Tyran - First Contact: 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 Aeldari 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 solar 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 Mechanicus 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 solar 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 provided 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 cybernetic 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 Astra Militarum.This was a standard garrison for a valued 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.