UNSC Third Fleet (AAO)

The UNSC Third Fleet is one of four defensive fleets of the UNSC Navy, and is tasked with the defense of Reach.

Reorganization of '53
Initially, both the third and fourth fleets of the reorganized UNSC Navy were designated Patrol Fleets, responsible for guarding and patrolling what remained of the human colonies.

New assignment
In 2570, Third Fleet was officially re-designated as a defensive fleet and given a "new" home - Reach.