The engagement taking place in the orbit of Chi Ceti IV between the UNSC UNSC Commonwealth and the Covenant light cruiser Unrelenting was one of the earliest, and perhaps also one of the smallest naval engagements to occur between Covenant and UNSC forces. When the Covenant attacked, the SPARTAN-IIs boarded their ship and succeeded in destroying it, but Samuel-034 died in the process, the first Spartan to be listed as MIA.
The Mjolnir Powered Assault Armor/EOD variant and the Soldier variant of the Mjolnir Powered Assault Armor (GEN2) were also developed at the Damascus facility in this system. Thus meaning it was reoccupied by the UNSC during or after the Human-Covenant war.
- A planet from Bungie's previous game, Marathon, takes a similar name, Tau Ceti IV.
- Tau Ceti IV was also where the Mjolnir Mark IV Cyborgs revealed themselves in Marathon.
- One of Chi Ceti's moons, Muroto, was home to the Materials Group mining facilities.