Onyx Conflict

This article is about the battle during the Human-Covenant War. For the battle in 2558, see Second Onyx conflict.

This article is no longer up to date and needs to be updated with new information from Halo: Glasslands, Lessons Learned and Halo: Legacy of Onyx. You can help by updating this article.

Previous:	Battle of New Mombasa
Concurrent:	Battle for Earth Battle of Installation 05 NOVA bombing of Joyous Exultation
Next:	Defense of Mars
Onyx Conflict
Conflict:	Human-Covenant War Great Schism
Date:	October 31-November 3, 2552
Location:	Onyx, Zeta Doradus system
Outcome:	Forerunner constructs victory Some UNSC forces escape Onyx disintegrates into trillions of Sentinels All Covenant forces destroyed Sarcophagus shield world sealed with some survivors inside
Details Belligerents UNSC Covenant separatists Joyous Exultation Covenant Forerunner constructs Commanders ADM Carl Patterson† LCDR Kurt Ambrose† Fleet Master Voro Nar 'Mantakree† Unknown Strength Space Battle Group Omicron 1 carrier 1 Marathon-class heavy cruiser 6 destroyers 1 prowler UNSC Agincourt (frigate) Ground 5 Spartan-IIs 17 Spartan-IIIs Several ONI agents 54 Covenant warships Second Fleet of Homogeneous Clarity 22 ships 1 heavy cruiser 1 carrier 2 cruisers 18 destroyers Combined Fleet of Righteous Purpose 32 ships Multiple carriers Multiple cruisers Multiple destroyers Legions of Covenant warriors Six Mgalekgolo Over two hundred Sangheili Thousands of Unggoy Banshees Seraphs Trillions of Sentinels Sentinel manufacturing facility Casualties Battle Group Omicron save for UNSC Dusk UNSC Agincourt (frigate) Will-043 Kurt Ambrose Dante-G188 Holly-G003 Team Gladius An unknown number of ONI personnel All Covenant ships All ground forces Voro Nar 'Mantakree Thousands of Sentinels Sentinel manufacturing facility

The Onyx Conflict was a military engagement between the Forerunner Sentinels of the planet Onyx, the United Nations Space Command, and a fledgling Covenant splinter group. The UNSC operation to reinforce the stranded UNSC forces on Onyx was codenamed Operation: CIRRUS.

Battle

The Sentinel activation

When Alpha Halo was almost activated, it emitted a signal that placed all other Forerunner installations in standby mode, including the Sentinels guarding the shield world located within the artificial world of Onyx. The Sentinels themselves first appeared on the morning of September 21, 2552. On October 31, 2552, the first of these Sentinels to awaken suddenly began attacking UNSC forces on and near Onyx. Coincidentally, Gamma Company was participating in the top honors exercise at the time.

Almost immediately, Team Gladius and the orbiting UNSC Agincourt were destroyed and Team Katana lost after passing to Zone 67. The SPARTAN-III trainers, save for SCPO Mendez and Kurt Ambrose were all killed as well. In accordance with emergency protocols, Zone 67's AI Endless Summer assumed complete command of all UNSC forces on Onyx. Shortly afterward, Team Saber regrouped with Kurt-051, Tom-B292, Lucy-B091 and SCPO Mendez, although they had no means of summoning reinforcements from the rest of the UNSC. Mendez declared