Changes

The first indication of the Tyranid thread was silence across much of Segmentum Pacificus as the [[Shadow in the Warp]] descended. The loss of communication with many outlying [[System]]s initially went unnoticed by several [[Sector]] commands due to the typically slow wheels of Imperial bureaucracy, the presence of [[Warp Storm]]s, as well as simultaneous [[Ork]] and [[Knydd]] threats. The scale of the threat was finally discovered in the [[Morpheum Sector]] command thanks to the horrific death of High [[Astropath]] [[Guideoth]]. Consumed by the Shadow in the Warp, the Astropath was transformed into a tendrilled monstrosity that wrought destruction across the [[Astropathic Choir]] before finally being put down. Simultaneously, reports finally began reaching Imperial authorities of a Tyranid attack of unprecedented scale. The [[Byroth Sub-sector]] was consumed by Tyranids as its [[Imperial Guard]] forces battled Orks. At the [[Trinary Reach Cluster]], a [[Leagues of Votann]] fleet suddenly retreated as the Imperial defenders of several factory worlds rejoiced, only for the Tyranids to descend in their wake. Vast refugee fleets began arriving in the [[Haratus Stars]], the [[Mytolian Belt]], [[Templum II]], and [[Gethsemanax]]. Despite security precautions and quarantines, Tyranid xenoforms and spores still got through and caused [[Genestealer Cult|bloody uprisings]] in the aftermath.{{Fn|24a}}

Gradually, Imperial commanders were able to put together a horrifying picture. Two new tendrils of Hive Fleet Leviathan of unprecedented size had invaded Imperial space in a coordinated effort. One, dubbed [[Hive Fleet Nautilon|Nautilon]], was moving into the [[Vynor Sector]] from above the galactic plane while the other, dubbed [[Hive Fleet Promethor|Promethor]], was moving into the [[Morpheum Sector]] from below it. Worse still, these two tendrils were coordinating with one another in a roughly paralleled eastern advance. If It was a route that, if unaltered, would take them into [[Segmentum Solar]] and towards Holy [[Terra]] itself. The Imperial response to this horror was typically inconsistent, with some [[Governor]]s oversee total mobilization to conduct a defense while others simply led a mass abandonment. Some [[Space Marine]] and [[Imperial Navy]] elements sought to wage whatever defense they could while other [[Astra Militarum]] armies began to attempt to create defensive lines to stem the Xenos advance.{{Fn|24a}}