Gaze of the Basilisk

The Gaze of the Basilisk was the name of the joint-Imperial defensive campaign to protect the worlds of the Segmentum Ultima from the encroaching threat of the Tyranids of Hive Fleet Basilisk. This was one of the first recorded campaigns conducted by the newly incepted Star Wardens Space Marine Chapter, a Ultima Founding Successor Chapter of the Ultramarines comprised entirely of Primaris Space Marines.

Background
In one of their first notable engagements, the Star Wardens were dispatched by Guilliman to halt a rampaging splinter fleet of Leviathan codenamed: Basilisk. The Star Wardens positioned their fleet ahead of the hive fleet, waiting in ambush. As the bioships of the Tyranids approached the guns of the star fortress Imperial Sovereign roared their contempt and taunted the vile xenos to approach. The Tyranids were swiftly lured closer to the star fortress and the ships of the Star Wardens fleet descended from both flanks catching the Tyranid swarm in a vicious crossfire.

Tyranid bioships began to implode under the withering Imperial firepower, and the Star Wardens ships expertly threaded their way through the midst of the swarm. Unleashing great broadsides as they divulged boarding teams of astartes. One by one the bioships were destroyed from the inside and the hive fleet soon disintegrated in a resounding Imperial victory. The battle demonstrated the Star Wardens skill at void combat, and several members of the chapter were seconded to the Deathwatch afterward.