Battle of Installation 04

The Battle of Installation 04 was the name given to a series of skirmishes between the forces of the UNSC and the Covenant.

In the latter part of the battle, the UNSC and Covenant were joined in battle by the Forerunner Sentinels and Flood.

Fleeing Pillar of Autumn
Following the disastrous defeat at Reach and the loss of a third of her tech staff, the UNSC Pillar of Autumn made an apparently blind jump, but possibly planned by the AI Cortana, slipspace jump, from where they would then make their way to Earth. The Pillar of Autumn and the approximately 1,100 humans on it were followed and, upon arriving in orbit of the planet Threshold, were intercepted by the pursuing Covenant vessels.

As the Covenant began boarding Pillar of Autumn, the vessel managed to destroy four of the Covenant vessels and force one, Truth and Reconciliation to retreat for repairs. As the boarding of Pillar of Autumn continued, Thom Shephard was forced to release Master Chief Petty Officer John-117 from his Cryo-chamber but was later killed by a conduit explosion.

The Master Chief then proceeded to the bridge of Pillar of Autumn where he was joined with the shipboard AI Cortana, he then evacuated to the recently discovered Installation 04 along with most of Pillar of Autumn's crew. Once on the ground, the ODST battalion made a quick base but separated, with a company heading to the location where the ship's Pelican squadron had landed, Lieutenant McKay's company attacking a nearby butte, and the last two companies manning the base and repulsing an assault by a hundred Ghosts. The ODSTs fended of the attack, killing more than 50 Elites, including a Zealot, but suffered twenty-three killed and sixteen wounded. McKay lost only one marine, while the fourth company lost a few more performing an aerial assault on the butte.

Upon arrival on the ring, Captain Jacob Keyes was captured and the command crew and a squad of marines were executed by the Covenant. The Master Chief managed to rescue 63 naval personnel and Marines before executing a successful rescue operation aboard Truth and Reconciliation, with 36 marines and ODSTs killed and 3 marines plus the Captain rescued.

They also raided a dozen other locations, stealing enemy equipment such as Shades and a large number of Banshees. This would motivate the Covenant to take the humans seriously and place a large amount of effort into stamping out the human forces.

The UNSC forces would also raid the crashed Pillar of Autumn, destroying a large force of Ghosts and a Spirit dropship as well as killing many Covenant troops. They then retrieved many Warthogs and Scorpions from the cruiser's vehicle bays and drove them in a convoy to Alpha Base. At a trio of hills, the Covenant attempted to ambush the convoy with Wraith tanks and air support, but only managed to inflict moderate damage before losing the tanks and a large portion of their ground forces to the Scorpions' return fire. The tanks would later see use around the ringworld, most notably in the defense of Alpha Base.

September 20, 2552
The following day, the crew of Pillar of Autumn launched an attack on the Silent Cartographer island, in their attempt to uncover the purpose of the ring. Fighting their way through the heavily defended Covenant positions, the Master Chief and a handful of Marines, supported by Echo 419 and Bravo 22, discovered the location of Alpha-Halo's Control Room. However, a pair of Covenant Dropships landed and engaged the defenders of the LZ, appearing to kill all the marines that were with the Chief.

Making his way to the Control Room with help from the marines of Fire Team Zulu, Master Chief discovered that the weapons cache that Captain Keyes was looking for was actually a Forerunner base, and that Halo wasn’t a Covenant construct. Master Chief left the Control Room for the swampy areas of the installation. Captain Keyes and Sergeant Johnson had led their two marine squads to the "weapons cache," losing a pair of marines from fire by Covenant defenders. Taking their dogtags and ammo, first squad with Keyes and Johnson continued on while the second squad watched the exit. After a short time, the "weapons cache" Keyes was looking for reveals itself in the form of the Flood. The Flood attacked second squad who barely got a message to Keyes and escaped. However the message was too late as the Flood attacked Keyes' squad, infecting Keyes and Privates Riley, Kappus, Jenkins, Mendoza, and Bisenti, and about 3 others before a pair of marines got out of the room, one of who was killed just outside and the Crazed Marine who escaped. Most of second squad escaped, but three marines were separated and six others were killed. The Chief fought his way into Alpha Halo's main Flood containment facility in his mission to stop the newly released Flood. He then attempted to get the surviving 10 marines of Corporal Lovik's second squad through the swamp to extraction, but was unsuccessful.

Main Article: Battle of Alpha Base

Meanwhile, the Covenant sent the captured Pelican Charlie 217 and its traitorous pilot Lt. Rick Hale to insert 30 Spec Ops Elites commanded by Zuka 'Zamamee to assassinate the (absent) Master Chief and clear a landing for six Spirit Dropships. Although several of the Elites managed to escape into the base, the majority were killed when the ODST forces burned Charlie 217 with jet fuel, killing the Elites that had remained on the platform. The surviving Covenant forces had by this time neutralized the human control rooms, and liberated a large number of Covenant prisoners.

However, the MLA auto-cannons and various other defense systems managed to destroy one of the Spirit dropships and killed many Covenant troops in the others. Groups of Rocket-using marines then added to the casualties. Despite their numerical superiority, the Covenant forces landing on the butte were soon either killed or captured, and the assault on Alpha Base stalled.

The Covenant ground assault, lead by a Zealot Field Master, made significant progress against the humans due to their use of Spirit drophships to clear the way ahead of the ground forces. However, the seeming rout was designed to lure the Covenant into the firing range of a pair of concealed Scorpion main battle tanks, which then tore into the ranks of the aliens and inflicted major casualties.

The Covenant Field Master was killed by the third shot from the tanks, throwing the alien forces into chaos, and of the 150 infantry with him, only a few survived to retreat.

Meanwhile, the Covenant Spec Ops team and the freed Covenant troops ran into a Marine ambush in which all members of both sides were killed other than the Elite Zuka 'Zamamee and the grunt Yayap.But by this time the Covenant ground assault was in full retreat.

The only known Covenant survivors of the aerial assault were Zuka 'Zamamee and the grunt Yayap who then fled the battlefield in a recaptured Banshee.

September 21, 2552
343 Guilty Spark then transported the Master Chief to the Library of Installation 04, where he was tasked with locating the Activation Index. After succeeding, Master Chief prepared to active the ring, but was stopped by Cortana, who, after a brief argument with 343 Guilty Spark, revealed the true function of the ring to John-117; 343 Guilty Spark delightfully confirmed Cortana's belief.

During this time, the humans of Alpha Base planned to counter attack the weakened Covenant. Using the debris from the destroyed Charlie 217 and "wounded marines," a 30 man platoon of ODSTs were able to fool the Covenant into thinking a crash had occurred and that they had a chance to eliminate more humans, sending out a dropship. Once it landed though, the ODST snipers and rocket launchers eliminated their two Hunters and 5 infantry. The dropship returned fire, letting the survivors get into cover. Then the Flood attacked both sides. Calling in reinforcements, the humans were able to win, but lost 15 ODSTs.

Master Chief, deciding not to activate the ring, made an enemy of 343 Guilty Spark and had the Sentinels sent against him. The Master Chief destroyed the three pulse generators that magnify the signal sent out by Halo, disabling the facility for the time being. The Chief was then teleported with Cortana to a Covenant cruiser, where Jacob Keyes was being held. During a second rescue attempt the Chief was too late to rescue Keyes, who had been taken over by the Flood and transformed into a Brain form. The Chief took the neural interface from Keyes, fought his way back through the ship, to the landing bay where he commandeered a Banshee; he then set a course for the Pillar of Autumn, with the intention of destroying the vessel.

September 22, 2552
By this day, only 312 humans (236 marines, 76 naval personnel) remained alive at Alpha Base. To escape, they attacked the Flood-infested Truth and Reconciliation and tried to use it to escape. However, knowing there was Flood still onboard, Lt. McKay destroyed the connection between bridge and engines, crashing the ship into Halo. Although killing the remaining personnel, it stopped the Flood from reaching Earth.

Crashing aboard the Pillar of Autumn, Master Chief made his way to the bridge of the vessel and activate the self-destruct sequences, only to have 343 Guilty Spark cancel the order. Realizing that only a manual self-destruct would work, the Chief made his way to the rear of the ship.

Finally arriving, the Chief destroyed the Pillar of Autumn's fusion reactors which initiates a chain-reaction of explosions. He raced toward the hangar using a Warthog to traverse the spine of the ship. The Chief then commandeers a C709 Longsword-class Inteceptor to escape. The Master Chief and Cortana, onboard the Longsword in the debris field of the destroyed Halo, would, after 2 weeks, find a a cryotube containing Spartan-058 Linda and a Pelican containing Sgt. Major Johnson, Lieutenant Haverson, Warrant Officer Polaski, and ODST Corporal Locklear.

Survivors
It is assumed that only 7 members of the Pillar of Autumn were in space, of which 6 were on a Pelican. , and the other one was on a Longsword fighter. Every other person at the battle presumably died when Halo was destroyed. However, since Sergent Stacker and Chips Dubbo, among others, have been seen again in later games, it can be assumed that there were other survivors.

UNSC

 * UNSC Pillar of Autumn
 * Captain Jacob Keyes
 * SPARTAN-II, Master Chief Petty Officer of the Navy John-117
 * SPARTAN-I, Sergeant Avery Johnson
 * Crew of the UNSC Pillar of Autumn

Covenant

 * Fleet of Particular Justice
 * The Supreme Commander of the Fleet of Particular Justice

Forerunner Constructs

 * 343 Guilty Spark
 * Hundreds of Sentinels

Flood

 * At least one Brain Form
 * Thousands of Combat Forms
 * Hundreds of Thousands of Infection Forms

Related Articles

 * Human-Covenant War
 * Installation 04
 * Raid on the Truth and Reconciliation
 * Battle of the Silent Cartographer
 * Battle of Installation 05