Shielding of Helias

The Shielding of Helias was an Imperial defensive campaign conducted by both the Emperor's Reapers and their allies from the Blood of Vulkan Space Marine Chapters, alongside local Planetary Defence Forces in the defence of the Imperial world of Helias, one of the Emperor's Reapers primary recruitment worlds, against the ravages of the encroaching Tyranid Hive Fleet Temptus.

Background
As the 42nd Millennium dawned, the Emperor's Reapers primary recruitment world of Helias fell under the voracious gaze of the Great Devourer in the form of Hive Fleet Temptus, when the invaded the system. As soon as word reached the Chapter, the entirety of the Emperor's Reapers' Chapter fleet rushed to combat the threat. When the chapter arrived, large portions of the planet and the chapter launched an all-out assault, with the world's Planetary Defence Forces and another Chapter - called the Blood of Vulkan - with the allied chapter evacuating civilians and helping with the Reapers' wounded. In a 10-month conflict with the hive fleet the insatiable xenos were severally weakened and the hive fleet finally retreated, although the Reapers suffered a 15% casualty rate and would have taken decades to return to full-strength until the arrival of the Primaris Space Marines to bolster their ranks.