- The Pegasus Expedition, lead by Lord-Knight Commander Aleksandr Ivar, arrives in the wild, unsettled Pegasus Gulf. The expedition is composed of thousands of colony ships escorted by two hundred combined regiments of Vostroyan Firstborn and the Royal Juno Grenadiers from the neighbouring Vandal Reach, and a small Mechanicus Exploratory fleet.
- The Ulyssian system is the first colonized. Ulyssia itself is raised as a grand hive world and serves as the hub of trade and government in the Gulf.
- The rest of the Pegasus Gulf is slowly colonized. A handful of indigenous sentient xenos species are exterminated or otherwise driven from the region or into hiding. In anticipation of an incoming Waaagh, Heavensreach is fortified heavily, it's population centres turned into massive fortress-cities not dissimilar to the Kasrs on Cadia. The Waaagh eventually arrives and breaks itself on Heavensreach's battlements.
- Envoys from nearby Ultramar visit Ulyssia, the rising star of the Eastern Fringe.
- A small crusade is conducted to the galactic east of the Gulf to bring the Harvest Cluster subsector into the Imperium. The Cluster is an independent human federation of stars pre-dating the Great Crusade. The Harvest Crusade is unsuccessful, and further attempts are not made.
- After more than a century of warfare, the Knight world Tempest is brought into the Imperium.
- The Gulf is largely unaffected by the direct conflict of Goge Vandire's Reign of Blood, but for nearly a century supplies begin to run thin as the core Imperial worlds neglect the outer colonies during the civil wars. Demand for supply forces the hand of the local Mechanicus outpost, and drives them to redouble their efforts and truly establish themselves as a power in the Gulf.
- Ravenforge is colonized and established as a full fledged forge world, and serves as the manufacture hub in the Pegasus Gulf.
- The prosperous forge world Ravenforge is abandoned seemingly overnight by the Mechanicus stationed there. The manufactorums and foundry pits go dark and quiet, and all communication and trade from the world ends.
- One of Hive Fleet Behemoth's many splinter fleets enters the Pegasus Gulf and ransacks Ulyssia. It is named Splinter Fleet Titan after its abnormal quantity of Alpha class lifeforms. Battlefleet Pegasus quarantines the Ulyssian system and declares Exterminatus on the planet after its population was consumed by the xenos. Splinter Fleet Titan is destroyed.
- The first outriders from Gargrim's fleet, lead by Bolgog the Skullkrusha, make landfall on Ulyssia and plunder what they can before moving on. Bolgog's pirate fleet evades Battlefleet Pegasus for more than a decade while harrying the trading lanes between Persephone and Heavensreach.
-Bolgog's horde launches a small scale invasion on Tempest, but is repelled by the efforts of its Knight Households.
- The stable warp rift at the heart of the Pegasus Gulf, the Hades Gate, begins to fluctuate and spasm with chaotic energy. It re-stabilizes itself within a few weeks.
- Abbadon's 13th Black Crusade is making serious headway into the Imperium. Cadia has fallen, and the Imperial Blockade of the Cadian Gate has been breached. The Imperium is diverting resources from all across the galaxy to try to bring the Crusade to a halt.
- Hive Fleet Leviathan is continuing to bore through the galactic south towards Holy Terra, and the hundreds of splinter fleets from Kraken and Behemoth are still active in the galactic east.
- WAAAGH! Gargrim enters the Pegasus Gulf from the galactic west, and pillages several frontier worlds.
- The Cadian 117th Whiteshields are redirected from the counter offensive at Mu'gulath Bay to the defence of the Pegasus Gulf.
- The Angels of Solace chapter of Space Marines arrive in the Pegasus Gulf.
- A Fourth Sphere Expansion Expeditionary Fleet arrives from the galactic north, intent on taking the agri-world Persephone as it's staging point in the Gulf. Persephone is the gateway to the entire sector from the north, and the Pegasus Gulf's breadbasket.
- The Black Waaagh makes landfall on Persephone and lays waste to the countryside.
- The Cadian 117th Whiteshields, and a combined strike force of Dark Angels and Angels of Solace prepare the defences of Persephone's only Hive City.
- Craftworld El'Doryyn mysteriously enters Persephone's orbit and offers to aid the Imperial defence.
- The Vulture Hill Massacre happens just before dawn outside the walls of Hive Persephone. The Imperial Alpha Strike Force is ambushed by thousands of orks hiding in the bayous and outside the valley as they move in to engage the Tau forward camp.
- The One Day War is fought in the streets of Hive Persephone. The Imperial defenders, Eldar, and Tau are all driven off world by the Black Waaagh. Gargrim the Black renames Persephone the Kauldron.
- Imperial forces in orbit of Persephone scatter as Gargrim's Waaaghfleet arrives in full. The majority of the Imperial Fleet, including the Astartes strike cruisers, escape towards the sector's fortress world Heavensreach to recompose themselves.
- The Imperial Battlecruiser, Resurrection, makes a miscalculated jump to Ulyssia and is struck by meteors carrying dormant Tyranid lifeforms from the thought exterminated Splinter Fleet Titan.
- The fragmented Tau Expedition Fleet retreats into the dust nebula called The Fingers to hide from Imperial patrols and ork pirate raids.
- The Big Mek Boltbrainz forms a splinter Waaagh and invades the dead world Ravenforge. His forces pillage the surface of the former forge world and build a massive tractor beam on its moon. The tractor beam pulls ships spat out of the Hades Gate into the planet's orbit or onto its surface to be salvaged for parts by Boltbrainz' mekmob.
- The Resurrection hears Boltbrainz' fake distress call and warps to Ravenforge. It is smashed to the surface with no human survivors. Primitive Tyranid lifeforms are introduced to the planet.
- The Tau Expeditionary Fleet arrives in orbit of Ravenforge to commandeer the orkish salvage operations in order to repair their own fleet and establish a permanent foothold in the Gulf.
- Craftworld El'Doryyn mysteriously arrives yet again, with unclear goals. They intend on re-purposing the ork tractor beam to close shut the Hades Gate warp rift.
- A small orkish fleet arrives under command of Bolgog the Skullkrusha to make an example of Boltbrainz.
- Tyranid lifeforms arrive on the moon base, and begin rapidly reproducing both there and on the surface of Ravenforge.
- Bolgog's forces are confronted by a Tyranid horde, lead by the legendary tyrant thought to have died on Ulyssia, the Harbinger. Bolgog retreats from Ravenforge and begins the long journey back to the Kauldron.
- The Tau Expeditionary Fleet flees back to the Fingers in light of the Tyranid threat.
- Tyranid lifeforms eventually consume all life on the moon base, and make further boarding attempts all but impossible.
- A noteable Dark Eldar slaveship appears out of the Hades Gate and is smashed into Ravenforge by the haywire tractor beam. Its crashsite reveals a sprawling Necron crypt as it collapses part of the world's surface into itself.
- Gargrim the Black and his fleet make Warp jump to Ravenforge to handle Boltbrainz himself. He arrives as the El'Doryyn Eldar stage an attack at the crash zone to sabotage the Necron tomb.. A cadre of Boltbrainz' followers are left behind to try to salvage the crashed slave ship, but are swarmed by Tyranids and Gargrim's horde. Farseer Ty'rieal himself is present at the fight and confronts a bio-titan with the legendary Thirty at his back. Gargrim murders the Harbinger in combat and escapes with many of his forces aboard their landing craft or the haphazardly repaired slaveship and return to orbit as the area is overrun by Tyranids.
- Ravenforge is abandoned to the Tyranids. Bolgog Skullkrusher and the Tankboss Wuzgob remain on Ravenforge searching for the traitor Boltbrainz. Warboss Gorezogg remains with them for a brief period of time before departing after looting one of Boltbrainz' mek shops.
- The mining colony Crucible is drawn into the fluctuations of the Hades Gate, assumed to never be seen again.
Late 003.M42 Edit
- Civil war erupts between the Knight Households on the surface of Tempest. The Imperial forces on Heavensreach mobilize to intervene.
- Over the course of the war, the Orks under command of Gargrim the Black sack Castle Gallant and discover the location of an ancient artefact they called the Hellmouth. This would become a focal point of much interest for the xenos factions in the gulf, as well as the site of several Angels of Solace strikes.
- Ultimately, the Loyalists were driven offworld, their supporters scattered to the winds, while the Secessionists crowned themselves kings of a drowned world after the Xenos left after claiming their prizes.
- Battlegroup Achilles enters the Pegasus Gulf from the Galactic West, arriving from the neighbouring Vandal Reach to lend aid. They stabilize several worlds in the lower Iron Cluster, before making landfall on Sprawl. Nineteen regiments of infantry, sixteen tank regiments, twelve artillery regiments, and half of the battlegroup's fleet vanish. The few survivors of the battlegroup muster in the colonies of the Iron Cluster and bide their time.
- Crucible is spat out of the Hades Gate, and balances between this reality and the next on the edge of a knife. Documented and undocumented missing ships are found by their hundreds on the dead surface of the planet, seemingly aged hundreds of years.
- Bolgog and Wuzgob confront and kill Boltbrainz after nearly a year of searching the ashen surface of Ravenforge, amidst ongoing hostilities between the awakening Merenrakha Dynasty and the ravenous Tyranids. They depart for the Kauldron immediately.
- The Merenrakha Dynasty awakens all over the northern Gulf, mostly among the dead worlds and helpless colonies in the Homestead Marches. Journey is particularly lively.
- Castle Gallant is transported from Tempest to the Kauldron and hovers over the massive, sprawling ork city, renamed the Black Krown.