Fleet Group Three was one of three major fleets in service with the New Republic Defense Force at the time of the Battle of Coruscant. Commanded by General Wedge Antilles from the Star Destroyer Mon Mothma, it was to be the hammer to the anvil of Fleet Groups One and Two. It suffered the fewest losses during the engagement due to General Antilles' reluctance to engage refugee ships that were being forced to ram themselves against Coruscant's planetary shield by the Yuuzhan Vong fleet. Thousands of his ships defected to General Garm Bel Iblis's Fleet Group Two as a result of their fleet commander's refusal to engage.
When a retreat was called at Coruscant, a vanguard force from Fleet Group Three jumped to Borleias and managed to rout the Yuuzhan Vong occupational force, retaking the planet for the New Republic. Antilles planned to make that world a temporary haven for the billions of refugees fleeing the galactic capital, but the self-declared Chief of State Pwoe and the rest of the Advisory Council followed the fleet to Borleias and ordered General Antilles to remain on-world indefinitely in order to harass the Vong. In reality, Pwoe wanted Antilles and his fleet to sacrifice themselves, thus giving him time to prepare for a formal surrender to the Vong. Antilles saw right through the rogue Senator's plans and managed to blackmail him into allowing the rest of Fleet Group Three and the Star Dreadnought Lusankya to join him at Borleias.
Although Lusankya managed to destroy one of the Yuuzhan Vong battle groups that had been sent to subdue the Republic at Borleias, it and Fleet Group Three were besieged for months by an even larger force led by Commander Czulkang Lah, father of the current Warmaster, Tsavong. The Battle of Borleias ended with Fleet Group Three's complete withdrawal, but only after the destruction of Czulkang Lah's worldship and the majority of the Vong fleet. Afterward, the fleet was reorganized due to attrition, merging with the Third Battle Group and bearing the redesignation of Third Fleet as part of the newly-formed Galactic Alliance Defense Force.
- The New Jedi Order: Star by Star (First appearance)
- The New Jedi Order: Enemy Lines I: Rebel Dream
- The New Jedi Order: Enemy Lines II: Rebel Stand