Even as the Heart of the Forge completed its consumption and began its advance toward the Imperial eastern defensive lines, the Orks of Octarius launched a massive invasion across the borders of the Imperium. These greenskins, having weathered the grueling war of attrition against the Tyranids, displayed combat capabilities far exceeding the Imperium's previous strategic estimates the moment contact was made.
Incalculable numbers of vessels, constructed from localized space-debris and scrap, launched synchronized assaults across multiple sectors. The sheer hull count was staggering. Worse still, the individual combat prowess of these Orks was terrifying; though the Imperial Navy had been on high alert, their battle lines were nearly overrun by the sheer weight of the xenos numbers.
Had it not been for the ancient vessels previously left behind by Axion, whose destructive output proved devastating in the opening engagements, the Imperial Navy might not have survived the initial wave. Even with such support, the Navy was forced into a fighting retreat, contracting their defensive perimeters to consolidate fire-groups. Anchoring their formations around fortress worlds and orbital battery stations, the Navy struggled to stem the tide of the greenskin onslaught.
Yet, the fanatical Orks proved almost irresistible. Among the myriad enemies of the Imperium across the galaxy, the Orks remain the most singular threat. In conventional void warfare, long-range broadsides are the primary doctrine. Even the Tyranids rely on bio-plasma, bio-pulse weaponry, and acidic sprays as their primary means of engagement. The Orks, however, possess a mania that invariably turns every void engagement into a boarding action.
The arrival of the Octarius fleets reintroduced the Imperial Navy to the most brutal form of traditional warfare. These "rokk-ships" and scrap-hulks, though crude in appearance, were exceptionally durable. Projecting thick, rudimentary void shields, the massive flotillas dove headlong into the heart of the Imperial formations, unleashing catastrophic destruction at point-blank range.
Adhering to the creed of "bigger iz betta, more iz betta an' more proppa," the Orks built their ships to massive scales, festooning the hulls with an impossible array of conduits and barrels. None could say how these haphazardly integrated weapons were powered or how their massive shells were cycled, but the firepower of these "hedgehog" ships defied all reason. The Orks crammed as many batteries as possible onto their decks, with calibers as large as their Mekboyz could forge.
Driven by the "gestalt-logic" of the Big Meks, these scrap-vessels were not only gargantuan but possessed staggering power output. Battleships that appeared to be nothing more than a chaotic jumble of riveted metal plates frequently outpaced the meticulously engineered cruisers of the Adeptus Mechanicus. Across the entire Eastern Fringe, the scene was the same: Ork kroosers plowing through Imperial lines like battering rams.
Observing the crude, iron-shod glyphs of the Orks bolted onto the hulls of these behemoths, many Navy commanders found themselves paralyzed by the tactical absurdity of the situation. Standard naval maneuvers and strategic doctrines seemed useless against such mindless aggression. The Orks appeared to have no concept of "optimal firing range." They simply opened their throttles to maximum, burying their prows into the Imperial defensive grid and unleashing "all-out" barrages that saturated the void with hyper-caliber munitions.
Should an Imperial target prove too resilient to be broken by gunfire, it was immediately swarmed by a localized eclipse of boarding craft. Scrap-built heavy lifters, assault boats, boarding torpedoes, and even pressurized metal canisters propelled by nothing more than a melta-charge and a few primitive thrusters would ferry dozens of Ork Boyz into the hulls of the Emperor's ships.
The Octarius Sector had once been consumed by Hive Fleet Leviathan, and by all rights, it should have been a dead zone. However, with the emergence of the Great Rift and the subsequent galactic upheaval, the Imperium could not afford to monitor a region beyond the galactic rim. None knew how the warlord known as Zog Steeltoof, who famously painted himself in lucky blue, had managed to drive the Tyranids back. One thing was certain: the Tyranids had left behind a massive wealth of biomass, providing the Orks with the perfect foundation for exponential fungal reproduction.
None knew how long the Orks had been festering in the dark, but their numbers had reached an apocalyptic scale. Every Ork vessel was dangerously over-capacity; the greenskins were packed into the decks like sardines in a tin. When the boarding actions commenced, the sheer volume of Ork assault craft launched often outnumbered the torpedoes fired by their own ships.
Furthermore, these veterans of the Tyranid wars were almost exclusively elites. They were a full head taller than Orks encountered elsewhere in the Imperium, and many had begun to don full suits of "eavy bitz." Though their weapons remained crude and lacked precision, their kinetic impact was devastating.
Armsmen of the Imperial Navy boarding parties found themselves outmatched and overwhelmed. The massive calibers of the "sluggas" and "shootas" could shatter a heavy boarding shield in a few bursts. Once the shield-wall was breached, an entire corridor of sailors would be reduced to a slurry of gore by heavy rounds comparable to bolt shells.
"WAAAGH!"
The exhilarated roars of the greenskins echoed through the decks of every contested ship. As the Navy defenders were slaughtered, the Orks moved to claim their "looted" prizes. Big Meks and their retinues of Spanna Boyz worked with frantic speed, using slabs of salvaged steel to patch the boarding breaches. The Imperial Aquila was defaced and replaced with crude, welded iron Ork glyphs. Some even retooled the decorative prow statuary into idols of Gork and Mork.
Within hours, these captured vessels were turned back against the Imperium. In response, the various Space Marine Chapters arriving as reinforcements adjusted their tactics. Adeptus Astartes squads were distributed across the Imperial fleet to serve as elite counter-boarding units, meeting the greenskin tide with chainsword and bolter.
Even the Carcharodons, a Chapter that rarely participated in the Imperium's conventional theaters of war, arrived at the defensive line. Not only did they bring their own cold fury, but they returned a hero to the Black Templars already fighting there: their Emperor's Champion, Thien.
Following the Carcharodons' ambush of Abaddon's Balefleet in the Ghoul Stars, the Space Sharks had purged every heretic and traitor aboard, reclaiming vital materiel from the wreckage. When the Carcharodons boarded a particular Chaos battleship, they found only a landscape of severed limbs and congealed blood. Deep within the vessel's sanctum, they discovered Thien, unconscious but alive.
The Carcharodons' Techmarines, analyzing the jagged wounds on the traitor remains, confirmed that nearly every heretic had fallen to the strokes of a Black Sword. The Apothecaries assisted in recovering the gene-seed of thirty other Sons of Dorn from the wreckage before bringing the comatose Champion back. Though the Carcharodons are a brutal and isolated Brotherhood, they hold strength in high regard. A warrior who could carve his way through an entire Chaos battleship alone and survive was, without question, a master of death.
As for the Black Sword of the Emperor, the Carcharodons looked at the legendary lightning claws, Hunger and Slake, wielded by their Chapter Master, Tyberos the Red Wake, and concluded that the blade did not suit their particular style of carnage.
After all, they were not the Blood Ravens.