This unidentified deck gun is a large magnetically accelerated weapon mounted on some United Nations Space Command warships. Given its appearance, it is likely based on railgun technology.
 Service history
In 2520, the Phoenix-class colony ship UNSC Spirit of Fire was outfitted with approximately twenty such weapons. During the Human-Covenant War in 2531, these weapons were often used to provide orbital fire support for the ship's crew.[note 1] During the Battle of Shield 0459, these cannons were used to defend against a Covenant CPV-class heavy destroyer, as well as numerous Spirit dropships and their Banshee escorts, while the ship's Marine and Spartan complement fended off boarders and repaired the drive core.
Two of the deck guns rising out of the Spirit of Fire's interior.
 List of appearances
- ^ a b Halo Wars, campaign level Repairs
- ^ All Halo Wars media, including the in-game timeline, the official website, and Halo Wars: Genesis, state that the Spirit of Fire was outfitted with a single MAC during its military refit. During the cutscene prior to the level Dome of Light, Captain Cutter asks, "Can we use the ship's cannons to take it out directly?" At the end of this level, the player is able to request forty MAC rounds in very rapid succession, which is impossible for a standard MAC; throughout most of the game, the player can request up to four MAC rounds simultaneously. In addition, the rounds released by the "MAC Blast" power cause very limited damage. Thus, it stands to reason that these weapons were used to provide orbital bombardment by the Spirit of Fire rather than its primary MAC, which would cause great collateral damage and would have a considerably lower rate of fire.