Rapid Conversion was originally decommissioned by the Sangheili for their own use, but was deemed worthy of use by Jiralhanae. Many of its systems, including weapons and mechanical lifts, were disabled. The crew was compiled of a pack of 10 Jiralhanae, roughly sixty Unggoy and over a hundred Yanme'e responsible for Rapid Conversion's upkeep.
The warship was used to deploy troops and vehicles to the surface of Harvest during the First Battle of Harvest and also used as the Covenant's command center. Though all of its weapon systems had been disabled, the Huragok, Lighter Than Some, was able to unofficially recommission them in time for the ships actions against Harvest and its colonists.
Later, moving into low orbit around Harvest in order to deliver troops and gather the relics they sought, Rapid Conversion fell into a trap laid out by Captain Ponder and his troops and was hit by two rounds from a mass driver based on Harvest's surface. The first round did little damage. The second round, however, passed completely through the warship, severing the connections between the ship's reactor and anti-grav generators, causing the ship to plummet to the planet's surface. However, the crew managed to repair the ship and began to glass Harvest, eventually reducing the planet's surface to cinder. It later destroyed the CMA Argo in orbit. UNSC Battlegroup 4, consisting of CMA Arabia, CMA Vostok, and CMA Heracles was later sent in to investigate, and was nearly wiped out by a Covenant ship over Harvest, possibly the Rapid Conversion or the Covenant battleship that arrived later.
- Halo: Contact Harvest (First appearance)