Editing UNSC Marine Corps

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{{Infobox Military Unit
|unit_name=UNSC Marine Corps
|image=[[File:UNSC Marine Corps.PNG|350px]] <!--Stop changing this image-->
|dates= Since [[2163]]
|country= 
|allegiance= [[United Earth Government]]
|branch=[[United Nations Space Command Defense Force|United Nations Space Command]]
|type= 
|role= 
|size=
|command_structure=
|garrison= 
|garrison_label=
|nicknames= "Leathernecks"
|patron=
|motto=
|colors=
|colors_label=
|march=
|mascot=
|anniversaries=
|equipment=
|battles= 
*[[Insurrection]]
**[[Operation: TREBUCHET]]
*[[Human-Covenant War]]
**[[Battle of Harvest]]
**[[Battle of Sigma Octanus IV]]
**[[Battle of Reach]]
**[[Battle of Installation 04]]
**[[Battle of Earth]]
**[[Battle of Installation 05]]
**[[Battle of Installation 00]]
|decorations=
|battle_honours=
|commanders=*[[General (UNSC)|Gen.]] [[Kits]]
*[[Major General|MajGen.]] [[Nicolas Strauss|N. Strauss]]
|notable_commanders=*[[Major (UNSC)|Maj.]] [[Antonio Silva|A. Silva]]
*[[Captain (Marine Corps)|Capt.]] [[Ponder]]
*[[First Lieutenant|1stLt.]] [[Melissa McKay|M. McKay]]
*[[Sergeant Major|SgtMaj.]] [[Avery Johnson|A. Johnson]]
*[[First Sergeant|1stSgt.]] [[Tink Carter]]
*[[Gunnery Sergeant (UNSC)|GySgt.]] [[Edward Buck|E. Buck]]
*[[Gunnery Sergeant (UNSC)|GySgt.]] [[Reynolds]]
*[[Gunnery Sergeant (UNSC)|GySgt.]] [[Pete Stacker (Marine)|P. Stacker]]
*[[Sergeant (UNSC)|Sgt.]] [[John Forge]]
}}
{{Quote|They're the best of the best, but they're only human.|Halo CE Manual}}

The '''United Nations Space Command Marine Corps''' is a branch of the [[United Nations Space Command|UNSC]] [[United Nations Space Command Defense Force|Defense Force]] that is responsible for land-based military operations as well as the protection of [[UNSC Navy|Naval]] vessels and installations from attack.

A rugged and diverse assortment of well equipped and well trained men and women, one of the Marine Corps's most notable conflicts was fighting a losing war against the [[Covenant]]'s highly superior technology and numbers.

==History==
===Before The Human-Covenant War===
The [[UN Marine Corps]] (The predecessors of the UNSC Marine Corps) were one of the primary combat groups fielded by the UN in the [[Interplanetary War]], and were the first military organization [[Argyre Planitia Campaign|deployed offworld]] in 2163. After the [[United Nations]] claimed victory in [[2164]], it reorganized into the [[UNSC]], thereby changing the UN Marine Corps to the UNSC Marine Corps. Later, the UNSC Marine Corps would be responsible for dealing with [[Insurrectionist]] uprisings among UNSC colonies star systems. Also, it is believed that 
some marines were tasked with training individual colonies' militias.

===First Encounters===
The UNSC Marine Corps' first encounter with the [[Covenant]] was at the [[First Battle of Harvest]] in [[2525]]. However, only three marines were present, training the planet's [[Colonial Militia]]. During the battle, [[Captain (Marine Corps)|Captain]] [[Ponder]] became the Corps' first casualty of the war.

The first major encounter between the Marines and the Covenant occurred during the [[Third Battle of Harvest]] in [[2531]]. The Marines quickly established a [[Alpha Base (Harvest)|base of operations]] in Harvest's arctic region. A reconaissance force led by [[Sergeant (UNSC)|Sergeant]] [[John Forge]] was deployed to survey the area. During this patrol, Covenant forces under the command of [[Arbiter (Title)|Arbiter]] [[Ripa 'Moramee]] overran and nearly destroyed Alpha Base. Forge rallied scattered marines, who quickly retook the base from the aliens. After recieving reinforcements and repairing the base, the marines fought through a sizable Covenant garrison force in an attempt to secure a mysterious [[Foreunner]] [[Relic (Structure)|structure]] in the region, so it could be studied by [[Ellen Anders|Professor Ellen Anders]]. Inside the relic, the marines were attacked by numerous Covenant troops; [[Grizzly|Grizzly battle tanks]] were deployed from the orbiting ''[[UNSC Spirit of Fire|Spirit of Fire]]'' to reinforce the assault team. After fighting through the marauding alien forces and escaping the structure, Forge and Anders were evacuated onto the ship.<ref>''[[Halo Wars]]''</ref>

===[[Arcadia]]===
The relic on Harvest pointed to another UNSC colony, Arcadia. Once inside the ship, Anders insisted that what the relic claimed was on Arcadia could be the key to winning the war, and that it must be secured before the [[Covenant]] found it. Reluctantly, [[Captain (Navy)|Captain]] [[James Gregory Cutter|James Cutter]] agreed, and the ''Spirit of Fire'' departed for Arcadia. Two Covenant [[CCS-class Battlecruiser|CCS-class Battlecruisers]] had already arrived, and were sieging the capital city, [[Pirth]]. [[Arcadian Patrol|Local police forces]] and the [[SPARTAN-II Program|Spartan]] [[Red Team]] requested assistance from the ''Spirit of Fire''. The ship deployed a flight of [[AV-14 Attack VTOL|Hornets]] commanded, by Sergeant Forge, to assist the local police, who were trying to protect civilians as they were being evacuated in three [[Human Cargo Ship|large transports]], designated [[Cargo 1]], [[Cargo 2|2]], and 3. [[Cargo 3]] was destroyed early in the evacuation effort after the pilot panicked and took off without overwatch or air support, but the other transports managed to survive, and each lifted off with hundreds of survivors. After that, the Covenant raised a huge energy shield over [[Arcadia Forerunner Ruins|Forerunner ruins]] near an [[Office of Naval Intelligence|ONI]] [[ONI Base (Arcadia)|base]]. Multiple [[M-145D Rhino|M-145D Rhinos]], equipped with plasma weapons, were deployed from the orbiting ''[[UNSC Pillar of Autumn|Pillar of Autumn]]'' to destroy the shield. After a protracted battle, the shield was destroyed, and Marine forces were sent into the ravine, which had previously been obscured by the shield. Forge's forces advanced and saw that the Covenant were trying to build a [[Type-47 Ultra Heavy Assault Platform|Scarab]]. The only working part of the Scarab, the head, was able to wreak havoc, thought the Scarab was eventually destroyed. While Professor Anders was documenting the area for, the Arbiter took her to a Forerunner [[Shield World (Halo Wars)|Shield World]] in order to unlock a [[Forerunner]] fleet.

===Shield World===
The Spirit of Fire followed the Covenant ship to the Flood-controlled [http://halo.wikia.com/wiki/Shield_World_(Halo_Wars) Shield World] . Once there, UNSC forces encountered the Covenant. Eventually, they discovered that the planet was dominated by the [[Flood]] Infection. After a series of skirmishes, they followed Anders' signal and discovered that she was being held inside the shield world, along with a large Covenant presence. The Covenant used Anders to release the fleet, but then Anders escaped and was found by Forge. Anders warned the Spirit of Fire what the Covenant were planning to do, and finally decided to use the Spirit's FTL drive to make the sun inside the planet go supernova, consequently destroying the fleet. When the UNSC forces and the [[Red Team|Spartan Red Team]] were activating it, they were attacked by the Covenant and [[Ripa 'Moramee|the Arbiter]], who was finally killed by Sergeant [[John Forge]]. Unfortunately, the core was damaged, making it necessary to activate the core manually. Forge decided to stay in the core, and then finally the UNSC evacuated all forces. The mission was a success, destroying the entire Forerunner Fleet, Flood infestation and Covenant forces within the planet.

===Battle of Sigma Octanus IV===
There was a Marine presence on the colony world of [[Sigma Octanus IV]]. In the first stage of the battle, during a naval engagement, a [[Covenant Carrier]] was able to land a large contingent of troops on the northern pole of the planet. 

The Covenant were able to take [[Côte d'Azur]], a major population center. Fortunately, almost all of the civilian population was able to be evacuated beforehand, and [[UNSC]] Marine Corps General Kits launched an assault by 0700 hours to retake the city. It was a failure.

Meanwhile, three Marine squads, near Côte d'Azur and under the command of [[Lieutenant]] [[McCasky]] were dispatched for a light reconnaissance of [[Sigma Octanus IV Grid 13 x 24|Grid 13 x 24]]. They were engaged by [[Covenant]] forces, including [[Mgalekgolo|Hunters]], and suffering heavy losses, only one UNSC [[Warthog|M12 Warthog LRV]] of the reconnaissance force survived with four Marines by the names of [[Harland]], [[Walker]], [[Fincher]], and [[Cochran]]. Shortly afterwards, [[Firebase Bravo]] was destroyed by the Covenant, and the [[Warthog]] was forced to divert to [[Alpha Headquarters]]. 

It, too, had been attacked, and while the Covenant attack had been repulsed, heavy casualties were suffered which left Harland the temporary commander of the base. Harland promptly requested reinforcements from the cruiser in orbit, the [[Leviathan]]. The ''Leviathan'' sent a team of twelve [[SPARTAN-II]]s commanded by [[SPARTAN-117]] as reinforcements.<ref>''[[Halo: The Fall of Reach]]'', page 174</ref>.

The surviving Marines of Marine HQ protected a [[Pelican Dropship]] while the SPARTANs detonated a [[HAVOK Nuclear Warhead]] in Côte d'Azur, cleaning the Covenant ground presence on Sigma Octanus IV. They then retreated back to a Pelican dropship, which promptly took off with other Pelicans holding other Marine survivors for the UNSC ''Leviathan''<ref>''[[Halo: The Fall of Reach]]'', page 212</ref>.

===Battle of Reach===
The UNSC Marine Corps maintained a sizable presence of [[Reach]] when the Covenant stormed the planet bypassing the defense fleet in orbit and the [[MAC Gun]] platforms thus make a landing of large numbers of soldiers on the South and North poles. 

By 0555 hours, the Covenant had overrun [[FLEETCOM HQ]] on Reach, destroying the perimeter and swarming the Marine defenders with [[Banshee]]s, [[Type-25 Assault Gun Carriage|Wraiths]], and battalions of infantry. The objective of the Covenant ground armies was to destroy a series of fusion reactors on Reach's surface that powered the orbiting [[Super Magnetic Accelerator Cannon]]-equipped [[Orbital Defense Platform]]s, and thus, disabling the UNSC's major defensive asset and allowing the Covenant fleet to occupy Reach's airspace.

By 0622 hours, the situation was critical enough that the {{UNSCShip|Pillar of Autumn}} sent a full detachment of [[SPARTAN-II]] super soldiers to Reach in a [[Pelican]] drop ship to defend the fusion generators. The [[Orbital Defense Platform]]s were already being vaporized in space, and if they were compromised from the ground, the meager remaining UNSC defense fleet would swiftly fall. 

Meanwhile, [[Charlie Company]], a Marine detachment, was in charge of defending [[Orbital Defense Generator Facility A-331]]. They were forced to defend against a massive Covenant attack, using chain guns on Warthogs, Tanks,and positions from the bunkers, as well as any arsenal available. [[Lieutenant]] [[Buckman]], the CO of Charlie Company, was ordered to flank the Covenant to retrieve the [[NOVA]] bombs, but FLEETCOM, alarmed that the Covenant might overrun ODG A-331, overreacted and carpet-bombed the area, eliminating the Covenant advance as well as most of Charlie Company.

There were four survivors of Charlie Company that held their position until they met with the SPARTANs. The survivors were sent with several heavily wounded SPARTANs to a fall back position at [[Mechanite Mountain]], but all four Marines died from the Covenant, ending the UNSC Marine Corps's known involvement in the Battle of Reach.

===Battle of Installation 04===
====Landfall====
A sizable [[Orbital Drop Shock Trooper]] special forces detachment and a standard [[Marine]] detachment was assigned to the {{UNSCShip|Pillar of Autumn}} for its intended operation to infiltrate [[Covenant]] High Command and kidnap a [[Prophet]]. This prophet was to be used as leverage for negotiating a peace treaty between the [[UNSC]] and the [[Covenant]]. However, the ambush over [[Threshold]] forced the ''[[UNSC Pillar of Autumn|Pillar of Autumn]]'' to crash land on the [[Forerunner]] installation also known as [[Installation 04]] ([[Alpha Halo]]). 
[[Image:Siege.jpg|right|thumb|Marines aboard the ''{{UNSCShip|Pillar of Autumn}}'' take cover from Covenant boarders behind [[Combat Barrier]]s.]]
The ''[[UNSC Pillar of Autumn|Pillar of Autumn]]'''s [[ODST]] detachment consisted of four 130-man companies: Companies A, B, C, and D, for a total of approximately 520 operators. During the Covenant boarding of the ''[[UNSC Pillar of Autumn|Pillar of Autumn]]'', they were assigned to defend the engine room of the warship against the boarding parties. They were extremely efficient in their defense, suffering only several dozen casualties while successfully holding off the Covenant at the two entrances to the massive engine chamber<ref>''[[Halo: The Flood]]'', page 33</ref>. However, the standard Marines did not fare as well in their defense, setting up multiple lines of defense around the periphery of the ''Pillar of Autumn'' and utilizing [[Combat Barrier]]s and urban combat techniques in the restrictive environment to hold off the enemy, which were [[Elite]]s and [[Grunt]]s. Ultimately, they were unsuccessful, and the Covenant managed to infiltrate many compartments of the warship before [[Captain (Navy)|Captain]] [[Jacob Keyes]], commander of the ''Pillar of Autumn'', decided it was a lost cause to hold off superior numbers of attacking Covenant warships as well as internal boarders and ordered all hands to evacuate.<ref>''[[Halo: Combat Evolved]]'', ''[[Pillar of Autumn (Level)]]''</ref>.

Naval crewmen, standard Marines, and [[SPARTAN-117]] evacuated in the ship's [[Bumblebee]] life pods while the ODST companies utilized [[Human Entry Vehicle]]s. The landings, however, had numerous problems and killed dozens of UNSC Marines and Sailors alike. Major Antonio Silva, the ODST Commander, ordered all surviving ODST units to secure a lightly-defended Covenant-held butte, which he turned into a coordinating home base for the UNSC resistance to come against the Covenant. After securing it, the ODSTs worked to make it a strategically defensible point for the UNSC survivors. It was christened [[Alpha Base]] by Major Silva, who also ordered that all remaining UNSC forces to rendezvous there to make a stand. The Covenant launched a large vehicular [[Battle of Alpha Base|raid]] on Alpha Base of nearly a hundred [[Ghost]]s, but the 200 or so available ODSTs were able to repulse the poorly led assault.

The Covenant placed as high a priority on recovering [[UNSC]] life pods as the UNSC forces did. Many of the successful landings were soon attacked by Covenant forces in an effort to minimize the number of Marines on the ring world. Individuals and teams such as [[SPARTAN-117]] and the [[Pelican]] ''[[Echo 419]]'' spent a considerable amount of time securing life pods throughout the installation, and regrouping the Marines to later lead the human resistance. [[Cortana]] was monitoring the Covenant Battlenet and discovered that [[Captain]] [[Jacob Keyes]] had made a safe landing off the ''[[UNSC Pillar of Autumn|Pillar of Autumn]]'' and had been captured by the [[Covenant]] ground forces. She also found that he was being held on the Covenant ship ''[[Truth and Reconciliation]]''.

====''Truth and Reconciliation''====
[[Image:Halo-09.jpg|thumb|right|[[Fire Team Charlie]] secures the [[Gravity Lift]] of the ''[[Truth and Reconciliation]]'' while awaiting ''[[Echo 419]]'' to bring in further reinforcements.]]
[[SPARTAN-117]] led [[Fire Team Charlie]] to rescue Keyes from the grounded Covenant {{Class|CCS|Battlecruiser|}}''[[Truth and Reconciliation]]''. They would set down a short distance from the Covenant battle cruiser, and then infiltrate through its [[Gravity Lift]]. From there, they would find Keyes, rescue him, and then evacuate.

Surprisingly, the plan went quite well. Despite a rather large Covenant force guarding the way into the ''[[Truth and Reconciliation]]'' and a pair of [[Hunters]] being deployed at the Gravity Lift (among other things), the approach was simple. From there, they were able to go up the Gravity Lift into the belly of the ''[[Truth and Reconciliation]]''. It was at this point that the Marines were ambushed by an Energy Sword wielding Elite. The Chief killed it, but unsure of what the device was at that time was unable to implement it against the Covenant. This was the UNSC's first encounter with new Covenant technology. It is worth noting that there were a few Type-25 Assault Gun Carriage or Wraiths in the hangers at that point also. The UNSC forces fiercely battled their way through alien corridors for fifteen minutes before reaching a spacious hangar bay. However, before they could continue, the Covenant were able to lock the doors on the Marines and [[John-117]], number of Marines, [[Cortana]] was able to use her computer countermeasures to force open a door that lead from the hangar to the bridge of the warship. Master Chief ordered his Marine comrades to wait in the bridge while he assaulted a Covenant brig, freeing Keyes and also three other captured Marines. However, by the time they returned to the bridge, [[Energy Sword]]-wielding [[Elites]] had slain the rest of the rescue team. They headed to the Hanger Bay for evacuation, but Covenant air patrols prevented their rescue. Instead, the team chose to hijack an enemy [[Spirit]] dropship that was laying dormant in the hangar bay, with Captain Keyes freed and secured<ref>''[[Halo: Combat Evolved]]'', ''[[The Truth and Reconciliation (Level)]]''</ref>.

Shortly afterward, the UNSC Marine forces stationed at Alpha Base, under the command of Major Silva, decide to embark on a risky raid on the crashed hulk of the ''[[UNSC Pillar of Autumn|Pillar of Autumn]]'' to get much-needed supplies and ammunition, vehicular support, and fuel for the ferrying [[Pelican]] Drop ships. A small 62-man ODST force under the leadership of Lieutenant McKay raided the Covenant-patrolled crash site of the ''Pillar of Autumn'', using sniper fire to eliminate most of the defending [[Ghost]] attack vehicles and infantry, and then securing the ship with 10 casualties, securing much-needed supplies for the UNSC forces.<ref>''[[Halo: The Flood]]'', page 136</ref> However, the Covenant learned about this, and before McKay's force can return to Alpha Base and drop off the newly-seized supplies and vehicles that they had secured from the wreck of the ''Pillar of Autumn'', they were intercepted by a superior Covenant force in the rocky terrain. The tide of battle is turned to the UNSC's favor, however, by discipline, organization, and luck. The UNSC's four [[Scorpion Tank]]s used shell bombardment to destroy the attacking Covenant [[Type-25 Assault Gun Carriage|Wraiths]], while the UNSC Warthogs fought off waves of assailing [[Banshee]] attack craft and [[Ghost]]s. The Covenant's aggressive tactics yielded no advantage, and the well-coordinated UNSC rocket units and a particularly bold feint by Second Lieutenant [[Oros]] destroyed the dozens of Covenant Banshees, and Marine sharpshooter [[Lance Corporal]] [[Jones]] took a serendipitous sniper rifle shot, killing a Covenant [[Elite]] [[Ado 'Mortumee|officer]], disorienting and fragmenting the Covenant resistance as UNSC forces plowed through the Covenant remnants.<ref>''[[Halo: The Flood]]'', page 160</ref>.

====The Flood====
{{Quote|Ahh... augh! Get [[Flood Infection Form|it]] off! Get it-augh!|[[Private]] [[Riley]], first Known UNSC casualty to the [[Flood]] on [[Installation 04]]}}

Meanwhile, a [[Covenant]] [[Elite]], [['Qualomee]], surrendered to the UNSC and yielded intelligence about a Covenant arms cache in a faraway swamp. After Captain Keyes meets Major Silva and congratulates him and his [[ODST]]s for establishing Alpha Base for the UNSC, Keyes decides to lead a platoon of Marines under the leadership of [[Staff Sergeant]] [[Avery J. Johnson]] to secure this Covenant arms cache while [[Master Chief]] is ordered to a remote island where a [[Forerunner]] construct named the "[[Silent Cartographer]]" is stationed - a construct that is believed to hold an entire and fully-detailed map of Installation 04. Securing the intelligence would give the UNSC an inestimable edge in their resistance efforts.
[[Image:Kappus_tap.JPG|right|thumb|UNSC Marine [[Kappus]] opens a locked door in the Covenant "weapons cache", unknowingly unlocking the [[Flood]].]]
Two Pelican Drop ships inserted two squads of Marines (lead by [[Gunnery Sergeant Waller]] and [[Sergeant]] [[Stacker]]) and [[Master Chief]] to an edge of the island. They were deployed under fire, but managed to secure a beachhead and a landing zone for the UNSC to land further reinforcements (including an [[M12 Warthog LRV]]). SPARTAN-117 and two Marines, PFC [[Hosky]] and an unnamed Female Marine [[corporal]], took the Warthog, driving it to a cliff that was the entrance to the facility that housed the Silent Cartographer. However, the Covenant knew that the UNSC was attempting to secure the intelligence, and locked the entrance way, forcing the trio to make a detour to a security substation, deactivating the locked door before finally being able to tunnel their way through the Covenant defenses stationed inside the subterranean facility and retrieving the intelligence.

The surviving Marines still waiting on the landing zone were scheduled to be reinforced by Pelican [[Bravo 22]] when it was shot down by ground arsenal. Shortly afterward, a pair of [[Spirit]] drop ships converged on the Marines by the landing zone, overwhelming them on the exposed terrain of the beachhead while SPARTAN-117 was still within the bowels of the underground facility. The forces on the beachhead are presumed dead. The lack of a UNSC-held landing zone on the surface of the island meant that ''Echo 419'' could not extract [[Master Chief]] and his vital intelligence. However, [[Cortana]] found that there was a massively honeycombed system of massive open corridors that permeate the ground of Installation 04, allowing a vehicle that entered the system to travel essentially anywhere undetected. ''[[Echo 419]]'' was able to slip into the system and rescue [[Master Chief]]. Using this system, [[Master Chief]] was able to be transported to the installation's Control Room<ref>''[[Halo: Combat Evolved]]'', ''[[The Silent Cartographer (Level)]]''</ref>.

[[Image:343GS-Marine Run.jpg|thumb|right|Captain Keyes's second squad flees from the Flood-infested arms cache after meeting with [[Master Chief]].]]Captain Keyes's team, meanwhile, landed near the site of the supposed "weapons cache". The two Marine teams cleared the Covenant defenses and began to search the underground facility where the arms were supposedly stored. One team stayed back while the other team, led by [[Staff Sergeant]] [[Johnson]], searched the facility. Eventually, they ran across a door that had been electronically locked by the Covenant. Despite the protest of the technician, [[Captain Keyes]] ordered the door to be unlocked to gain access. Shortly after entering the room, however, the advance team, including Captain Keyes, was attacked by parasitic organisms called [[Flood]]. [[Staff Sergeant]] [[Johnson]] managed to escape after the Flood [[Infection Forms]] took over his fellow Marines, that infection did not incur due to his deteriorated nervous system, courtesy of [[Boren's Syndrome]]. [[Private]] [[Bisenti]] would also survive the attack but is speculated to have died when [[Spartan 117]] blew up [[Installation 04]]. Due to a failed infection attempt, [[Private First Class]] [[Jenkins]] was infected but had control over his consciousness and some body functions. [[Jenkins]] was later captured and interrogated by UNSC forces.

[[Cortana]] had already learned of the threat the Flood was and sent [[SPARTAN-117]] to save Keyes. However, the Spartan would only find Jenkins' helmet and it's mission log. When he was on the way to the evacuation site, he fought against Flood Infection and Combat Forms of both Covenant Elite and human Marine form, then ran into a surviving squad of Marines and began retreating with them to a nearby structure, whilst being assaulted by Flood Combat forms. After securing an LZ for dropship ''Echo 419'', he would then disappear after encountering [[343 Guilty Spark (Monitor)|343 Guilty Spark]].<ref>''[[Halo: Combat Evolved]]'', ''[[343 Guilty Spark (Level)]]''</ref>. 

Meanwhile, Alpha Base came under heavy attack from a Covenant force. The Covenant had identified that SPARTAN-117 was responsible for the majority of the hundreds of casualties during the raid on the ''[[Truth and Reconciliation]]'', and an ambitious [[Special Operations Elite]] named [[Zuka 'Zamamee]] was tasked with leading a platoon of Special Operations Elites into the bowel of Alpha Base to assassinate the [[SPARTAN-II|Demon]] while a much larger Covenant force distracted the UNSC defenders. Using a captured Pelican drop ship, [[Charlie 217]], 'Zamamee infiltrated the UNSC HQ, but SPARTAN-117 was nowhere to be found. Meanwhile, [[Spirit]] drop ships hit the UNSC defenses, but are thrown back by massive amounts of sniper rifle fire and several [[Scorpion Tank]]s. Furthermore, the ODSTs organize several hunter-killer teams to re-secure the HQ, murdering all the Special Operations Elites save 'Zamamee, who was able to rescue a captive Grunt named [[Yayap]] and escape with Yayap in a [[Banshee]] fighter<ref>''[[Halo: The Flood]]'', page 220</ref>.

====Containment====
While [[SPARTAN-117]] journeyed through various areas in [[Installation 04]], [[Cortana]] was able to briefly contact [[Alpha Base]], informing them that [[SPARTAN-117]] will use the ''[[UNSC Pillar of Autumn|Pillar of Autumn]]'''s reactors to trigger a thermonuclear explosion that would destroy [[Installation 04]]. However, the explosion would kill all life on the ring world if the UNSC forces failed to escape before the detonation. Major Silva came up with a daring plan: to recapture the damaged ''[[Truth and Reconciliation]]'', already taken to launch readiness by a [[Covenant]] repair team, and to use it to escape the ring while [[SPARTAN-117]] sets off the delayed thermonuclear reaction and escapes as well. Afterward, [[SPARTAN-117]] will rendezvous with the UNSC-controlled ''Truth and Reconciliation'' and then they will return to [[Earth]], heralding a glorious victory for the UNSC: a superweapon destroyed, a [[Covenant]] armada annihilated, and the first [[Covenant]] warship ever captured. 

However, this plan was not perfect. [[Alpha Base]]'s contingent learned of the [[Flood]] as a brief skirmish with nearby [[Covenant]] patrols led to an exaggerated battle as the [[Flood]] attacked, and the [[UNSC]] personnel were mostly horrified by the [[Flood]]'s combat potential and viciousness.<ref>''[[Halo: The Flood]]'', page 251</ref> After it was learned that Flood were aboard the ''Truth and Reconciliation'', ODST Lieutenant McKay and UNSC AI [[Wellsley]] were convinced that the UNSC survivors should not risk severe casualties boarding a [[Flood]]-infested [[starship]]... and even if they prevail and brought the [[warship]] to [[Earth]], if any [[Flood]] managed to invade [[Earth]], the planet would fall<ref>''[[Halo: The Flood]]'', page 317</ref><ref>''[[Halo: The Flood]]'', page 331</ref>. However, Silva, the commanding officer of all of [[Alpha Base]]'s forces after [[Keyes]]'s tragic death, demurred, and instead assaulted the ''Truth and Reconciliation'', with his [[ODST]] special forces operators securing the ship with minimal casualties and the non-combat personnel in tow. Surviving senior naval officers from the ''Pillar of Autumn'' were sent in after the [[ODST]]s deem the warship as "secure", and they moved swiftly to under see last-minute repairs to the ''Truth and Reconciliation'' before it took off.

However, McKay still held doubt - even if the ''Truth and Reconciliation'' took off successfully and reached [[Earth]] without incidence, the epidemiological threat of the [[Flood]] meant that if even one parasite managed to infect a [[human]] on [[Earth]], it would be a disaster of a galactic scale. McKay, in conscience, made the decision to damage the ''Truth and Reconciliation'''s reactors and destroy the warship, killing herself and all 312 [[UNSC]] personnel and surviving [[Flood]] beings on board<ref>''[[Halo: The Flood]]'', page 332</ref>, thereby destroying nearly all of the [[UNSC]] presence on the ring.

====Escape====
While almost all of [[Alpha Base]]'s personnel were eliminated in the tragic self-detonation, [[Avery J. Johnson]] did not make it onto the ''[[Truth and Reconciliation]]'' after surviving the [[Flood]] attack. He was able to join three other UNSC personnel that were, likewise, not aboard the ''Truth and Reconciliation'': [[Office of Naval Intelligence]] [[Lieutenant]] [[Elias Haverson]], ODST [[Corporal]] [[Locklear]], and [[Warrant Officer]] [[Sheila Polaski]]. Together, the four escaped [[Installation 04]] in a [[Pelican Dropship]]<ref>''[[Halo: First Strike]]'', page 48</ref> before [[SPARTAN-117]] set off the thermonuclear detonation, himself escaping in a [[C709 Longsword-class Starfighter|C709 ''Longsword''-class Starfighter]]<ref>''[[Halo: Combat Evolved]]'', ''[[The Maw (Level)]]''</ref>.

After [[Installation 04]]'s destruction, [[Cortana]] conducted a scan of the interstellar debris of [[Installation 04]], and found an echo of [[Polaski]]'s [[dropship]]. [[SPARTAN-117]] was able to link up with the four other [[UNSC]] survivors of the cataclysm, but seven [[Covenant]] warships: six [[Covenant Cruiser]]s and one 3-kilometer [[Covenant Flagship]], entered the system and opened fire at the fighter and the [[Pelican]]. [[SPARTAN-117]] ordered everyone into the [[Longsword]] while the [[Pelican]] was sent ahead as bait, drawing [[plasma]] fire from the [[Covenant]] starships while [[Cortana]] remotely hacked into the [[Covenant]] task force's [[Battlenet]], causing electronic mayhem that temporarily stunned the weapons aboard the warships while the [[Longsword]], with [[SPARTAN-117]], [[Johnson]], [[Locklear]], [[Polaski]], and [[Haverson]] on board, slipped into the hangar of the [[Covenant]] [[Flagship]]<ref>''[[Halo: First Strike]]'', page 58</ref>.
[[Image:Marine.png|thumb|right|[[Corporal]] [[Locklear]] fights the [[Covenant]] with an [[MA5B Assault Rifle]] in the brief battle inside the ''[[Ascendant Justice]]''.]]
The small group of unprepared [[UNSC]] warriors fought through [[Elite]] defenders while [[Cortana]] slipped into the [[Covenant]] [[Flagship]]'s computer systems from a fiber optic port, and proceeded to drain atmosphere from most segments of the ship, asphyxiating most of the [[Covenant]] guards. However, the bridge's crew still remained alive, and sealed the doors to the bridge, barricading themselves from the [[UNSC]] attackers. This measure was ultimately futile: [[SPARTAN-117]] used a [[plasma grenade]] to electromagnetically scramble the locks to the doors, and the [[UNSC]] forces seized the understaffed bridge with minor difficulties. [[SPARTAN-117]]'s personal energy [[shield]] failed just as an [[Energy Sword]]-wielding [[Zealot]] appeared. [[SPARTAN-117]] nearly had his arm amputated in the resulting wrestle, but Marines [[Johnson]] and [[Locklear]] were able to severely wound the [[Zealot]], before throwing him into an escape pod and launching it<ref>''[[Halo: First Strike]]'', page 74</ref>.

[[Cortana]] interfaced with the bridge's navigational controls to let the now [[UNSC]]-controlled [[flagship]], ''[[Ascendant Justice]]'', flee from the system, but a [[Covenant]] AI countered her, physically disabling the [[Slipspace]] drive of the ''[[Ascendant Justice]]'' and preventing [[Cortana]] from executing a jump out of the system before the six other Covenant Cruisers vaporize the flagship. [[SPARTAN-117]], however, made a journey through the damaged warship to kill the [[Grunt]]s guarding the disabled [[Shaw-Fujikawa Translight Engine|Slipspace drive]], and then forces a [[Covenant]] [[Engineer]] to repair the drive, allowing [[Cortana]] to program the ''[[Ascendant Justice]]'' to jump from the system, just barely surviving the bombardment of the six [[Covenant]] [[Cruiser]]s, thus ending the [[UNSC]] retreat from the war-torn system.<ref>''[[Halo: First Strike]]'', page 87</ref>

===Battle of Earth===
[[Image:DSC00124.JPG|right|thumb|[["A" Company]] of the [[405th Marine Infantry Division|405<sup>th</sup> Marine Division]] before attacking the [[Scarab]] walker.]]
[[File:Marinevswraith.jpg|thumb|A Marine armed with only a [[M6C/SOCOM|Magnum]] faces a [[Covenant]] [[lance]] and a [[Wraith]].]]
{{Main|Battle of Earth}}

{{Quote|[[UNSC In Amber Clad|We're]] taking this fight to the surface.|[[Commander (UNSC)|Commander]] [[Miranda Keyes]]}}

The [[UNSC]] Marine Corps remained in force on [[Earth]] and its geosynchronous [[Orbital Defense Platform]]s, and were thus mostly prepared to repulse a relatively small [[Covenant]] invasion when fifteen [[Covenant]] capital warships, two [[Assault Carrier]]s and thirteen [[Covenant Cruiser]]s, entered the Sol System.

Because the large number of orbital [[Magnetic Accelerator Cannons]] made it almost impossible for any of the [[Covenant]] warships to reach [[Earth]] unscathed, the [[Covenant]] sent [[Covenant Boarding Craft|boarding craft]] to board numerous [[Orbital Defense Platforms]]. The boarders swiftly penetrated the platform's infantry defenders and set bombs in the core of the stations and then detonated them, destroying the defense station inside-out with minimal losses. ''[[Malta Station]]'' and ''[[Athens Station]]'' fell almost immediately to the internal sabotaging.

[[Covenant]] forces invaded ''[[Cairo Station]]'' as well, the command center for [[UNSC]] fleet operations during the battle. The crew of the ''[[Cairo]]'' held out longer, albeit with heavy casualties, and [[Marines]] and crewmen fought a coordinated holding action, trying to force the boarders out of the peripheral hangars and the intermediate common rooms, but their defenses were penetrated by a small force of [[Elite]]s and [[Grunt]]s that planted a bomb in the Fire Control Center of ''[[Cairo Station]]''. Only [[SPARTAN-117]]'s timely reinforcement of the [[Marine]] garrison and his assault on the Fire Control Center managed to '''disarm''' the bomb in time, thus saving ''[[Cairo Station]]'' from destruction.<ref>''[[Halo 2]]'', ''[[Cairo Station (Level)]]''</ref>. John then proceeded to send the bomb to another Covenant ship, utterly destroying it.

However, despite the fact that ''[[Cairo Station]]'' and hundreds of others of [[Orbital Defense Platforms]] still stood, the loss of the ''[[Malta]]'' and ''[[Athens]]'' allowed a [[Covenant]] [[Assault Carrier]] to penetrate the [[UNSC]] Navy's defensive web around [[Earth]], and this [[Assault Carrier]] attacked [[New Mombasa]], [[Africa]]. 

However, the [[405th Marine Infantry Division|405<sup>th</sup> Marine Infantry Division]], some of whose elements were stationed in [[Mombasa]], [[Kenya]] at the time, were able to battle against the [[Covenant]] as the [[Assault Carrier]] landed [[Phantom]]s, [[Orbital Insertion Pod]]s, and used its [[Gravity Lift]] to directly deploy reinforcements. Furthermore, [[UNSC In Amber Clad|In Amber Clad]] was also able to use its [[Pelican]]s to deploy [[Marines]], vehicles, and equipment to assist the 405<sup>th</sup> Marine Division. 

''[[UNSC In Amber Clad|In Amber Clad]]'' sent three [[Pelican Dropships]] to reinforce and to drop off [[Marine]] and [[ODST]] fire teams at [[Grid Kilo 23]], where [[SPARTAN-117]] and [[Johnson]] would lead a coordinated [[Marine]] assault to liberate the [[Covenant]]-contested city center, when the [[Pelicans]] were unexpectedly attacked by a [[Scarab]] en route to their landing zone. Two of the [[Pelicans]] were forced to break off when one of the ''[[UNSC In Amber Clad|In Amber Clad]]'''s [[Pelicans]], which contained [[SPARTAN-117]] and [[Sergeant Johnson]], crashed into a building. 

Miraculously, everyone aboard the Pelican except the pilot survived, and [[SPARTAN-117]] was able to rally the Marine passengers, holding a nearby battle-damaged building against multiple Covenant attacks until the Marines could be evacuated at a nearby clearing. 

Meanwhile, SPARTAN-117 proceeded to relieve a small ODST force, under the command of [[Gunnery Sergeant]] [[Pete Stacker]], at [[Hotel Zanzibar]], and then fought through a Covenant-controlled tunneled highway where the [[Covenant]] were using the tunnel as a supply route.<ref>[[Outskirts(level)]]</ref>. 

However, the Scarab brushed aside Marine defenses, walking over the highway, and then past a large bridge and into the midsection's of the city completely unopposed by Marine small arms fire<ref>''[[Halo 2]]'', ''[[Outskirts (Level)]]''</ref>.

[[Image:Scarabcannon.jpg|right|thumb|The [[Scarab]] destroys a [[UNSC Marine Corps]] [[Scorpion Tank]] in a single shot.]]
[[SPARTAN-117]] and a small team of Marines pursued the lumbering walker, fighting through long segments of Covenant-controlled city locations until reaching the city center, where [["A" Company]] of the [[77th Marine Regiment|77<sup>th</sup> Marine Regiment]] defended against waves of Covenant [[Ghost]]s, [[Type-25 Assault Gun Carriage|Wraiths]], and [[Phantom]]s in a fortified industrial building. 

Completely undeterred by UNSC Marine Corps [[Scorpion Tank]]s or machine guns, the Scarab too brushed aside "A" Company in its fortified building, until it was caught in a nearby canal system and physically trapped. Pelicans commenced air strikes on the trapped walker, but the armor was barely scarred, and there was no other choice but to board the Scarab itself and destroy internally. While "A" Company's remnants provided suppressive fire, [[SPARTAN-117]] boarded the enemy walker when the Scarab was stuck by a bridge, killing its crew (numerous Grunts and Elites) and destroying it<ref>''[[Halo 2]]'', ''[[Metropolis (Level)]]''</ref>.

===Battle of Installation 05===
{{Main|Battle of Installation 05}}

{{Quote|[[Cortana]]? What exactly am I looking at?|[[Commander Miranda Keyes]]}}
{{Quote|[[Installation 05|That]]...is another [[The Halos|Halo]].|[[Cortana]]}}
{{Quote|Say what?!|Sergeant Major [[Avery Johnson|Avery J. Johnson]]}}
[[Image:Hevstohalo05.jpg|right|thumb|[[Human Entry Vehicle]]s from the {{UNSCShip|In Amber Clad}} insert into the atmosphere of [[Installation 05]].]]

After the [[Slipspace]] cataclysm over [[Mombasa]] involving the [[Prophet of Regret]]'s [[Assault Carrier]], [[UNSC In Amber Clad|''In Amber Clad'']] pursued the Prophet of Regret's carrier through [[Slipspace]] to [[Installation 05]] (Delta Halo), where Regret was determined to sermonize and then activate the ring world and bring about [[The Great Journey]] to all of the [[Covenant]] and lead them to a believed transcendence. 

While the carrier sent [[Phantom]] drop ships to the surface to land the [[Covenant Army]] in the immediate area and to allow Regret to begin his religious ceremony in a Forerunner temple before activating the ring, the ''In Amber Clad'' passed over the approximate position where Regret's temple was, deploying ten [[Human Entry Vehicle]]s, and shortly afterward, a flight of Pelican Dropships.

While only a handful of HEV pods survived the insertion, the surviving ones contained [[SPARTAN-117]] and several heavily armed [[Orbital Drop Shock Trooper]]s. Together, they cleared a small area of [[Shielded Plasma Cannon]]s and a small group of Covenant soldiers, establishing an LZ for a Pelican Drop ship to deploy an [[M12 Warthog LRV]] and another pair of ODST operators. 

SPARTAN-117 took the Warthog, and with the help of the ODSTs, fought through a Covenant-controlled bridge before another Pelican deployed a M808B Scorpion MBT that provided extra firepower for a UNSC offensive to push through two large Forerunner temple ruins, and to neutralize the Wraith where yet a third Pelican from the ''In Amber Clad'' dropped off resupply drop pods and Marine reinforcements. 

After battling through a ravine entrenched by aerial [[Yanme'e|Drones]] and [[Jackal Sniper]]s, the UNSC force reached a small Forerunner temple, where SPARTAN-117 and two remaining Marines fought off a pair of [[Honor Guard Elite]]s<ref>''[[Halo 2]]'', ''[[Delta Halo (Level)]]''</ref> before continuing onwards through a series of closed temples before reaching an open circular platform where a fourth Pelican was scheduled to air-drop additional armaments. 

However, before that could happen, SPARTAN-117 and whatever surviving Marines were attacked by an airborne [[Phantom]] dropship that deployed two heavy [[Hunter]] warriors that savagely assailed the UNSC personnel before they were fought off and the fourth Pelican arrived to bring [[BR55 Battle Rifle]]s, Sniper Rifles, and [[M19 SSM Rocket Launcher]]s. SPARTAN-117 continued to take a gondola from the open platform, fighting off enemy [[Banshee]] fighters and [[Ranger Elite]]s to reach a series of submerged temple structures and finally another gondola to the temple where Regret was sermonizing.

SPARTAN-117 and his Marines began fighting off [[Energy Sword]]-armed [[Honor Guard Elite]]s, managed to assassinate the Prophet of Regret before the [[Prophet of Truth]] and [[Prophet of Mercy]] ordered an Assault Carrier to use an [[Energy Projector]] to vaporize the temple in a vain attempt to kill the "Demon", afterward which contact was lost with SPARTAN-117 and whatever remaining Marines that were accompanying him at the time.

Meanwhile, at ''[[High Charity]]'', the [[Changing of the Guard]] occurred, and the [[Arbiter (Character)|Arbiter]] was deployed to the [[Sentinel Wall]]<ref>''[[The Official Halo 2 Strategy Guide]]'', page 118</ref> to deactivate the containment shield that prevented any being from journeying to the [[Library]] and retrieving the [[Index]]. After the Containment Shield was deactivated, apparently a company-sized Marine unit was sent to the Flood-Infested Wall<ref>''[[The Official Halo 2 Strategy Guide]]'', page 115</ref><ref>''[[Halo 2]]'', ''[[Sacred Icon (Level)]]''</ref> to try to make their way to the Library, but were overwhelmed by the Flood and assimilated. 

However, while the Arbiter punched through heavy Flood defenses surrounding the Library, the UNSC tried again to attack the [[Library]] and secure the [[Index]] to ensure that the Covenant would not use it to activate Installation 05 and cleanse the galaxy of sentient life in their misguided religious quest. While the Arbiter cleaned out the Flood infestation barring way to the Library, the UNSC were able to slip a small force of Marines directly next to the Forerunner structure, who managed to infiltrate it, but took casualties from [[Flood infection form]]s. 

At the end, only [[Miranda Keyes]] and [[Avery Johnson]] survived, but while Commander Keyes secured the Index, the Arbiter managed to race into the Library, incapacitating Perez and MacKenzie before launching a sneak attack on Johnson and Keyes, knocking them both unconscious before securing the Index for the Covenant<ref>''[[Halo 2]]'', ''[[Quarantine Zone (Level)|Quarantine Zone]]''</ref>.

===[[Battle of High Charity]]===
{{Main|Battle of High Charity}}

However, [[Spartan-117]] had survived the Covenant vaporization of Regret's Temple, but had a more insidious fate: deceived by the Flood overlord creature known as the [[Gravemind]], he became the Flood's pawn, being teleported to ''[[High Charity]]'' in an attempt to battle through legions of Covenant troops to capture or kill the [[Prophet of Truth]] and secure the Index to ensure that Truth would not activate Halo. 

Early on during the Battle of ''High Charity'', however, [[Cortana]] detected the [[CNI]] wave signatures of several UNSC Marines inside the bowels of ''High Charity''. SPARTAN-117 took a short detour, launching an attack on a four-story Covenant detention facility and rescuing five Marine prisoners from a pair of heavily guarded Covenant detention blocks, who aided him in his battles through ''High Charity''. 

In the end, however, none of the Marines survived (even if you some how complete the level with some of them still alive, they won't be there in the next Master Chief level), and the [[Prophet of Truth]] escaped from SPARTAN-117's grasp, fleeing in a Phantom drop ship while [[Tartarus]], Chieftain of the Brutes, took the imprisoned Keyes and Johnson, along with a cohort of [[Honor Guard Brute]]s, in two separate [[Phantom]]s to Installation 05, where Tartarus planned to use the Index to activate Halo at the Control Room of Installation 05<ref>''[[Halo 2]]'', ''[[Gravemind (Level)]]''</ref>.

Meanwhile, the ''In Amber Clad'' had not fared well after Keyes's team's departure from the frigate. Flood forces managed to storm aboard by use of crashed [[Pelicans]], killing the human crew and using their unprecedented sentience to crew the ship. They managed to crash it onto a high tower on ''High Charity'', spreading Flood into the Covenant planetoids. Pelican dropships provided the Flood with extensive routes to invade ''High Charity''. 

A number of its crew were assimilated into the insular of the parasite, fighting against SPARTAN-117 as the Master Chief battled through a Flood-infested ''High Charity'' to secure access to the [[Forerunner Ship]]<ref>''[[Halo 2]]'', ''[[High Charity (Level)]]''</ref>.

While Tartarus took the Index and Miranda Keyes in one Phantom to the Control Room, the other Phantom, carrying Johnson, diverted its route. When arrived with two other captured Marines, the Arbiter arrived and with the distraction, the Marines and himself managed to slip through to an inactive [[Scarab]] walker while two nearby Marines, most likely [[Sergeant Stacker]] and [[Sergeant Banks]], fought off a large pack of [[Brute Captain]]s with [[Plasma Pistol]]s. These two Marines were saved when the Arbiter arrived, slaying the Brutes. 

However, Johnson pointed the Scarab's main cannon at the Arbiter...but not in bad will. The Arbiter and Johnson made a truce. Johnson would use the main cannon of the Scarab to punch a hole in the surface of the Control Room while the Arbiter would charge in with a [[Banshee]] and defeat Brute Captains and Brute Honor Guards before confronting [[Tartarus]] while Johnson would dismount from the Scarab, joining a large number of [[Covenant Separatist]] [[Councilors]], [[Zealots]], and [[Special Operation Elite]]s in aiding the Arbiter to kill Tartarus and prevent him from using the Index to activate Halo.

However, Tartarus put up a significant resistance, and despite being heavily outnumbered by the Arbiter's Elite comrades, used his personal energy shield and the gargantuan [[Fist of Rukt]] to defend himself. In the end, however, Tartarus was unsuccessful. 

Johnson used his exceptional marksmanship to take down Tartarus's powerful shields from afar with a [[Particle Beam Rifle]] while the Arbiter and his allies attacked the unshielded Tartarus, finally killing him and bringing an end to the Chieftain of the Brutes and preventing the firing of the Halos, terminating the UNSC Marine Corps's involvement at Installation 05.

===Late Battle of Earth===
[[Image:Halo 3 Marines.png|right|thumb|Four Marines take cover in the jungles around [[Voi]].]]

When the Arbiter arrived on Earth with [[Commander Miranda Keyes]] and Sergeant Major Avery J. Johnson, he requested a truce between the Sangheili and Human races. Knowing the desperate situation for the human race being close to extinction from the remainder of the Covenant, the Arbiter united the Separatists and the Human Race.

The UNSC Marine Corps had a substantial involvement in the defense of Earth during the Battle of Earth, being the majority of the UNSC's ground defenses when the Covenant landed on Earth in multiple locations, which included the continent of [[Africa]].

A scattered Marine presence appeared to remain in force in the immediate vicinity of [[New Mombasa]], where a [[Slipspace]] disaster wiped off a significant number of Marine assets, including a portion of the [[405th Marine Infantry Division|405<sup>th</sup> Marine Infantry Division]]. 

[[Marine]] forces managed to hold out in an underground base, waging a guerrilla war against the [[Covenant]] occupiers of East Africa for some time before the [[Master Chief]]'s arrival from on board the [[Forerunner Dreadnought]] <ref>Sierra 117 (level)</ref>. After his recovery, Marine forces prepared to launch an offensive against the Covenant and reach what they thought to be the [[Installation 00|Ark]]. Unfortunately, the Covenant found them first, and assaulted the base with heavy numbers of infantry. The Marines, Master Chief, and the Arbiter managed to fend them off long enough to evacuate the remainder of the survivors, and destroyed the base rather than let the Covenant learn of their plan<ref>Crows Nest (level)</ref> - the Master Chief personally led a small number of Marines along the Tsavo Highway, penetrating through numerous blockades and passing patrols of [[Type-25 Rapid Assault Vehicle|Choppers]] and [[Wraiths]], eventually reaching the town of Voi<ref>Tsavo Highway (level)</ref>.
[[Image:58478962-Full.jpg|thumb|Marines supported by [[Voi Factory Workers|Factory Workers]] during the [[Battle of Voi]].]]
Once at Voi, the Master Chief and the Marines began their operation - destroying all anti-air emplacements, in order to allow Pelican drop ships to insert more UNSC forces, including the Arbiter. One emplacement from a perimeter of heavy [[Covenant Air Artillery|Anti-Air Artillery]] was disabled, allowing UNSC [[C709 Longsword-class Interceptor|Longsword]] Fighters and [[UNSC Frigate|Frigates]] to attack the [[Forerunner Dreadnought]]. The [[Prophet of Truth]], however, activated a portal over the "Ark," leading to the true facility - and a Covenant Cruiser made a pinpoint slipspace jump in-atmosphere above Voi, infected by the [[Flood]]
The [[Unnamed Marine Lieutenant|Marine Lieutenant]] commanding forces in Voi soon was forced into a brutal firefight against the Flood, in which he and all of the Marines in his command post were infected, except for [[Suicidal Marine|a single survivor]].

Spartan-117, having destroyed the AA Gun battery, reentered Voi with the Arbiter, and began attacking the Flood and rescuing Marine survivors. Despite his best efforts, only six Marines (plus the Sergeant from the loading ramp and the additional marines from his squad), not counting the traumatized survivor of the raid on the CP or, were rescued. About midway to the crash site of the Flood-controlled ship, the unlikely rescuers of the humans, the First Sangheili Fleet under [[Rtas 'Vadum]], arrived, and deployed [[Special Operations Sangheili]] to assist in the evacuation of John-117 and his Marine squad, and glassing of all infected areas. The Marines that the Chief had been evacuated, and were transported to the Forward Unto Dawn, thus ending major UNSC Marine Corps operations in this area.

===Battle of Installation 00===
{{Main|Battle of Installation 00}}
====Exploration and Touchdown====
{{quote|All armor form up, hit 'em where it hurts!|[[Gunnery Sergeant]] [[Pete Stacker]], leading a Scorpion platoon on the Ark|The Ark (level)}}
Following negotiations between Admiral Hood and [[Rtas 'Vadum]] onboard the [[Sangheili]] flagship [[Shadow of Intent]], it was agreed that the Sangheili Fleet, as well as the Forward Unto Dawn and her Marine complement, would follow [[Truth]] through the Portal to the [[Ark]], after realizing the magnitude of the [[Flood]] threat to all of the galaxy's sentient life and the importance of retrieving the [[UNSC]] A.I. [[Cortana]].

Upon emerging from the Portal, the Sangheili fleet encountered a [[Jiralhanae]] fleet three times their size. With 'Vadum's ships holding the line against Truth's fleet, Spartan-117, the Arbiter, and a Marine-ODST task force under Sergeants [[Avery Johnson]], [[Reynolds]], and [[Pete Stacker]] landed on the Ark.

[[Image:7thHelljumpers.jpg|thumb|ODSTs from the [[7th Orbital Drop Shock Trooper Battalion|7th Battalion]] advance along the [[Ark]].]]
[[Spartan-117]]'s first objective was to clear AA defenses so Commander Keyes could set down the Dawn; he was dropped off with four ODSTs near the first Covenant battery. They proceeded to knock it out, and linked up with two Marines whose Pelican had been shot down. The impromptu assault team hijacked a Jiralhanae Prowler, commandeered a Mongoose from the wreck of the Pelican, and headed out to the last AA battery. Once it was destroyed, Commander Keyes set down the Dawn, and deployed Bravo Team, an armored unit of three Scorpions and a chain-gun warthog under Gunnery Sergeant Stacker, as well as 343 Guilty Spark.

The armored platoon forged ahead, and managed to penetrate a wall separating Spartan-117 from his objective: a Cartographer similar to the one found on [[Installation 04]]. However, a Scarab, a Phantom, and several Wraith tanks were in the way. Bravo Team managed to skillfully bludgeon their way through the Covenant defenses, and Spartan-117 managed to arrive at the Cartographer building, discovering that Truth was holed up in a Forerunner Citadel in the center of the Ark.

====Pathfinding and Confrontation====
Upon the discovery of Truth's location, a flight of five [[Pelican]]s and two Separatist [[Phantom]]s made way to the Citadel. They split up into three groups; the Arbiter led his two Phantoms' worth of Elites, Avery Johnson led a duo of Pelicans filled with Marines, and the Master Chief took another two Pelicans holding [[ODST]]s. Their goal was to split up and quickly deactivate the three shield generators surrounding the Citadel. [[Miranda Keyes]] held back and waited to give the [[Master Chief]]'s team support, fearful of the Anti-Air Wraith guarding their insertion point. Her fears were justified when one of the two Pelicans of the Master Chief's team was shot down. The remaining bird landed the Chief and just three ODSTs to take out the [[Brute]] position and disable the Wraith. Through much hardship and desperation they did just that, and awaited Miranda Keyes' reinforcements of three more Marines, a [[Warthog]] and a [[Mongoose]]. The mounted strike force then fought their way to the interior of the island, towards one of the three generators the battle group was tasked with taking out.

The Master Chief and his team proceeded inside the generator complex, fighting a myriad of loyalist Covenant along the way. The Chief made his way up to the control center, slew a pack of Brutes including a [[Brute Chieftain]], and deactivated the generator. Approximately that same moment, the Arbiter and his Elites deactivated their generator as well. Expecting the third station to fall along with them, Miranda and the Chief were shocked to hear that Johnson's team of Marines was being overwhelmed by Brute reinforcements and were forced to fall back. Keyes rallied the other two strike teams and ordered them to finish the job that Johnson's team had started. 

The team being led by the Master Chief sped back down to their original landing zone, and were picked up by a flight of [[Hornet]]s. Assisted by the remaining two Pelicans, they all battled their way through stiff Covenant air resistance and saw the massive enemy force that had understandingly subdued the now apparently vanished Johnson's team. A vicious landing operation commenced, and the whole cliff side station was violently cleared for the Master Chief and remaining Elites (including the Arbiter) to storm the generator complex and deactivate the final power source. 

As the shield went down, a fully Flood-consumed [[High Charity]] burst out of slip-space (presumably from the portal on Earth) onto the Ark. A number of pieces of debris smashed through the Elites cruiser, severely damaging it. A chunk of infested debris also smashed through the complex, and the Chief fought the Flood as he got back outside to the deployment zone. 

Upon her arrival, Keyes had delivered a [[Scorpion]], a [[Gauss Warthog]], and a few [[Mongooses]] for him to use as he led the remaining Marine ground force and a handful of Elites to the interior of the island and begin the siege of the Citadel. The mounted and heavily armed task force battled their way down the Covenant fortified cliff side and was then met by a terrifying welcome party of two [[Scarab]] tanks. The remaining airborne force of Pelicans and Hornets assisted the Chief's team as they fiercely fought and destroyed this last line of defense. 

The Master Chief and the Arbiter then proceeded into the Citadel to rescue Johnson and kill the Prophet of Truth, but only made it after Miranda Keyes' desperate rescue attempt. Johnson escaped using Miranda's Pelican and returned to [[Forward Unto Dawn]], and the Master Chief and the Arbiter had to fight their way out, escaping the Flood and the Covenant. The remaining Marines and Elites were withdrawn to the [[Shadow of Intent]] as the Master Chief ventured into the remains of High Charity in search of Cortana.

Later, Avery Johnson's exploits aided in the final destruction of the reborn Installation 04 and the Flood, giving his life for Humanity and the Arbiter along the way.

As [[Forward Unto Dawn]] crash-landed into water mass on Earth, Marines (likely those that did not travel to the Ark, or had remained behind with [[Lord Hood]]) helped the Arbiter out of the wreck, and also participated in the memorial ceremony near the Ark Portal. It is likely that Marines were involved in peacekeeping and aid missions on Earth, or sent into space to battle against any remaining Covenant Loyalist forces.

==Uniform==
===Dress Uniform===
The [[Dress Uniform (UNSC Marine Corps)|Marine Corps Dress Uniforms]] are similar to those worn by their 20th and 21st Century predecessors in the [[United States Marine Corps]]. [[UNSC]] Marines wear what appear to be the UNSC's modified and stylized version of the United States Marine Corps emblem on their collars. Furthermore, white jackets and blue trousers are worn instead of the blue dress uniforms of the United States Marines.<ref>''[[Halo 2]]'', ''[[Cairo Station (Level)|Cairo Station]]''</ref> However, in [[2525]], the uniform apparently consisted of a blue jacket and trousers, similar to that of the USMC.<ref>''[[Halo: Contact Harvest]]''</ref>

===Battledress===
[[Image:Halo 3 Marine.jpg|right|thumb|120px|A Marine in the Jungles of Kenya.]]

Marines have few bio-augmentations and usually wear passively [[camouflage|camouflaged]] armored uniforms. They wear dark-colored metal-alloy armor to shield them from gunfire. Marine helmets are mounted with holographic text-displaying eyepieces and [[Helmet Recorder|helmet recorders]]. As well as helmets, Marines on field operations in more humid locales sometimes choose to wear [[Wikipedia:Boonie hat|boonie covers]], or those in colder environments don visored and thicker helmets. 

Marine [[Non-commissioned officer|NCOs]] are easily recognized by the cover that they wear complete with the [[UNSCDF]] insignia, although they oftentimes substitute this soft cover for a more practical protective helmet.

Marines on [[Alpha Halo]] sported gray [[Fatigues (Uniform)|fatigues]], and over that, pieces of brown armor plating covering the head, torso, shoulder, and shins. At times, they only wore their utilities and soft body armor, even forgoing helmets and body armor plating in hazardous combat operations. At times, their helmets were also substituted for boonie covers and sometimes bandannas. However, since they had to get off the ''Pillar of Autumn'', they probably didn't have time to grab their gear. Some Marines had small medical packs built into their back armor plating.

Standard [[M52B Body Armor|Marine battle armor]] appears to be woodland-pattern camouflage utilities, along with an olive drab load-bearing armored vest. The standard-issue armor is uniform than the body armor issued to the Marines on Alpha Halo, as the Marines no longer appear as a rag-tag group of survivors, but as a unified force. They no longer wear boonie covers and are never seen in combat without rigid armor. In fact, the only time Marines were seen without any armor was during the awards ceremony aboard ''[[Cairo Station]]''. In that particular case, they were wearing their white dress uniform.

Another variation of Marine armor is an evolution from that mentioned above, with heavier and well-articulated olive-drab full body armor (armored vest, shoulder plates, elbow pads, and knee pads) over woodland camouflage utilities, allowing them to passively camouflage well in jungle terrain. Marines sometimes don small helmet communications microphones or black-phased sunglasses on their helmets, and others carry backpacks. Marines have been seen to wear black gloves, probably to protect their hands and improve their grip on their weapons.

[[File:ODST2.jpg|thumb|Two [[Orbital Drop Shock Trooper]] special operators clad in their black body suits.]]
[[Orbital Drop Shock Troopers]], otherwise known as "Helljumpers," are a special operations unit within the UNSC Marine Corps. They sport heavy and articulated black [[ODST Battle Armor|Battle Armor]], which are also believed to double as an armored g-suit that allows for safe transport in small ships during turbulent atmospheric entry. They also wear fully-visored black helmets that cover the entirety of the head. This armor provides [[ODST|ODSTs]] with more protection then standard marine armor. Their armor could also take several head shots. 

Marines operating in cold environments wear environmentally-tailored armor, with insulated snow camouflage utilities and full body armor and well as insulated and visored helmets with something analogous to a balaclava.<ref>''[[Halo Wars]]''</ref>

It should be noted that all Marines have a [[HUD]] not just from their helmets, but from their standard [[Neural interface]] which projects HUD data directly to the Marine's retina.

==Equipment==
===Armament===
====Infantry Weapons====
[[File:Sarge beckon.jpg|thumb|Three Marines with various weapons hold out from Covenant forces in a snowy valley.]]
The standard issue weapon for [[UNSC]] Marines Corps is the MA5 series of assault rifles. Most Marines were issued the [[MA5B]] variant until its replacement in late 2552 by the [[BR-55HB SR]] and [[MA5C]].(Note: Before the [[BR55HB SR]] was issued, an older variant called the [[BR55]] was used). Suppressive fire was provided by the [[M247 GP Machine Gun|M247 GPMG]] during the Battle of Earth, presumably replaced by the [[AIE-486H Heavy Machine Gun]] by the time of the Battle of Voi. Special Forces and vehicle crews are issued [[M7 Submachine Gun|M7]] and [[M7S Submachine Gun]] variants, with personal sidearms such as the [[M6 Series]].

Snipers operate the [[Sniper Rifle System 99C-S2 Anti-Matériel|SRS 99C-S2 AM]] and [[Sniper Rifle System 99D-S2 Anti-Matériel|SRS 99D-S2 AM]] sniper rifle variants for anti-materiel and anti-personnel operations, with the [[M99 Special Application Scoped Rifle]] used as a dedicated anti-materiel weapon. Standard UNSC snipers as recalled by [[SPARTAN-117]] usually traveled in a team consisting of two operators (a spotter and a sniper).
Anti-armor fire is provided by the [[M19 SSM Rocket Launcher|M19]] and [[M41 SSR MAV/AW|M41]] rocket or missile launchers and the [[W/AV M6 G/GNR|W/AV M6 G/GNR Spartan Laser]] directed-energy-weapon. Anti-air fire is provided by the [[M19-B SAM Missile Launcher]], capable of destroying [[Banshee]]s and damaging Seraph fighters.

'''Full list'''
*[[MA5B Assault Rifle]] (Standard)
*[[MA5C ICWS Assault Rifle]] (Standard)
*[[SRS99C-S2 AM Sniper Rifle]]
*[[M90 Assault Shotgun]]
*[[M6D Pistol]]
*[[M9 HE-DP Grenade]]
*[[M19 SSM Rocket Launcher]]
*[[M6C Magnum Sidearm]]
*[[BR55 Battle Rifle]] 
*[[BR55HB SR Battle Rifle]] 
*[[SRS99C-S2 AMB Sniper Rifle]]
*[[M41 SSR MAV/AW Rocket Launcher]]
*[[M247 GP Machine Gun]]
*[[M6G Personal Defense Weapon System]]
*[[M7/Caseless Sub Machine Gun]]
*[[M90A Close Assault Weapon System]]
*[[SRS99D-S2 AM Sniper Rifle]]
*[[Spartan Laser|W/AV M6 Grindell/Galilean Nonlinear Rifle "Spartan Laser"]]
*[[M7057 Defoliant Projector]]
*[[NA4 Flamethrower]]

====Ground Vehicles====
The UNSC Marines standard vehicle is the [[M12 Warthog LRV]], used for armored patrols and personnel mobility. The [[M12G1 Warthog LAAV]] is used as an anti-armor vehicle, mounted with an [[M68 Gauss Cannon]], as well as the [[M12A1 Warthog LAAV]] mounted with a [[102mm SC-HE Rocket Turret]], firing 102mm shaped-charge high-explosive rockets. For heavy combat, the Marine Corps operates the [[M808B Scorpion MBT|M808B Scorpion Main battle Tank]], and uses the [[Wolverine]] in an anti-air role.

'''Full list'''
*[[M12 Warthog LRV]]
*[[M12G1 Warthog LAAV]]
*[[M808B Scorpion MBT]]
*[[M831 TT|M831 Troop Transport]]
*[[Mongoose|M274 ULATV Mongoose]]
*[[Elephant]]
*[[Wolverine]]
*[[Rhino]]
*[[SP42 Cobra]]

====Aircraft====
The Corps' most common aircraft is the [[Pelican dropship]], either the [[Dropship 77-Troop Carrier Pelican|D77-TC]] or, in late 2552, the [[D77H-TCI Pelican Dropship|D77H-TCI]] variants, used as multirole aerodynes, able to carry a mixture of [[Scorpion Rocket|Scorpion anti-tank rockets]] and [[ANVIL-II Air-to-Surface Missile|Anvil II air-to-surface missiles]], and equipped with chin mounted 7.62mm Machine-Guns or 70mm Auto-Cannons, Pelicans can also carry [[Warthogs]] and Scorpion Tanks. The Corps also operates the [[Longsword]] as it's primary fighter, using it to its full effectiveness in Air-To-Air, Air-To-Ground, and Space Combat, the [[Hawk]] as a powerful air-to-ground attack gunship, the [[Shortsword]] as a short-range bomber, the [[Attack VTOL-14|Hornet]] aerial support vehicle, and the [[SkyHawk]] VTOL strike fighter.

Marine air units are intended usually to support ground forces or to drop off vital equipment for the Marines, either in close-air-support or air interdiction roles, with the [[UNSC Navy]] or [[UNSC Air Force]] taking on the dedicated air force role<ref>[[Letter - Re:Antilon Mine]]</ref>.

'''Full list'''
*[[D77-TC Pelican]]
*[[AV-14 Attack VTOL]]
*[[Sparrowhawk]]
*[[D77H-TCI Pelican]]
*[[Albatross|Albatross Heavy Dropship]]<ref>[[Sandtrap]] From the Brute Chopper Quicktime video</ref>
*[[Vulture|Vulture Gunship]]

===Miscellaneous Equipment===
*[[CH252 Helmet]]
*[[M52B Body Armor]]
*[[VZG7 Armored Boots]]
*[[S90 Gas Mask]]
*[[Spoofer]]
*[[VX7 Nerve gas]]
*[[PG000E Portable Electricity Generator]]

==Rank Structure==
The rank structure of the UNSC Marine Corps is based around that of the [[United States Marine Corps]].

{{UNSC Officer Ranks}}
{{UNSC Enlisted Ranks}}

==Trivia==
*The equipment and armor used by [[UNSC]] Marines resembles the modern-day US Army's [[wikipedia:future force warrior|Future Force Warrior]] Program, and conceptually may have been inspired by it.
*Bungie went to ''great'' lengths to ensure that the Marines reflected the diversity of Earth; some Marines look and sound American, while others appear [[wikipedia:Asian|Asian]], [[wikipedia:African|African]], [[wikipedia:Australian|Australian]], [[wikipedia:Hispanic|Hispanic]] and [http://en.wikipedia.org/wiki/European European]. Many were also modeled on members of [[Bungie]]'s own staff members to provide further diversity in the universe.
*In the ''[[Halo: Combat Evolved]]'' level [[Truth and Reconciliation (Level)|Truth and Reconciliation]], [[Jacob Keyes|Captain Keyes]] tells a Marine to "''Stow your bellyaching soldier -- remember, you're a leatherneck!''" [[Wikipedia:Leatherneck|Leatherneck]] was a nickname earned by [[wikipedia:US Marines|U.S. Marines]] in the era of the [[Continental Marines]]. The Marines would wear leather collars to provide protection from slashing attacks as they boarded enemy ships.
*In 2007, Bungie hired an actual Marine, [[Christian Allen]], who served with the US Marines from 1995 to 1999, as a Design Lead. Rather than a frontline combat unit, though, he served as a member of the US Marine Corps [[Military Police]].{{fact}}
*In the in-game game mechanics, Marines actually possess regenerating armor that functions similar to the regenerating energy shields possessed by the Master Chief and enemy Elites. Unlike energy shielding, this armor does not have special damage values (i.e. it does not take reduced damage from bullets or increased damage from plasma). In ''[[Halo: Combat Evolved]]'', a Marine's armor is about 50% as strong as a blue Minor Elite's shields. In ''[[Halo 2]]'', the armor appears to be on par with a blue Minor Elite's shielding, allowing a Marine to take roughly the same amount of damage as a blue Minor Elite.
*In [[Halo: Combat Evolved]], shooting a dead Marine's armor with a ballistic firearm would eventually send a ricochet at your shields. Meleeing them would result in a loud "''clack''" However, in ''[[Halo 2]]'' and ''3'', the bullets do not ricochet, but penetrate the dead bodies and result in a large amount of blood. 
*In ''[[Halo 2]]'', Marines receive a significant upgrade in both A.I. and durability. A ''Halo 2'' Marine can survive as much damage as a fully shielded blue Minor Elite, and use intelligent combat tactics (such as using cover and firing from behind cover) that allow small groups of 1 to 3 Marines to hold their own against large squads of Covenant enemies.
*In ''[[Halo 3]]'', Marines generally tend to care greatly about the welfare of the [[Master Chief]], and become scared and upset if you die. However, when playing Co-op with the Arbiter, if the Arbiter dies, the Marines don't seem to care at all and act as if it's unfortunate, but still unimportant.
*In ''[[Halo 3]]'', you can unload a full magazine onto the chest of a marine and they won't even flinch. Their armor really does protect them this time -- but only in the center of the chest. Pilot helmets are also invulnerable, though the visors act as weak spots. Shooting the marines in the helmet for ''Halo 2'' and ''Halo 3'' yield the same results: it will come off. If done with a [[Battle Rifle]], the first shot in the three-round burst will take the helmet off and the other 2 shots will kill him; if you aim right, though, only one shot may connect, allowing you to non-fatally remove the helmet using the Battle Rifle.
*Sometimes in ''Halo 3'', dead Marines and Marines with bandages will have [[Reynolds]]' face.
*In ''[[Halo 2]]'', sometimes if you kill ally Marines until they betray you, they will yell phrases like, "''I have been waiting for this for a long time!''", "''You won't get away with that!''", or "''KILL THE TRAITOR!!!''". In ''[[Halo: Combat Evolved]]'', they will yell out things like "''Let's end this!''", or "''I've had enough of this crap!''" 
* In ''[[Halo 3]]'', when Marines approach fallen Marines, they will crouch beside them, place their hand on the body, and usually utter something like, "''I'll make sure your letter gets to your parents,''" or "'''Better you than me.''" If there are groups of Marines dead, other Marines will, upon discovering the scene, utter things like, "''What happened here?''" or "''Poor buggers, never stood a chance.''" During [[Crow's Nest (Level)|Crow's Nest]], in the Barracks portion of the level, this is a common sight. Marines can also be quite callous when around dead Marines -- particularly with the [[IWHBYD Skull]] activated -- sometimes making statements like, "''He had a watch on him,''" or "''I never liked him anyway,''" or "''Where is that watch?...''"
*There are three crazy marines in the ''[[Halo]]'' trilogy. The [[AWOL Marine|first]] one can be found in the level [[343 Guilty Spark (Level)|343 Guilty Spark]]; the [[Suicidal Marine|second]] one is in [[Floodgate]], and the third one is found in the middle of the [[Halo 3: ODST]] level [[Uplift Reserve (Level)]] behind a makeshift trench.
*In any of the ''[[Halo]]'' trilogy games, Marines will kill an enemy, keep on shooting their dead body and run up to them, yelling things like, "''I saw it move!''" or "''Get up so I can kill you again!''".
*In the new avatar marketplace for Xbox live, you can purchase a marine armor suit for 400 Microsoft points.
*The marines' armor changes drastically from throughout the Halo series, the only thing that stays relatively similiar being the helmet. These changes have yet to be explained canonically.
*In Halo Wars, marines are a unit. Oddly, although your max population is 40, you can train up to 41 marines. The same is true for grunt squads.

==Gallery==
<gallery>
Image:Unsc_icon_3marines_sm.jpg|[[Halo Wars]] [[UNSC]] [[Marines]] render.
Image:Unsc_icon_marines_sm.jpg|Halo Wars Marines.
Image:NewMarines.jpg|Both the standard and Arctic variation of the Marine Battle Dress seen in Halo Wars.
Image:MarineAvatar.png|M5B2 Armor as seen on an [[Xbox LIVE]] Avatar; available for purchase in the Avatar Marketplace along with miscellaneous Halo-related items.
Image:Marines.png|A pair of UNSC Marines in [[Halo Legends]].
</gallery>

==Sources==
{{reflist|2}}

==Links==
===Internal===
*[[United Nations Space Command]]
*[[Orbital Drop Shock Troopers]]
*[[:Category: UNSC Marine Corps Personnel|List of UNSC Marine Corps Personnel]]
*[[List of UNSC Military Units#UNSC Marine Corps|List of UNSC Marine Corps Units]]
*[[UNSC Marine Corps/Gameplay|UNSC Marine Corps in the Games]]
*[[UNSC Marine Corps/Quotes|UNSC Marine Corps quotes]]

===External===
[[Category:UNSC]]
[[Category:Organizations]]