Onyx Conflict

Introduction
The Battle of Onyx was a heavy, prolonged military engagement between the Forerunner Sentinels, United Nations Space Command, and the Covenant.

Sentinel Activation
When Delta Halo's firing sequence was interrupted, it emitted a signal that placed all other Forerunner installations in standby mode, including the Sentinels guarding the Shield World 'disguised' as the 'planet' of Onyx. On October 31, 2552, the first of these Sentinels to awaken suddenly began attacking UNSC forces on or near Onyx. Coincidentally, Gamma Company was participating in the Top Honors exercise at the time.

Almost immediately, Team Gladius and the orbiting were destroyed and Team Katana captured. Team Saber regrouped with Kurt-051, Tom-B292, Lucy-B091, and Chief Mendez, although they had no means of summoning reinforcements from the rest of the UNSC.

Dr. Halsey, Kelly-087, and AI Jerrod arrived aboard Beatrice. Attacking Sentinels forced the ship to crash land on the planet, although all three passengers survived to link up with Kurt-051's group. Halsey proceeded to convince the resident ONI AI, Endless Summer, to send a distress message to the UNSC using the Slipspace COM Launcher. In the signal Halsey requested the deployment of SPARTAN-II's to Onyx. The launcher was destroyed shortly after firing.

The message succeeded in reaching a besieged Earth and diverting Blue Team to Onyx. However, en route the message had been intercepted by the Covenant. Newly promoted Fleet Master Voro Nar 'Mantakree of the Second Fleet of Homogenous Clarity was deployed to Onyx under orders to destroy all UNSC forces and recover any Forerunner artifacts.

Blue Team and the Covenant Arrive
Blue Team, composed of Will-043, Linda-058, and Fred-104 arrived at Onyx aboard the commandeered Bloodied Spirit, but were forced make their way down to the surface in a Spirit when their ship was attacked by Sentinels. Linking up with Kurt-051's group they planned to attack Zone 67. Using the Spirit they flew into a crater and discovered a Forerunner city.

In the same time, 'Mantakree force, formed around Incorruptible, began nearing Onyx. Far Sight Lost was sent ahead to scout the environs but was quickly engaged and destroyed by Sentinels. Another scout, Absolution, was ordered to perform a precision slipspace jump to the northern polar areas of Onyx, but the Sentinels followed it through slipspace and Absolution was destroyed upon exiting slipspace. However, sufficient information had been gathered and 'Mantakree ordered his ground troops to converge on Zone 67.

Battlegroup Stalingrad
The UNSC Dusk, a Prowler, arrives at Onyx via slipspace in the wake of the In Amber Clad after Voro engages the Sentinels. Shortly thereafter, Admiral Patterson arrives with Battle group Stalingrad intending to catch the Covenant off guard. The battle group finishes off several Covenant destroyers using  Archer missiles, MAC rounds, and various nukes. A single destroyer survives, and fires at the UNSC  Stalingrad, the flagship of the battle group where Admiral Patterson was commanding from. The battle group launches MAC rounds to finish the ship and the UNSC  UNSC Glasgow Kiss puts itself between the Stalingrad and the plasma fire. A dozen escape pods popped from her hull and caught three of the four lances of fire.

The Covenant destroyer takes multiple hits and flees to the other side of Onyx, leading the UNSC battle group into a trap of twenty Covenant warships. The UNSC ships manage to take out several destroyers, but the Covenant launches a massive volley of plasma. The UNSC ships accelerate into the attack in hopes of emerging too close for a second volley. Five ships survive the volley, of which one, the UNSC UNSC Iwo Jima, crashes into several enemy ships, taking two out and damaging six others in the resulting explosion. The other four manage to flee to the other side of Onyx. The Sentinels choose this time to attack the Covenant fleet, destroying an additional three destroyers by using Plasma capture and buying the UNSC ships time to retreat and regroup. The Covenant ships attempt to retreat from the gravity of Onyx, using two ships as decoys while the rest pull back. One of the rear guard ships was also blasted to atoms by the Sentinels

The UNSC prepare to engage the Covenant ships again. The Dusk lays a HORNET nuclear minefield—thirty-megaton yield with vacuum enhanced loads—on either side of Onyx’s moon. The UNSC battle group then fire from behind the moon at the Covenant ships to get their attention; three Covenant ships are hit, but remain undamaged. As the Covenant ships enter the mine fields, the Dusk detonates the 14 HORNET mines and destroy twelve of the sixteen Covenant ships. Admiral Patterson maneuvers his four ships in and finish off two of the wounded Covenant ships immediately. The other two Covenant ships traveled around the moon, and as they come back to face the remaining UNSC ships, a Covenant armada of thirty-two ships jumps from slipspace, and utterly destroy Admiral Patterson’s remaining ships with the exception of the UNSC Dusk.

Retreat to the Shield World
While the UNSC and Covenant fleet fought in orbit, a firefight between Covenant forces and Kurt-051’s forces in the Forerunner city ensues. Kurt-051, Fred-104, Linda-058, and several Spartan-IIIs try to hold the Covenant back while Halsey tries to configure a teleportation grid for them. Kelly-087 and Mendez are with Halsey. Dante-G188 is killed while rescuing Fred-104 by plasma and Needler fire. AI Endless Summer contacts Halsey and Kurt-051, telling them they need to destroy the Sentinel Production Facility in order to save Battlegroup Stalingrad. Halsey gets the teleportation grid working, and they all teleport to the Sentinel Production Facility near the northern pole in Onyx. Halsey sends them to destroy three key structures, which would bring the entire production to a halt. Using the teleportation grid, they go to the three structures and trick Sentinels into firing on them on a line with the structures. Having destroyed the structures, they teleport back.

Kurt-051 and his team arrive at Team Katana’s holding area to find them in some sort of cryo-slipspace containment cells. There are eight such containers, five of which contain Spartan-IIIs. They travel to the Core Room Antechamber, where they prepare to hold off a Covenant invasion force from a small tower. The Covenant have three Hunter pairs, Elites from the E’Toro, R’Lan, and N’Nono warrior crèches, and plenty of other troops. First, they send two hundred Grunts to distract Kurt-051 and company, while Elites set up stationary shield generators. There were three groups of thirty Elites and one Hunter pair behind each shield. The Elites form a line and advance behind Jackal shields. Kurt-051’s group used grenades and  snipers to counter. When the Elites and Hunters approach the stairs, Kelly-087 detonates LOTUS mines placed on the first step, killing several Elites and dazing two Hunters. Kurt-051 kills one Hunter, but the other manages to duck behind its shield. Kelly-087 engages three sword-wielding Elites, killing all three, but is flanked by two Hunters. Holly-G003 sacrifices herself to save Kelly. Kurt rushes forward and a Hunter slashes him with its shield. Linda-058 puts a round into the Hunters midsection, and then Will-043 engages them both in hand-to-hand combat. He kills one, but the other shoots him which resulted in the death of Will-043. Fred-104 kills the second with a well placed Jackhammer missile.

The Covenant forces pull back. Hundreds of Elites, Banshees, and Grunts prepare for the main assault. Kurt-051 orders all other personnel through the core and into a Micro Dyson Sphere. Kurt-051 stays behind, and after the rift closes, the Covenant approach. Voro approaches, intending to kill Kurt-051 and then reopen the rift, when Kurt-051 detonates the two FENRIS nukes, killing himself, Voro, and the entire Covenant force in the Core Room Antechamber. The others that went through the portal were not harmed, but put into a massive forerunner safe heaven that could protect the from them the covenant and halo activations.

Results
The entire Covenant Force is destroyed when Onyx is revealed to be built atop trillions of Sentinels, which promptly open fire on the covenant fleet to protect the mini Dyson Sphere inside a slipspace warphole in the middle of Onyx. The "Dusk" escapes before it, too, is obliterated.

Space

 * Human
 * Fleet Admiral Sir Terrence Hood
 * Admiral Carl "Buster" Patterson
 * Vice Admiral Danforth Whitcomb
 * Commander Richard Lash
 * Lieutenant Joe Yang
 * Lieutenant Commander Julian Waters
 * Lieutenant Commander Xaing Cho
 * Lieutenant Bethany Durruno
 * Lieutenant Junior Grade Fred SPARTAN-104
 * Petty Officer Second Class Will SPARTAN-043
 * Petty Officer Second Class Linda SPARTAN-058
 * Covenant
 * Xytan 'Jar Wattinree
 * Voro Nar 'Mantakree
 * Uruo 'Losonaee
 * Zasses 'Jeqkogoee
 * Y'gar 'Pewtrunoee
 * Ship Master Qunu
 * Kwassass

Ground

 * Human
 * Lieutenant Commander Ambrose / Kurt SPARTAN-051
 * Lieutenant Junior Grade Fred SPARTAN-104
 * Senior Chief Petty Officer Franklin Mendez
 * Petty Officer Second Class Will SPARTAN-043
 * Petty Officer Second Class Linda SPARTAN-058
 * Petty Officer Second Class Kelly SPARTAN-087
 * Petty Officer Second Class Lucy SPARTAN-B091
 * Petty Officer Second Class Tom SPARTAN-B292
 * Petty Officer Second Class Holly SPARTAN-G003
 * Petty Officer Second Class Ash SPARTAN-G099
 * Petty Officer Second Class Dante SPARTAN-G188
 * Petty Officer Second Class Olivia SPARTAN-G???
 * Petty Officer Second Class Mark SPARTAN-G???
 * Dr. Catherine Elizabeth Halsey
 * Endless Summer AI#4279
 * Jerrod "Micro AI"
 * Covenant
 * Voro Nar 'Mantakree
 * Paruto Xida Konna
 * Waruna Xida Yotno

Ships
UNSC Covenant
 * Battlegroup Stalingrad
 * , Carrier
 * , Destroyer
 * , Destroyer
 * , Destroyer
 * , Prowler
 * Beatrice, modified
 * Beatrice, modified
 * Incorruptible,
 * Sublime Transcendence, Covenant Supercarrier
 * Absolution, Covenant CPV-class
 * Bloodied Spirit, Covenant CPV-class
 * Far Sight Lost, Covenant CPV-class