Despite being occupied for a time by the Covenant, the Pillar was soon abandoned even by them and since it had been emptied of nearly all its cargo then it was largely useless for the majority of the actual battle. However, Zuka Zamamee and Yayap visited the Autumn during their jaunt across the ring. The Flood inhabited the ship for a time, and they tried to repair the craft and use it to escape the ring, despite the limited resources.Eventually, the ship was visited by Johnny and Cortana in their attempt to destroy the ring, but Guilty Guilty disabled all command access and so they had to manually blow the slag out of the engine cores before the ship finally decided that it just wanted to blow up. As Johnny and Cortana fled in a Longsword and Guilty Guilty flew out of a window, The Autumn exploded, taking a large chunk of Halo with it. This caused the entire ring to splinter and shatter, destroying an entire Covenant Armada and ending the Covenant threat temporarily.
Physically huge, the Pillar of Autumn was a ship of a discontinued line of Heavy Cruisers - the Halycon-class - that was refitted for a special mission on REAAAACH!!!!. It was this added Reachiness that allowing the Pillar of Autumn to triumph over the Covenant threat. Despite being old, it was able to withstand several Covenant Plasma Torpedoes before crashing on the ring and it was powerful enough to blast the ring to pieces.
A small fragment of the Pillar of Autumn now rests in the Museum of Unnatural History.