Editing Mark 2551 Onager

{{Era|Post}}

|length={{Convert|32.6|m|ft}}<ref name="VIS"/>

|width={{Convert|12|m|ft}}<ref name="VIS"/>

|height={{Convert|10.4|m|ft}}<ref name="VIS"/>

|ammotype=25cm M6792 HV/FTHPP-AS<ref name="VIS">'''[[Halo 4: The Essential Visual Guide]]''', ''page 75''</ref>

The '''Mark 2551/25cm Portable Magnetic Accelerator Cannon''', also known as the '''Onager''', is an upgraded variant of the [[Mark 2488 Magnetic Accelerator Cannon]] developed by [[Misriah Armory]]. It uses a 25cm ferric-tungsten depleted uranium round that is fired at hypersonic speeds.  

The UNSC's postwar prototype flagship, {{UNSCShip|Infinity}}, is equipped with a number of Mark 2551 MAC dorsal turrets. During [[Battle of Requiem|the initial battle]] on the [[Forerunner]] [[shield world]] [[Requiem]] in [[2557]], the "MAC network" controlling these turrets was disabled by troops of [[Jul 'Mdama's Covenant]] fighting for the [[Ur-Didact|Didact]], through the use of three jamming devices placed on the ''Infinity'''s hull. Once these jammers were destroyed by [[John-117]], [[Cortana]] successfully brought the network back online in a few minutes, though a link relating to "EM relays" needed to be manually initiated before they could fire. When they did, they successfuly forced the Didact in his [[Cryptum]] and his allies to retreat. Along with ''Infinity's'' anti-aircraft batteries, the turrets shot down at least two {{Class|CRS|light cruiser}}s.<ref name = "H4L4">'''[[Halo 4]]''', campaign level ''[[Infinity (level)|Infinity]]''</ref>

[[Office of Naval Intelligence|ONI]]'s [[Ivanoff Station]] near [[Installation 03]] made use of several automated Mk. 2551 Onagers for defense against space debris and later against at least three [[Jul 'Mdama's Covenant faction|Covenant]] {{Class|CRS|light cruiser}}s when the station was [[Raid on Ivanoff Station|attacked]] by Covenant forces under the command of the Didact himself. The station's defenses were reprogramed by [[Cortana]] to give the evacuating personnel covering fire against the attacking Covenant forces. The Onagers shot down multiple approaching Phantoms, though some managed to slip through their defensive fire to land troops on the station.<ref>'''[[Halo 4]]''', campaign level ''[[Composer (level)|Composer]]''</ref>

File:H4_Onager_Concept.jpg|Concept art of the Mark 2551 MAC.

File:H4-OnagerMDC-ScanScreen.jpg|Mark 2551 MACs on the hull of UNSC ''Infinity'' and on Ivanoff Station

File: Mk 2551 Onager.jpg|An Onager firing at a {{Class|CRS|light cruiser}} during the [[Battle of Aktis IV]].