Editing Barrier tower

{{Status|Canon}}
[[File:Barrier Tower.jpg|thumb|right|250px|One of the barrier towers surrounding the Ark's Citadel.]]
{{quote|We hit these three generators, and the barrier will fall?|[[Miranda Keyes|Commander Miranda Keyes]]}}
'''Barrier towers'''<ref>'''[[Halo 3: The Official Guide]]''', ''page 88''</ref> are [[Forerunner]] structures used to generate protective energy barriers around locations of importance.<ref name="covenant">'''[[Halo 3]]''', campaign level ''[[The Covenant (level)|The Covenant]]''</ref>

Three of these structures surrounded the [[Installation 00 Citadel|Citadel]] on [[Installation 00]], projecting an energy shield that denied access to the Citadel. They could be individually deactivated by means of a [[Holography|holographic]] control panel on their upper floors.{{Ref/Reuse|covenant}} Multiple similar structures were mounted on [[Installation 05]]'s [[Sentinel Wall]], surrounding the [[Quarantine Zone]] around the [[Library]].<ref>'''Halo 2''', campaign level ''[[Sacred Icon]]''</ref>

==Background==
[[Installation 05]] possessed a series of barrier towers placed on top of the [[Library]]'s [[Sentinel Wall]], projecting a shield which can be deactivated manually from within the wall. Superficially, the towers on the Ark somewhat resemble the [[Cartographer]] on the same structure, although they are smaller in size. The beam required to sustain the shield is projected from both the top of the tower's spire and from the bottom.

Like other Forerunner architecture, the towers can be built on a variety of landscapes, as demonstrated by the differences in the towers on Installation 00. The first tower encountered was set in a small valley and had an access tunnel that penetrated through the rock. The second barrier tower was seen to be built in the side of a cliff, and had no entrances other than the ones that led directly into the central room. The final barrier tower was shown to be situated on a small plot of land with ramps that either vehicles or infantry could traverse.{{Ref/Reuse|covenant}}

The towers on Installation 00 also had an observation platform jutting out over them. Inside the control room, there was a large glass window that overlooked the Citadel, surrounded by a semicircular formation of the towers. [[Terminal (Halo 3)|Terminals]] were also shown to be put inside some. The shield that the towers projected was shown to be strong enough to absorb [[plasma turret|plasma torpedoes]] fired from a {{Class|CAS|assault carrier}}. In or around a barrier tower, there is a cavern or tunnel that allows access behind the perimeter. It is possible that each tower has its own power source, as deactivating three barrier towers only allowed "a small section" of the overall shield to fall.{{Ref/Reuse|covenant}}

==History==
===Battle of Installation 00===
[[File:Barrier.jpg|thumb|250px|[[John-117]] deactivating the first barrier tower.]]
{{Main|Battle of Installation 00}}
During the battle of [[Installation 00]] in [[2552#December|late 2552]] between the [[United Nations Space Command]]/[[Swords of Sanghelios|Sangheili]] alliance and the [[Covenant Empire|Covenant]] forces loyal to the [[Prophet of Truth]], the UNSC and the Sangheili sought access to the Citadel, but were barred by means of the energy shield of the three barrier towers. [[Commander]] [[Miranda Keyes]] coordinated a simultaneous assault on all three towers, ordering [[John-117|SPARTAN-117]] and a small [[Orbital Drop Shock Trooper]] and [[UNSC Marine Corps|Marine]] force to take the first east most barrier tower, [[Thel 'Vadam|the Arbiter]] and the [[Sangheili]] to take the middle barrier tower, and for [[Avery Junior Johnson|Avery J. Johnson]] and a Marine detachment to assault the west most barrier tower.{{Ref/Reuse|covenant}}

Each tower was heavily protected. The tower which [[John-117]] was assigned to take out was protected by an [[Ogab'd-pattern anti-aircraft Wraith|Anti-Aircraft Wraith]] and a [[Jiralhanae War Chieftain]] as well as multiple [[Rizsheda-pattern Shade|Shade turrets]], a Wraith, and a [[Jiralhanae Chieftain|Chieftain]] guarding the controls. Johnson's tower was protected by two [[Ogab'd-pattern anti-aircraft Wraith|Anti-Aircraft Wraiths]], one normal [[Zurdo-pattern Wraith|Wraith]], a War Chieftain lookout, a pair of [[Mgalekgolo]] and a swarm of [[Yanme'e]]. The controls were protected by [[Jiralhanae Stalker]]s and a War Chieftain.{{Ref/Reuse|covenant}}

While SPARTAN-117's and the Arbiter's groups managed to deactivate their two assigned barrier towers, Johnson's force ran into heavy Covenant resistance at the third tower, and Johnson's men were killed while Johnson was taken prisoner by the Covenant and taken to the Citadel itself. John-117 was ordered to take a [[AV-14 Hornet|Hornet VTOL]] to attack and land on the third barrier tower, deactivate it and attempt to find Johnson. Even though the Spartan successfully deactivated the last barrier tower, he was unable to find Johnson. Immediately after the third tower's deactivation, the [[The Flood|Flood]]-infested [[High Charity]] appeared and crashed on the Ark's surface nearby. As it went down, it released large chunks of debris, as well as [[Flood dispersal pod]]s, one of which smashed through the window of the tower's control room, allowing numerous [[Flood combat form|combat forms]] and [[Pod infector|infection forms]] to reach the tower and its exterior.{{Ref/Reuse|covenant}} 

Afterward, the shield around the Citadel was lowered and the [[UNSC Marine Corps]] launched an all-out assault on the Covenant-held Citadel.{{Ref/Reuse|covenant}}

==Trivia==
*The [[Halo 3 skulls#Thunderstorm|Thunderstorm]] skull on ''[[Halo 3]]'' can be found on an exterior balcony on the middle barrier tower where the Arbiter and his Elites go in the start of the level, ''[[The Covenant (level)|The Covenant]]''.
*All three of the Forerunner [[Terminal (Halo 3)|Terminal]]s found on the level ''The Covenant'' lie within barrier towers.

==Gallery==
<gallery>
File:H2 Containment Shield.jpg|Barrier-projecting towers on Installation 05's Sentinel Wall.
File:H3-Ark-BarrierTower-Full.jpg|A full view of one of the barrier towers on the Ark.
File:Ark Beam.jpg|A barrier tower on the Ark.
File:Barrier Covenant Battle.jpg|A barrier tower on the Ark during the separatist insertion.
File:Snowy Ring.jpg|Two barrier towers seen during the UNSC/Sangheili assault on the Citadel.
</gallery>

==List of appearances==
*''[[Halo 2]]'' {{1st}}
*''[[Halo 3]]''

==Sources==
{{Ref/Sources}}

==See also==
*[[Forerunner]]
*[[Installation 00]]
*[[Beam emitter]]

{{Forerunner|array}}
[[Category:Forerunner buildings]]
[[Category:Forerunner technology]]
[[Category:Shield technology]]
[[Category:Installation 00 locations]]