"We cannot live through this. Mankind cannot live through this. In a single day they have covered this planet with a flood of living blades and needle-fanged mouths. Kill one, and ten take its place. If they are truly without number, then our race is doomed to a violent death before every shred of our civilisation is scoured away by a force more voracious than the fires of hell themselves. Death! By the Machine God, Death is here!"
- — The last words of Magos Varnak
Tyran, or more formally Tyran Primus, is the former Ocean World on the very edge of the Milky Way Galaxy in the Eastern Fringe where the Adeptus Mechanicus of the Imperium of Man maintained a small research outpost. It was on Tyran that Mankind made first contact with Hive Fleet Behemoth, which destroyed all life on the planet in early 745.M41 and initiated the First Tyrannic War. Tyran is now classified as a Dead World by the Administratum, the first of many in Imperial space created by the Great Devourer. The encounter at Tyran gave a name to this deadly new threat to all life in the galaxy, a terrifying xenos species known only as the Tyranids forever after.
The first recorded contact between the Imperium of Man and the Tyranids occurred in early 745.M41 on the Eastern Fringe of Imperial space. To that point, Imperial records indicate that Mankind was wholly ignorant of the terrible new threat that was emerging from the intergalactic void and if any of the galaxy's older intelligent species like the Eldar were aware of the Tyranids' existence, they had never deigned to warn Mankind of the terror that was to come. Yet Hive Fleet Behemoth had left plenty of evidence of its approach to the fringes of the Milky Way Galaxy. Over the course of the decade that preceded the first contact at Tyran, Imperial Explorators had performed a census of the star systems surrounding the far-flung Adeptus Mechanicus outpost located at Tyran Primus. These Explorators had discovered something curious, for entire worlds known to once have been verdant planets teeming with all manner of alien animals and plants had been stripped bare, reduced to barren rocks floating in the vacuum. Not one speck of life, not even the simplest of bacteria, remained to be found. Though this anomaly was reported to the Explorator General of the Adeptus Administratum, no follow-up was ordered. The galaxy is a place larger than a single human mind can comprehend and untold and unsolved mysteries abound. As always, the Administratum was as slow as only a galaxy-spanning bureaucracy can be.
As the Mechanicus outpost on Tyran continued to file reports of its discovery of a large cluster of Dead Worlds, Hive Fleet Behemoth drew ever closer. The Tyranids had to that point consumed only isolated planets that were home to no intelligent life forms, using the biomatter they absorbed to replenish the reserves the Hive Fleet had expended during the long journey through the extragalactic night. Now refreshed and replenished in number by the new stocks of organic materials, the xenos descended upon Tyran Primus. This was only the first of the Imperium's worlds to fall to the Great Devourer but would be the place from which Mankind would name this new threat to its continued existence. That the outpost on Tyran had any warning at all of the impending attack was only due to good fortune. A survey starship, returning from a survey of yet another Dead World, encountered a cloud of unidentified objects as it entered the edge of the Tyran System. Though crippled by what seemed to be mines made of organic tissue on the very edge of this cloud, the Explorator vessel managed to limp back to the Imperial base in orbit of Tyran Primus and carry its dire warning. Several days later, the first full invasion of an Imperial world by a Tyranid Hive Fleet began.
Yet the main outpost on Tyran Primus would not fall easily to the extragalactic predators. Located deep within the ruins of an ancient chain of volcanic islands, the Imperial base was heavily fortified to resist the fearsome storms and massive sea creatures of the Ocean World's savage seas. Also, given Tyran's position on the very edge of Imperial space in a very dangerous and unexplored frontier region of the galaxy, Tyran had been wisely provide with armament deemed adequate to deter the attacks of raiders or aggressive xenos. Four giant planetary defence lasers protected the Tyran outpost, each protected in turn by hardened Ceramite silos and Void Shield generators. The amount of firepower was further supported by 36 Autocannon and Lascannon interceptor emplacements, an overlapping network of defence bastions and Proteus-class bunkers. The Imperial garrison deployed on Tyran Primus was also formidable. In addition to the Skitarii bodyguard of the outpost's Adeptus Mechanicus commander, Magos Varnak, Tyran boasted 3 full wings of the Imperial Navy's Thunderbolt fighters, 3 Endeavour-class Light Cruisers and an entire infantry regiment of the Imperial Guard. This was a standard garrison for an Imperial frontier outpost and had been proven to be effective against most of the adversaries faced by isolated Imperial troops on the galactic rim. Yet against the Great Devourer, this garrison would prove to be little more than a brief obstacle to its endless hunger.
Tyran's planetary defence lasers opened fire on the foe the moment the first alien bio-ships entered orbit over the Ocean World. For more than an hour, the perpetually stormy skies of Tyran were ruptured again and again by coloured blasts of coherent light as the base's gunners desperately sought to drive back the descending xenos invaders. Then, just as the defence lasers had begun to glow white hot and overheat from the sheer number of targets, the invaders suddenly withdrew.
Buoyed by overconfidence in his own forces and ignorant of the true scope of the threat, Magos Varnak ordered his small fleet of Imperial Navy Cruisers to harry the withdrawing bio-ships, but this strategy proved to be misguided. After penetrating the spore cloud that masked the sheer size of the approaching alien fleet, the pursuing Imperial starships discovered that less than a dozen of the strange organic spacecraft had been destroyed out of the thousands present in the fleet that had entered the Tyran System. Having successfully lured the Imperial Cruisers away from the support of the planet's defence lasers, the bio-ships suddenly changed direction and fell upon the Imperial vessels like hungry sharks. The Emperor's Fist was the first Imperial starship destroyed, its hull shredded by a voracious swarm of organisms vomited forth by a much smaller vessel. The Righteous Destiny did not last much longer as a cluster of grasping tentacles dragged it into the gaping maw of a Hive Ship. Only the Sword of Warriors lasted long enough to transmit a warning by Vox to Tyran. Before the message was completed, leech-like pseudopods gnawed through the starship's Adamantium hull plates and unleashed a horde of vicious Genestealers onto the spacecraft's bridge and lower decks. The entire crew was viciously executed within minutes and the Cruiser was left to drift in space unmanned, its precious biomatter already dissolved into the Hive Fleet's reserve stocks.
With the Imperial Cruisers lost, the Hive Fleet then returned into orbit of Tyran and this time the Imperial defences proved inadequate. Thousands of Mycetic Spores hurtled down onto the world, and though the defence lasers managed to still destroy many of the lethal pods, countless more crashed into the stormy seas. All around the Imperial outpost, the waters boiled as the invaders burst from the spores and tore their way through the powerful maritime predators of Tyran's oceans, who were no match for the savagery of the Tyranids. Then the xenos scaled the walls of the Imperial outpost. At first, disciplined volleys of laser fire from the Imperial Guardsmen managed to drive the voracious creatures back, as amongst their numbers were veteran Guardsmen from the jungle-covered Death World of Catachan, long-used to battling the similar monstrous fauna of their own homeworld. The Guardsmen fought through the constant, pouring rain and their firepower scythed out massive holes within the alien line. The hides of the smaller bioforms offered little protection from concentrated laser fire and were no match at all for the Autocannons of the interceptor grid erected around the base. Wave after wave of Hormagaunts and Genestealers were torn apart and their corpses began to choke the carefully laid-out killing zones that lay between the outpost's bastions. Thunderbolt fighters soared through the skies above the base, destroying any incoming spores with precision fire before darting away to find new targets. And there were always more targets...
But the Imperial defence began to crack when the northern planetary laser finally fell silent. Thousands of Gargoyles had thrown themselves on the Hive Mind's order into its barrel, clogging the gigantic beam projectors with their own blackened bodies. Moments later the eastern planetary laser was destroyed when a Carnifex penetrated its steel walls and ripped apart the massive weapon's coolant lines. Despite their valiant efforts, the Thunderbolts eventually fell from the skies, their engines choked by spores or their pilots torn shrieking from their cockpits by Harpies. As the Imperial defence network collapsed, the Mycetic Spores began to fall onto the outpost itself.
The Behemoth Triumphs
Only an hour after this, the Imperial outpost on Tyran Primus had been effectively overrun. The bastions had been destroyed or overrun and all of the planetary defence lasers had gone silent. Even the Catachan Jungle Fighters of the Imperial Guard had finally abandoned their posts and fled into the rain in hope of an escape from a gruesome death that could not be found. Only the command bunker still stood and its walls began to crack under the impact of massive blows from some of the larger Tyranid bioforms. Through the few remaining displays that were still functional, Magos Varnak saw the unstoppable tide of xenos destroying his once-impregnable outpost. Once the Adamantium gate of the bunker crashed inwards, the Tyranids poured into the command bunker. Imperial Guardsmen and cybernetic Skitarii fought with Flamers and in some case their bare hands, but the sheer number of vicious aliens managed to hack and bite and claw their way forwards. As Hormagaunts poured into the command centre, Varnak whispered his last prayer to the Omnissiah and triggered a special switch that sent a data-codex plummeting into the depths of what remained of the outpost before being torn apart.
The precious data within this codex would prove to be the Tyran outpost's greatest legacy, for its video, pict and data records of the first Tyranid assault would be found almost a full Terran year later by Inquisitor Kryptman, a man who would later dedicate his life to ending the Tyranid threat to humanity. Without Kryptman's arrival, the fate of the Tyran outpost might never have been known and the Imperium taken completely unaware of what was to come. Kryptman had found a sterile, dead planet that now bore no sign of the thriving Ocean World it had once been. The planet had been literally sucked dry and scoured of all life, with every scrap of vegetation and even all of its water consumed by the Hive Fleet as needed biomass and nutrients. As Kryptman reviewed the data-codex he found in the outpost's ruins, the full horror of the first Tyranid attack was revealed to him. The Inquisitor immediately left the ghosts of Tyran behind to warn the galaxy of the Great Devourer's approach, a terror that Kryptman named the "Tyranids" after the first Imperial world they had consumed.
The nightmare of the Tyrannic Wars had begun, and the Imperium of Man would never be the same...
- Codex: Tyranids (3rd Edition), pp. 6-8
- Codex: Tyranids (4th Edition)
- Codex: Tyranids (5th Edition), pp. 8-9
- Planetstrike (5th Edition), p. 54