Editing M68 Gauss cannon

{{Status|Canon}}
{{Disambig header|Gauss cannon featured in ''[[Halo 2]]'' and ''[[Halo 3]]''|other Gauss cannon models|Gauss cannon}}
{{Weapon infobox
|name=M68 Asynchronous Linear-Induction Motor
|image={{Pageimage|HTMCC-HR Kat&Gauss 1.png}}[[File:Gauss turret.png|300px]]
|manufacturer=[[Misriah Armory]]{{Ref/Book|Id=Enc22|Enc22|Page=181}}
|series=
|type=[[Gauss cannon]]
|cost=
|variant=
|service=
|length={{Convert|9.7|ft|m|disp=flip|sp=us}}{{Ref/Reuse|Enc22}}{{Ref/Note|Id=disrepancies|See [[#Production notes|production notes]] for disrepancies}}
|width=
|height=
|weight={{Convert|243|lb|kg|disp=flip|sp=us}}{{Ref/Book|Id=Enc11|Enc11|Page=321}}
|ammotype=[[25x130mm]] ferric-tungsten slug{{Ref/Reuse|Enc22}}
|capacity=750 rounds{{Ref/Reuse|Enc11}}
|feed=
|operation=[[Coilgun]]
|rate=
|velocity=[[Wikipedia:Hypersonic speed|Hypersonic]]{{Ref/NoteReuse|disrepancies}}
|optics=
|range={{Convert|8|km|mi|sp=us}}{{Ref/Reuse|Enc11}}{{Ref/Novel|Id=OB1|Oblv|Chapter=1}}
}}
The '''M68 Asynchronous Linear-Induction Motor''' is a model of [[Gauss cannon]] used by the armed forces of the [[United Nations Space Command]]. While overshadowed by its more common [[M68B Gauss cannon|M68B variant]], the M68 was used during the [[Human-Covenant War]] as an anti-armor weapon capable of firing hypervelocity, high-density projectiles. Also known among the troops as the "68," "Rail Gun," "Tent Pole," and the "Gas Gun,"{{Ref/Reuse|Enc11}} it can be mounted on a stationary stand, or mounted on a vehicle. In the vehicle-mounted role, it is most famous as an armament on the [[M12G1 Gauss Warthog|M12G1 "Gauss" Warthog]].

==Overview==
===Design details===
Despite its name, the M68 does not operate as a [[Wikipedia:Gauss gun|Gauss gun]], instead named after the 19th century mathematician [[Wikipedia:Carl Friedrich Gauss|Carl Friedrich Gauss]] - the pioneer for the underlying technology behind the weapon.{{Ref/Site|URL=http://halo.xbox.com/en-us/intel/related/gallery/gauss-technology/71304700-12eb-4ab5-9fe7-a52e4ca4094f|Site=Halo Waypoint|Page=Gauss Technology|D=06|M=10|Y=2011|LocalArchive=Archive:Halo Waypoint/2009 to 2014/Universe/Technology#Gauss Technology}}{{Ref/Book|Id=EVG|EVG|Page=78}} As with other Gauss cannons, the M68 fires using [[Wikipedia:Linear motor|asynchronous linear induction motors]]; using staged electromagnets that turn on-and-off in sequence to accelerate the projectile inside the barrel up to [[Wikipedia:Hypersonic speed|hypersonic velocities]].{{Ref/Reuse|Enc11}}{{Ref/Book|Id=Enc22p137|Enc22|Page=137}}{{Ref/Site|Id=Enc22Glossary|URL=https://www.halowaypoint.com/news/the-new-halo-encyclopedia-is-out-today|Site=Halo Waypoint|Page=The New Halo Encyclopedia is Out Today|D=16|M=03|Y=2025}} {{Ref/Novel|Id=OB3|Oblv|Chapter=3}} In practice, this is similar to the much larger [[naval coilgun]] turrets and [[Magnetic Accelerator Cannon]]s used on [[UNSC starship]]s as heavy [[Space warfare|space combat weapons]], or the smaller [[M99 Stanchion|Stanchion]] series of handheld coilgun anti-materiel weapons. In this respect, it is sometimes informally termed a "mini-MAC".{{Ref/Anthology|Id=PH|Evo|Palace Hotel}}

The weapon overall measures {{Convert|9.7|ft|m|disp=flip|sp=us}} in length,{{Ref/Reuse|Enc22}}{{Ref/NoteReuse|disrepancies}} with a barrel length of {{Convert|2|m|ft|sp=us}}.{{Ref/Reuse|OB3}} It has a very similar design to the older [[M65 Gauss cannon]] used by the [[Colonial Military Authority]], though unlike the M65 has a re-centred optics module and an integrated body shield that can protect the operator from incoming frontal fire.{{Ref/Reuse|Enc22}} The optics module consists of two large lenses which are connected to a firing computer in the weapon itself. The user is displayed a screen that shows a readout of what the gun can see alongside a [[heads-up display]] for aiming.{{Ref/Game|H3|Gauss Turret in-game weapon}} The Gauss cannon is additionally capable of [[smart-linking]] to a heads-up display such as that in [[MJOLNIR Powered Assault Armor]], allowing an operator to project the weapon's [[reticle]] even when the optics package is not available.{{Ref/Reuse|OB3}}
[[File:Old HW Gauss 2.png|thumb|250px|The Gauss cannon's distinctive blue-white trail is caused by superheating of the air around the projectile.]]
When fired, the Gauss cannon's projectiles cause an ear-splitting sonic boom as they accelerate{{Ref/Reuse|OB3}} - personnel stood within {{Convert|66|ft|m|disp=flip|sp=us}} of the weapon when it is fired may suffer permanent hearing damage if they do not have hearing protection.{{Ref/Reuse|Enc11}} As the projectile travels through the air, it emits a burst of intense blue-white light due to the friction of the round heating up.{{Ref/Reuse|OB3}} The speed of the projectile is such that they appear instantaneous to the [[human]] eye,{{Ref/Reuse|Enc22}} and impact their target before the operator has even finished pulling the trigger.{{Ref/Reuse|OB3}}

===Ammunition===
The M68 Gauss cannon fires a ferric-tungsten [[25x130mm]] round. These are fed into the weapon by a rotating cylindrical magazine towards the back of the barrel capable of holding 750 rounds.{{Ref/Reuse|Enc11}}

There are a number of ammunition types available, depending on use case.
*25x130mm Armor-Piercing, Limited Penetration/Frangible (APLP/F){{Ref/Reuse|Enc11}}
*M485 25x130mm High-Velocity/Ferric-Tungsten Hollow-Point Projectile (HV/FTHPP).{{Ref/Reuse|Enc22p137}}{{Ref/Reuse|Enc22Glossary}}

===Variants===
There are half a dozen design variants of the M68 ALIM platform, all of which are produced by Misriah Armory.{{Ref/Reuse|Enc22p137}} However, the most common is the [[M68B Gauss cannon|M68B variant]] of the Gauss cannon - one which eclipsed the standard M68 and became the most commonly-used Gauss cannon of both the [[UNSC Army]] and [[UNSC Marine Corps]] during the [[Human-Covenant War]]. The M68B has a distinctive silhouette, with a bulkier power feed architecture and cooling system.{{Ref/Reuse|Enc22}}
<gallery>
File:HTMCC-HR Kat&Gauss 1.png|[[Catherine-B320]] operating an M68B Gauss cannon during the [[Battle of Sword Base]].
File:H4 gauss hog render.png|An M68B Gauss cannon mounted on an [[M12B Warthog]] chassis.
</gallery>

===Usage===
[[File:Old HW Gauss 1.png|thumb|250px|[[John-117]] firing an M68 mounted to a Warthog during the [[Battle of the Citadel]].]]
The M68 was originally introduced into UNSC service to provide anti-armor and anti-materiel support over long distances. However, the versatility and control of the emplacement ultimately made it a principle component of mechanised vehicle [[squad]]s specialising in hunter-killer and anti-[[tank]] roles.{{Ref/Reuse|Enc22}} They may also be used in a limited anti-aircraft role; Gauss Warthog teams attached to remote units drill for use in both anti-tank and anti-air duties.{{Ref/Game|H5G|List of REQ cards|REQ card|Detail=Tundra Gauss Warthog|Quote=Gauss Warthogs attached to remote garrison units serve as both anti-armor and anti-aircraft vehicles, and their driver/gunner pairs drill for both tasks. Improved Gauss Warthog with extra armor.}}

The Gauss cannon's intended role is similar in nature to that of the [[M39 rocket turret]], with both the M12G and [[M12A Rocket Warthog|M12A Warthogs]] respectively having the formal designation of '''Light Anti-Armor Vehicle'''. The turret's versatility means it can be employed on any vehicle capable of accepting a standard Warthog turret; this includes the aforementioned M12G Warthog, the [[M650 Mastodon]] and the [[M35 Cougar]] - the latter of which boasting dual M68s in a rotating turret atop the vehicle. Stationary mounts are also used.{{Ref/Game|H3ODST|Gauss Turret in-game weapon}}

==Operational history==
M68s were used throughout the entirety of the [[Human-Covenant War]], from its earliest battles to the [[Battle of Installation 00|final engagement]] of the conflict on [[Installation 00]]. In [[2526]], a half-dozen Gauss cannons were used by [[SPARTAN-II program|Spartan-II]] [[Blue Team]] during the [[Battle of Mesra]]. During the fighting, the [[Militia of Mesra]]'s Gauss Warthogs were destroyed, leading to Blue Team tearing the M68 cannons off the vehicles and using them as handheld weapons. Due to the sheer size of the Gauss cannon, they could only be fired prone, leading Blue Team to set up firing positions in the [[Karpos Mountain Range]] overlooking the [[Samalat Gorge]]. From here, they used their Gauss cannons to fire down on a large [[Covenant]] convoy of [[Wraith]]s, [[Combat bridging vehicle|bridging vehicles]] and [[Combat support vehicle|support vehicles]], before being forced to retreat by the enemy's [[Yanme'e]] defences.{{Ref/Reuse|OB1}}{{Ref/Reuse|OB3}} M68s also played a role in the [[Harvest campaign]], and were heavily used by the ground forces deployed by {{UNSCShip|Spirit of Fire}} throughout [[2531]] including the aforementioned war on [[Harvest]] alongside the [[Battle for Arcadia]] and [[Battle of Trove]].{{Ref/Game|HW|Gauss Turret in-game weapon}} Sergeant [[John Forge]] in particular deployed into battle using a Gauss Warthog, often choosing to man the gun directly.{{Ref/Level|HW|Arcadia City}}{{Ref/Novel|Halo: Hippocratica}}

Towards the end of the war, M68 Gauss cannons were used in the [[Battle for Earth]], seeing use by [[John-117]] and by the defenders of the [[ONI Alpha Site (location)|ONI Alpha Site]] in the early stages of the [[Battle of Mombasa]].{{Ref/Level|H2|Metropolis}}{{Ref/Level|H3ODST|ONI Alpha Site}}{{Ref/Level|H3ODST|Coastal Highway}} They continued to be used later after UNSC-[[Covenant separatists|seperatist]] forces deployed to the Ark, being used in the push for the installation's [[Cartographer]] and later, the [[Citadel]].{{Ref/Level|H3|The Ark (level)|The Ark}}{{Ref/Level|H3|The Covenant (level)|The Covenant}}

During the [[Carrow Conflict]] in [[2556]], Spartan [[Gray Team]] used an M68 in combination with a [[HAVOK tactical nuclear weapon]] in order to create a weapon capable of firing an [[electromagnetic pulse]]. The [[nuclear weapon]] was used to provide additional power for the Gauss gun, while the weapon itself was modified to emit the EMP.{{Ref/Novel|Env|Chapter=22}} It was used against [[Hekabe]] and his [[Sharquoi]] legion by disabling the [[Forerunner]] technologies that enabled their control, though after firing once the gun was burnt out.{{Ref/Novel|Env|Chapter=25}}

==In-game information==
{{Main|Gauss Turret (gameplay)}}
[[File:HTMCC-H3ODST Dutch M68.png|thumb|250px|[[Taylor Miles]] using a stationary M68 Gauss turret at [[ONI Alpha Site (location)|Alpha Site]], [[New Mombasa]].]]
The Gauss Cannon made its in-game debut in ''[[Halo 2]]'', first showcased in the ''[[Halo 2 E3 demo]]'' and using the design of a rocket launcher cut from ''[[Halo: Combat Evolved]]'' (see [[#Production notes|production notes]] for more details). It functions as an extremely powerful turret that can kill enemy heavy vehicles in a handful of a shots. Since then it was featured in ''[[Halo 3]]'' and ''[[Halo 3: ODST]]'' fundamentally unchanged, though ''ODST'' introduced a stationary turret variant of the weapon, allowing it to be used in circumstances outside of on the back of a Warthog.

In ''[[Halo Wars]]'', the M68 is featured as the final upgrade available for the Warthog unit. It can be purchased at the [[Firebase]] with the following requirements:
*Info: Upgrades Warthog machine gun to a gauss cannon. Improves damage and defense. 
*Tier: {{HWTech|3}}
*Cost: {{HWPop|0}}, {{HWResources|800}} {{C|400 for [[Ellen Anders|Professor Anders]]}}

In later games from ''[[Halo: Reach]]'' onward, the M68 Gauss cannon was replaced by the [[M68B Gauss cannon]] and [[M70 Gauss cannon]].

==Production notes==
The Gauss cannon's design originates in the [[Pre-Xbox Halo|pre-Xbox]] era of ''[[Halo: Combat Evolved]]''{{'}}s [[Development of Halo: Combat Evolved|development]]. At this early stage of production, ''Halo'' was intended to feature a [[Cut Halo: Combat Evolved vehicles#Rocket Warthog|Rocket Warthog]], fitted with a turret with an extraordinarily similar design to that of the M68 Gauss cannon. The Rocket Warthog was ultimately cut from ''Halo'', with an [[M39 rocket turret|alternate rocket turret]] design created when the game was [[Halo: Combat Evolved (PC port)|ported to PC]]. As such, when ''[[Halo 2]]'' was in production, the Rocket Turret's design was brought back, now-reworked as the Gauss cannon.

According to [[Bungie]] designer [[Tyson Green|Tyson "ferrex" Green]], the Gauss cannon's ''Halo 2'' sound effects were taken from that of a [[railgun]] firing. This was intentional, as the railgun's sound effects were "too cool not to use", despite operating on a different electromagnetic principle.{{Ref/Site|URL=http://www.bungie.net/Forums/posts.aspx?postID=27004812|Site=Bungie.net Forums|Page=Subject: I found why the wrthog gauss cannon is called gauss.|Quote=While the Warthog gauss rifle is modeled as a magnetic acceleration cannon, the sound and effects are actually those of a railgun, which operates on a different principle. However, the sound and effects were so cool that we couldn't not use them.|Quotee=Tyson Green|D=26|M=03|Y=2009}}
<gallery>
File:HCE CutRocketHog Screenshot 2.png|The cut Rocket Turret.
File:HCE CutRocketHog Screenshot 3.png|The cut Rocket Turret, aft view. Note the exhaust tube extending behind the operator's shoulder; in ''Halo 2'' this was reworked and replaced with the Gauss cannon's rotary magazine.
</gallery>

===Disrepancies===
*The muzzle velocity of the M68 has been up for some dispute between sources. Early sources including the ''[[Halo: Evolutions]]'' short story ''[[Palace Hotel]]'' and ''[[Halo: The Essential Visual Guide]]'' note the Gauss cannon's muzzle velocity to be Mach 40 - a massive number well beyond the escape velocity of Earth, and unrepresentative of the cannon's projectile seen in the ''Halo'' games.{{Ref/Reuse|EVG}}{{Ref/Reuse|PH}} More recent sources, including the [[Halo Encyclopedia (2009 edition)|2009]], [[Halo Encyclopedia (2011 edition)|2011]], and [[Halo Encyclopedia (2022 edition)|2022 editions]] of the ''Halo Encyclopedia'' alongside the novel ''[[Halo: Oblivion]]'', have toned down this figure significantly, noting that Gauss cannons fire their projectiles at [[Wikipedia:Hypersonic speed|hypersonic speeds]] - AKA Mach 5 or over.{{Ref/Reuse|Enc11}}{{Ref/Reuse|Enc22p137}}{{Ref/Reuse|OB3}} However, one page of the ''2022 Encyclopedia'' seemingly-erroneously mentions the M68 as firing at speeds "''approaching Mach 1''" - an unrealistically low figure that may be a typo intended to say ''Mach 10''.{{Ref/Reuse|Enc22}} As such, this page uses the "hypervelocity" statements as the most consistently-depicted fact.
*In the [[Halo Encyclopedia (2009 edition)|2009]] and [[Halo Encyclopedia (2011 edition)|2011 editions]] of the ''Halo Encyclopedia'', the M68's length was noted as {{Convert|114.7|in|cm|disp=flip|sp=us}}.{{Ref/Reuse|Enc11}} This figure was updated in the 2022 edition to {{Convert|9.7|ft|m|disp=flip|sp=us}}.{{Ref/Reuse|Enc22}}

==Gallery==
{{linkbox|gallery=yes}}
<gallery>
File:H2-M68ALIM-GaussCannon.png|The M68 ALIM in ''Halo 2''.
File:H2-GaussHUD.png|HUD of the M68 in ''Halo 2''.
File:H2 E3 2004 Warthog.jpg|The M68 Gauss cannon in the ''[[Halo 2 E3 Multiplayer Demo]]''.
File:Ammo -Gauss.png|A Gauss slug of the M68 Gauss cannon from ''[[The Art of Halo 3]]''.
File:HTMCC H3 GaussCannon SideView.png|A side view of the Gauss cannon in ''[[Halo 3]]''.
File:Halo3GaussHogLastResort.jpg|A Gauss Warthog on [[Last Resort]] in ''Halo 3''.
File:H3-GaussHUD.png|HUD of the M68 in ''Halo 3''.
File:Gaussshot.jpg|A closeup of a Gauss cannon's projectile in the air. Note that the contrail starts out blue but fades to yellow in ''Halo 3''.
File:HTMCC-H3 Dubbo on a Gauss Hog.jpg|A Marine fires a Gauss cannon in ''Halo 3''.
File:Old HW Gauss 2.png|John-117 firing a Gauss cannon in ''Halo 3''.
File:H3ODST-StationaryGauss-Reference.png|Turnaround reference image of the mounted stationary Gauss cannon in ''Halo 3: ODST''.
File:Stationary Gauss Cannon.JPG|The stationary variant of the Gauss cannon in ''Halo 3: ODST''.
File:H3ODST Rookie&GaussCannon.jpg|The [[Jonathan Doherty|Rookie]] inspecting a destroyed Gauss cannon in ''Halo 3: ODST''.
File:HW-M12G1svsInnies.png|Gauss cannons in ''[[Halo Wars]]''.
File:HTMCC-HR Kat&Gauss 2.png|Kat fires a Gauss cannon at a {{Pattern|Rizvum|Revenant}} in ''Halo: Reach''.
File:HTMCC-HR GaussCannon Firing.png|The Gauss cannon's projectile in ''Halo: Reach''.
</gallery>

==List of appearances==
*''[[Halo 2]]'' {{1st}}
*''[[Halo: Uprising]]''
*''[[Halo 3]]''
*''[[Halo Wars]]''
*''[[Halo 3: ODST]]''
*''[[Halo: Evolutions - Essential Tales of the Halo Universe]]''
**''[[Palace Hotel]]''
*''[[Halo: Envoy]]''
*''[[Halo: Retribution]]'' {{Mo}}
*''[[Halo: Oblivion]]''
*''[[Halo: Hippocratica]]''

==Notes==
{{Ref/Notes}}

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

{{UNSC heavy weapons}}
[[Category:Magnetic acceleration weapons]]
[[Category:UNSC ground weapons]]