A Fortress Ship (also called a Star Carrier) combines the best features of a Dreadnought and a Fleet Carrier, and serves as a mobile base for smaller ships. This class of ship is so massive, it count as a space station in size, but is mobile--if extremely slow--and can gradually achieved the momentum needed to make a jump. It is armed with an impressive main battery, and it embarks numerous small craft, too. At least two Fortress Ships were built in the post-Second Sathar War era: UPFS-FS01 Morgaine of Task Force Prenglar, and SPFS-FS02 Gabriel of Task Force Cassidine. Like any super-heavy warships, fortress ships are national assets that serve as the centerpieces of the sector's defense fleets; they’re almost always accompanied by an escort of dozens of warships--cruisers and destroyers. In addition to its normal cargo capacity, a star carrier can hold over 16 fighters.
(material based on Richard Baker's Warships text for Alternity, and D20 Future)