From Halopedia, the Halo wiki
In 2525, the Commonwealth ferried the SPARTAN-IIs along with Catherine Halsey to the Damascus Testing Facility on the planet Chi Ceti IV. There, during the Battle of Chi Ceti, the Commonwealth successfully engaged the Covenant ship Unrelenting. With the assistance of the Spartan-IIs' boarding party, and their new MJOLNIR Mark IV armor, the Commonwealth was able to destroy the light cruiser. The Commonwealth, however, was severely damaged in their first engagement against the Covenant and shortly thereafter rendezvoused with the UNSC Persian Gate to transfer the Spartans and Dr. Halsey to the ship.
Damage sustained at Chi Ceti IV
The ship took heavy damage during the Battle of Chi Ceti. The damage was:
While it was not structural damage, the Commonwealth lost Longsword Squadron Delta in its entirety while pulling away from the Unrelenting to escape the blast of a nuclear warhead.
Decommissioning and scrapping
Some time between the Chi Ceti incident and 2552, the Commonwealth was decommissioned by the UNSC and was landed at the Asźod ship breaking yards to be scrapped.
When the Epsilon Eridani system was attacked, the Commonwealth became a battlefield venue between the ground forces of the UNSC and the Covenant during the Battle of Asźod. On August 30, SPARTAN-B312 and Emile-A239 pushed through the ship's stripped wreckage in order to deliver a vital package to the UNSC Pillar of Autumn.
At the time of the attack, the Commonwealth was well into being scrapped. Already, its entire port-side launch deck was removed, along with its port engines. Its bridge had been taken out, and holes were made on its underbelly to allow staircases to be fitted in for the technicians assigned to take it apart.
Several parts of the Halo: Fall of Reach - Covenant depicts Commonwealth as a Stalwart-class light frigate and Charon-class light frigate instead of the canonical Paris class by regarding the frigate model being identical with frigates in Halo 2 and the hangar being similar than that of the frigates in Halo 3.
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