The Battle of Chi Ceti (later referred to as the Chi Ceti Incident) was fought between the UNSC and the Covenant early in the Human-Covenant war. Though it was a small scale engagement it marked the culmination of the SPARTAN-II Program with the supersoldiers being united with the MJOLNIR Mk. IV Powered Assault Armor, and the combat debut of the potent combination.
- Main article: First Battle of Harvest
The Covenant attack on Harvest, and the beginning of the Human-Covenant war, instigated a UNSC-wide mobilization. The need to deploy Project MJOLNIR took on greater urgency. The SPARTAN-IIs were sent to the Damascus Testing Facility on Chi Ceti IV aboard the frigate UNSC Commonwealth to undergo final integration with the armor. Doctor Catherine Halsey accompanied the supersoldiers to oversee the process.
Commonwealth entered the system at 1750 hours, November 27, 2525. The frigate detected the Covenant light cruiser Unrelenting as an intermittent sensor ghost at 80 million kilometers. This was far beyond the frigate's weapons range and Captain Wallace saw no need for concern. However, Doctor Halsey warned of a possible enemy tactical Slipstream jump and the captain brought the ship to general quarters. The Spartans readied a Pelican and prepared to disembark.
Halsey's warning was prescient. Unrelenting suddenly appeared 3000 kilometers from Commonwealth and opened fire with pulse lasers. The frigate's communications dish was destroyed and its AI disabled. Commonwealth returned fire with 180 Archer Missiles; the light cruiser evaded half and the remainder failed to penetrate the shields. Unrelenting destroyed the frigate's navigation dish and caused further damage with lasers. In turn, a heavy MAC round penetrated the light cruiser's shields and struck its hull directly. The round crumpled the nose of the ship and caused some internal fires.
As Commonwealth prepared another heavy round, Unrelenting charged a Plasma Torpedo. Both fired nearly at once, and struck their targets. The frigate vented atmosphere to prevent the torpedo from causing catastrophic damage but the MAC gun was destroyed. The Covenant ship likewise survived the second MAC round but had a hole punched right through it.
Commonwealth's remaining option were three Shiva-class Nuclear Missiles, however the range was too short for those to be used safely. John-117 assessed the enemy's psychology and concluded the Covenant ship was likely to stop and engage any challenge. Wallace ordered Longsword Squadron Delta to occupy the light cruiser and launched a Shiva. In the meantime the frigate came about and executed a burn away toward Chi Ceti IV. The nuclear warhead destroyed the Longswords and further damaged Unrelenting. The light cruiser subsequently disengaged.
Commonwealth made a fly by of the planet. The Spartans and Dr. Halsey disembarked by Pelican and made for the Damascus Testing Facility. The frigate retreated to 20 million kilometers to effect repairs. Pursuant to his orders, Wallace was prepared to use his damaged ship to lure the enemy away from the facility.
The battle resumesEdit
Although UNSC Commonwealth hoped to rendezvous in orbit with the SPARTAN-IIs no later than 1900 hours, the supersoldiers were just finishing the 15 minute elevator ride down top the Damascus Testing Facility at 1845 hours. Nonetheless, the Spartans were familiarized with and issued the MJOLNIR Mk. IV Powered Assault Armor without incident; they prepared to return to the surface with Dr. Halsey and the facilities few remaining personnel for extraction.
The Covenant were not yet out of the fight. The UNSC frigate detected Unrelenting moving on an intercept course through normal space. Commonwealth's Slipspace drive and MAC were offline. The Covenant vessel was also damaged but still capable of twice the speed of its opponent.
UNSC forces resolved to fight rather than run. The Spartans and company departed in the Pelican for the frigate. En route, John-117 learned the MJOLNIR armor was EVA-capable and proposed a boarding action. The Spartans would fly out from the Pelican with thruster packs and intercept Unrelenting as the ship moved to engage Commonwealth. Once aboard they would demolish the enemy ship from within using warheads from the dropship's 32 ANVIL-II Air-to-Surface Missiles. Each Spartan received one warhead.
Commonwealth fired another salvo of Archer Missiles to draw attention and fire from the approaching Spartans. The firing of Unrelenting's pulse lasers briefly lowered a part of the ships shield and allowed John-117 to grab hold. Ultimately only three Spartans, John-117, Kelly-087, and Samuel-034, made it to the hull breach caused by the frigate's MAC fire.
The Spartan trio passed through pressure doors into still-habitable sections of the ship. They fought two Kig-Yar as they homed in on a radiation source. Sam-034's armor was breached by plasma fire and was no longer EVA-capable. The radiation source was from a large chamber; a cylinder with a red pulsing light along its length ran the length of the chamber. The Spartans planted their warheads by the chamber with a three minute countdown. Unable to reenter vacuum, Sam-034 remained behind and guard the warheads; he was the first Spartan to die in combat. John-117 and Kelly-087's escape was delayed as they waited for a pulse laser to fire and create an opening in the shield; they barely escaped Unrelenting's destruction.
- This is the first conflict in which Spartan-IIs wore and used the MJOLNIR armor in battle.
- In the game Halo Wars, set in 2531, sometimes when a Spartan kills an enemy, they can be heard saying "for Samuel!," which is a direct reference to Sam's death aboard the Covenant ship in Halo: The Fall of Reach.
- The Commonwealth's success in inflicting damage in this battle inspired Admiral Cole to have his ships fire everything at once at the lone Covenant ship in the Second Battle of Harvest which resulted in the enemy ship's destruction.
- Halo: The Fall of Reach (First appearance)
- Halo: Ghosts of Onyx (Mentioned only)
- Halo Wars (Mentioned only)
- Halo Wars: Genesis (Mentioned only)