Event · M41
First Tyrannic War
The First Tyrannic War was the Imperium of Man’s first major conflict with the Tyranids, fought chiefly in Ultramar in the forty-first millennium. It is recorded as beginning in 745.M41, when Hive Fleet Behemoth entered the eastern reaches of the galaxy and its advance was first identified by Imperial authorities. The war takes its name from the Tyran system, where the invaders were first catalogued, and the species was afterwards designated Tyranid. Accounts differ on the precise sequence of early contacts, but the fleet is held to have consumed a succession of outlying worlds before turning toward the realm of the Ultramarines. The decisive phase took place in the Ultramar realm, whose capital world is Macragge, the home of the Ultramarines Chapter of Space Marines. The Chapter, then led by Chapter Master Marneus Calgar, mustered its forces and those of the Imperial Navy and planetary defence to meet the invasion in orbit and on the surface. Fighting centred on the approaches to Macragge and on its fortified strongholds, including the Fortress of Hera, where the Ultramarines and their allies contested the Tyranid landings. The Chapter is recorded as suffering severe losses, and the defence is remembered as one of the gravest tests of Ultramar since the Horus Heresy. The war ended with the destruction of Behemoth’s main body at Macragge in 746.M41, and the Imperium claimed a victory that preserved Ultramar. The consequences were lasting: the Ultramarines spent years rebuilding their numbers, and the surviving fragments of the fleet are held to have scattered and continued to threaten the eastern fringe. The conflict established the Tyranid threat in Imperial records and preceded the later Tyrannic Wars, in which other hive fleets returned to the same region. On Orrery, the war anchors the Behemoth entry on the timeline to Macragge and Ultramar on the map, and it is best read alongside the Ultramarines, Marneus Calgar and the Tyranids themselves.
See where First Tyrannic War occurred on the galactic map in the 41st Millennium.