. During this confrontation, the Iron Lords contingent became tainted by the mutants' hideous gene-taint, forcing their fellow Space Marines to purge them as well.
- Return of Honour (965.M41) - Captain Uriel Ventris of the Ultramarines 4th Company returned 19 sets of Mark VI Corvus Pattern Power Armour from Salinas lost by the Sons of Guilliman during the Salinas conflict. Uriel and his Sergeant Pasanius Lysane discovered the armour when searching the Gallery of Antiquities on Salinas, while returning to Ultramar from their Death Oath.
- Third War for Armageddon (999.M41) - The Sons of Guilliman participated in the Third War for Armageddon, committing 6 companies to the conflict against the massive Ork WAAAGH! of Ghazghkull Thraka.
Notable Sons of Guilliman
- Chapter Master Ansellus - Ansellus is the current master of the Sons of Guilliman.
- Captain Adharon (Excommunicate Traitoris) - A former Captain of the Sons of Guilliman Chapter, Adharon was corrupted by Chaos and gathered a warband of like-minded corrupted Astartes around himself from his former company, known as Adharon's Reavers, to raid and pillage the commerce of the Imperium of Man in the name of the Dark Gods. The Siege of Vraks represented the first time that Adharon's Reavers had operated in concert with other Chaos Space Marine forces.
- Captain Karch - Karch is the Captain of the Sons of Guilliman Chapter's 5th Company. He was part of the Imperial force that came to the aid of the Cemetery World of Certus Minor after answering a plea for aid from the Excoriators' Chapter Master, Zachariah Kersh. However, the Cemetery World had been invaded by the Black Legion Sorcerer Ygethmor, who had begun a ritual to drag Certus Minor into the Warp. Even as the captain and his company fought the Sorcerer's forces, Ygethmor's ritual opened a Warp rift that threatened to swallow the Cemetery World whole. To make matters worse, due to being his promity to the Warp, Karch gained the ability to use psychic powers, but also began to hear the voices of daemons who sought to corrupt him.
- Sergeant Constantinius the Liberator (Excommunicate Traitoris) - Constantinius the Liberator was a former squad Sergeant in the 4th Company of the Sons of Guilliman who turned to Chaos. Constantinius was part of a force left behind to cleanse the planet of Nova Terra of any remaining xenos contamination after a Tyranid attack on the planet. After discovering and destroying a Genestealer infestation amongst the planet's nobility, Constantinius was forced to put down a rebellion by the planet's population, who were enraged by their nobility's summary execution. Once the carnage had ended, Constantinius appeared before the crowd and announced the Emperor and His minions had turned him into such a monster, and Constantinius vowed to lead the people of Nova Terra to freedom. Constantinius and his followers started a bloody rebellion against the Imperium of Man, setting himself up as the planet's ruler after overthrowing the Imperial governor and renaming the world Constantinium. After amassing a sizeable army of renegades, traitors and Chaos Space Marines, Constantinius and his forces rampaged into neighbouring systems, initiating a war that lasted for thirteen years and ravaged the entire sector until a sizeable Imperial force (including three Space Marine Chapters, twelve regiments of the Imperial Guard and agents of the Ordo Hereticus) were mustered to drive his armies back. Even then, the war only ended with Constantinius' death at the hands of an agent of the Officio Assassinorum.
- Epistolary Hilesto Fabian - Hilesto Fabian is a powerful Sons of Guilliman Epistolary who was recruited from the world of Paraxus and served his Chapter for over 400 standard years. During the Third War for Armageddon, he fought alongside his Chapter's 3rd Company in the defence of Gate IX in the Ghattana Bay. Finding himself surrounded by hundreds of Ork Dreadnoughts, Stompas and Killa Kans, Fabian tapped into the Warp and summoned gigantic empyric fists to crush the Ork walkers clanking towards him. After three solar days of fighting and making extensive use of his telekinetic powers, Fabian finally succumbed to exhaustion, as the ruins of a Gorkanaut lay crumpled beneath his feet.
- Sinos - Sinos killed an Evil Sunz Kult of Speed Warboss named Garmek Oil-Guzzler in the Third War for Armageddon.
- Redemptor Dreadnought Oriax (KIA) - Oriax was a Redemptor Dreadnought in the Sons of Guilliman Chapter who was part of the strike force that fought to save the world of Drevaris from the invading T'au Empire. Along with their Silver Skulls allies, the Sons of Guilliman fought a devastating battle with the T'au. Oriax was slain when he exploded after being struck by a KV128 Stormsurge's Pulse Cannon.
A blue High Gothic numeral is stenciled to the right of the squad specialty symbol on the inside of the shoulder plate, indicating squad number.
The colour of the left knee plate indicates company number in accordance with the dictates of the Codex Astartes -- i.e. white (1st Company), yellow (2nd Company), red (3rd Company), green (4th Company), etc.
The Sons of Guilliman's Chapter badge is a blue inverted Greek letter Omega imposed over a white roundel.
A pair of white wings (displayed and inverted) protrude from either side of it. This icon is centred on a field of blue.
- Adeptus Astartes: Successor Chapters (Limited Release Booklet)
- Codex Supplement: Ultramarines (8th Edition), pg. 24
- Codex: Armageddon (3rd Edition), pg. 30
- Codex: Chaos Space Marines (4th Edition), pp. 18-19
- The Killing Ground (Novel) by Graham McNeill, Chs. 11, 18, Epilogue, pp. 177, 273-274, 311
- Imperial Armour Volume Two, Second Edition - War Machines of the Adeptus Astartes, pp. 9, 17, 21
- Imperial Armour Volume Seven - The Siege of Vraks - Part Three, pp. 140, 172
- Insignium Astartes, pg. 63
- The Killing Ground (Novel) by Graham McNeill
- White Dwarf Weekly (30 May 2015), "Parade Ground"
- White Dwarf 21 (May 2018), "Battle Report - The Defence of Drevaris"
- Warhammer World Event - Warp Storm - Battle Brothers
- Warhammer World Event - Warp Storm Battle-Brothers 2