The FCS Antrim was a Fox-class WarShip operated by the Federated Commonwealth and one of the force elements contributed to Task Force Serpent in 3059 by the Federated Suns, along with one of the Antrim's sister ships, the FCS Rostock. The FCS Antrim would participate in what became known as the Battle of Trafalgar against forces from Clan Ghost Bear in the Deep Periphery on the 15th of December 3059.
On the 5th of March 3060 the FCS Antrim and the other WarShips within Task Force Serpent engaged in battle with two Vincent Mk 42-class corvettes and a Sovetskii Soyuz-class heavy cruiser above the Clan Smoke Jaguar planet of Huntress. The Antrim survived the battle, although the Rostock was lost.
The Antrim and the Task Force Serpent naval forces were then involved in a second violent naval battle above Huntress against Smoke Jaguar forces retreating from Operation Bulldog in the Inner Sphere; this time, the Task Force faced two more Vincent Mk 42 class corvettes and a powerful Liberator-class heavy cruiser. The Antrim took heavy damage in this battle, damage which couldn't be repaired in the field.
The Antrim survived the conflict with the Smoke Jaguars and returned to the Inner Sphere, and estimates of the repair work being conducted in 3062 indicated that the Antrim was expected to return to active service in early 3063. The crew of the Antrim chose to remain loyal to Archon Katherine Steiner-Davion during the FedCom Civil War, and as a result the Antrim was a participant in the last WarShip battle of the Civil War, fought above New Avalon in 3066.
The Antrim joined two Avalon-class cruisers, the FCS Lucien Davion and FCS Alexander Davion, and another loyalist Fox, the FCS Murmansk, in the defense of New Avalon against the task force led by Victor Steiner-Davion. The attacking forces were led by the Avalon-class FCS Melissa Davion and no less than four Foxes - the FCS Admiral Corinne Donnings, FCS Kentares, FCS Intrepid and FCS Robinson. The result was an hour-long naval battle that saw three WarShips destroyed (the Alexander Davion, Admiral Corinee Donnings and Kentares) and the the surrender of the Lucien Davion and Antrim.
After the FedCom Civil War the Antrim remained in service with the Federated Suns as the FSS Antrim. In October 3067 the Antrim was guarding New Avalon alongside a sister ship, the FSS Bryceland, when a trio of Word of Blake WarShips appeared. The three Blakist WarShips - the Essex-class destroyer WoBS Divine Forigveness, Riga-class frigate WoBS Red Angel and the Aegis-class heavy cruiser WoBS Herald of Justice had been positioned in the outskirts of the New Avalon system along with orders to jump to New Avalon and reveal themselves as the new defenders of the Federated Suns capital world after the Word of Blake had been accepted into the Second Star League. The collapse of the Second Star League ahead of the vote saw the three ships issued new orders; to punish the Federated Suns. The Antrim and Bryceland attempted to interdict the Blakist fleet as it approached New Avalon, and managed to cripple and then destroy the WoBS Herald of Justice via suicidal collisions but despite the heavy fighting in space the AFFS could not prevent the Word from bombarding Avalon City and dropping almost a division of ground troops onto the city.
- Twilight of the Clans, p. 8, "Task Force Serpent Composition"
- Twilight of the Clans, p. 9, "Beyond the Periphery"
- Twilight of the Clans, p. 10, "The Conquest Begins"
- Twilight of the Clans, p. 12, "The Conquest Continues"
- Field Manual: Federated Suns, p. 25, "AFFC WarShip Fleet"
- FedCom Civil War, p. 170, "New Avalon"
- Field Manual: Updates, p. 124, "WarShips of the AFFS"
- Total Chaos, p. 43-45, "New Avalon (sidebar)"
- Jihad: Final Reckoning, p. 44, "The Jihad In Review"
- Jihad: Final Reckoning, p. 128, "Original Word Of Blake Fleet"