More than fifty years after being constructed, it was recommissioned and refitted for military service prior to the period of history known as the Human-Covenant War. The AI on board the Spirit of Fire was known as Serina.
The last civilian captain of the Spirit of Fire was Captain Alexander, who had retired from active duty in the year 2520, on the 20th of July, after colonizing the world of Verent. Directly after his retirement, the vessel was requisitioned by the UNSC and scheduled for refit in order to better prepare it for the combat operations in which it would participate.
Before the First Battle of Arcadia, the Spirit of Fire had visited the planet Arcadia twice, once to aid in the colonization efforts taking place on the planet, and the second time to aid the local authorities in suppressing a violent student riot.
The Spirit of Fire was originally a colony ship, transporting equipment and colonists in the UNSC's expansion efforts. In 2520 the ship was refit with a Magnetic Accelerator Cannon and other armaments to serve as a warship. Huge storage bays that used to house machine parts now carry everything from M12 Warthogs and M808B Scorpions to construction supplies for fire bases involved in front line engagements or in rearguard actions and repair equipment for herself and other ships and crew. In 2530 the Spirit of Fire's thrust assemblies were replaced from the Destroyer UNSC Calcutta, increasing output by 37%.
The Spirit of Fire took part in the Harvest Campaign, providing ground forces with supplies, reinforcements, vehicle support, orbital MAC strikes, air support and more, giving it a major role in the battle.
After the events on Harvest, the Spirit of Fire arrived at the planet Arcadia, where it assisted in the evacuation of civilians, and the eradication of the Covenant from the planet's surface. When Professor Anders was captured by the Arbiter, the Spirit of Fire quickly gave chase, following the Arbiter's flagship to a Flood-controlled planet in an unknown system. This planet eventually turned out to be a Forerunner Shield World, containing a multitude of Forerunner warships. To ensure that the Covenant would not be able to use these warships against humanity, the Spirit of Fire's Shaw-Fujikawa Translight Engine was detonated inside the Shield World's artificial sun. The ship managed to escape the exploding Forerunner installation, but without a slipspace drive, the journey home would take many years, if not decades. Most of the crew entered cryonic sleep at this point, with only a skeleton crew remaining active to run the ship.
On February 10th, 2534, the Spirit of Fire, previously designated as "missing", was declared "lost with all hands" by the UNSC. The reason for this change was kept top secret. A memorial service was held for the people aboard the vessel, but many of the crew's family members chose not to attend, holding out hope that their loved ones are still alive. Various theories circulated throughout the UNSC as to the ship's actual fate, ranging from being lost during a covert mission for ONI, destroyed in orbit over Arcadia, defecting to Insurrectionist forces, or being stranded in space. When Mary Cutter, wife of Captain James Cutter, was asked about the defection theory, she physically assaulted the reporter.
In Halo Wars, the Spirit of Fire can provide various support abilities for the UNSC, some which are universal for the UNSC and specific leader powers, which are often devastating.
These abilities are available to a UNSC faction in skirmish and multiplayer, regardless of which leader you have selected. Compared to leader-specific abilities, these ones are quite passive, and are less effective and less costly.
The Heal and Repair ability slowly restores hit points to all units and buildings within a small radius for a short period of time. The ability costs 350 resources to use, and has a rather medium "recharge" time. This ability most likely represents UNSC service drones from "Spirit of Fire" descending to repair ground and air vehicles.
The Disruption Bomb ability calls in a Shortsword which drops in an unusually large bomb which creates a pulsating, field of blue energy. Within this small energy field leader powers are disabled until the bomb explodes (no collateral damage) after one minute. The target area must be within your line of sight for the bomb to be dropped. The cost for deploying a single disruption bomb is 450 resources.
The Pelican Transport ability calls in a small group of Pelican dropships to quickly transport a group of units to a specific location. Both the pick-up zone and the LZ must be visible within your line of sight for the transport to initiate. It costs only a mere 200 resources, and can be reused several times very rapidly in order to transport large armies, due to a non-existent "recharge" time.
As their labeling may indicate, these abilities are only available if a certain leader is selected. Compared to universal abilities, these abilities are extremely effective, and anything but passive. Due to a greater cost (each one costs 600 resources), and much longer recharge time these abilities are not used as frequently. Unlike universal abilities, each Leader-Specific ability (save for the ODST Drop) can be upgraded three times at the Field Armory, each upgrade tremendously increasing the effectiveness of the ability.
The ODST Drop ability can be used if Captain Cutter is the selected leader. This ability allows you to drop at least a single ODST squad from orbit onto the battlefield, with nearly pinpoint precision. Like all leader powers, the area in which one plans to drop the ODST's must be within your line of sight. Since this ability is constantly "recharging", a player can send as many as ten ODST squads directly to the battlefield. The pods can ONLY be called if you have the ODST Super Unit upgrade, located in the Barracks, and have at least 3 as a minimum tech level. Also, it costs 1 population count and 100 resources to drop a single squad.
The MAC Blast ability is also exclusive to Captain Cutter. This ability fires a number of up to four MAC rounds with amazing accuracy and power to the surface. At first, you can only fire one MAC round per blast, but technologies can be researched at the Field Armory to increase the capacity of MAC rounds up until four MAC rounds per blast. A single shell delivers heavy damage to units within a rather large radius. Like all leader abilities this ability has a very long "recharge" time.
The Cryo Bomb ability can be called in if Ellen Anders is the selected leader. It freezes units temporarily, causing air units to drop and shatter, and make larger units, such as the Scarab, weaker to attacks. The Cryo Bomb is brought by a Shortsword bomber on request.
The Carpet Bomb ability can be called in if John Forge is the selected leader. It releases a double line of bombs along the axis selected by the player, it is capable of destroying several vehicles or squads if used cleverly. The Carpet Bomb is brought by a Shortsword bomber on request.