Galaxy Class Starship

Replaced the Ambassador Class Starship as the flagship of Starfleet, and was replaced by the Sovereign Class Starship after the destruction of the Enterprise D above Veridian III in ST: Generations.

This class of ship was created to house a huge number of people while not requiring a large number of crewmen; as a result, the crew's families may live aboard. To prevent a large loss of life in an attack, the saucer section of this starship may disconnect from the drive section and retreat while the drive section continues the battle. Armed with a full spread of phaser banks and three photon torpedo tubes.

According to the Star Trek Technical Manual, the USS Enterprise was the third Galaxy class starship. The first prototype of the Galaxy class was the (aptly named) USS Galaxy, it was followed by the USS Yamato, then the USS Enterprise. The USS Yamato appears in the Star Trek: The Next Gerenation episode Contagion.

Within the onscreen Star Trek universe, it had been long speculated that there were originally six galaxy class starships. Gene Roddenberry, the creator of Star Trek, confirmed the six ship theory. The flagship for the Federation has had a rather unsuccessful run as at least one half of the number produced have been destroyed.

The first ship of the six was the USS Galaxy, the prototype for the line of ships which bears its name. This ship has never been seen in the onscreen universe.

The second ship in the line was the USS Enterprise-D. Registry number NCC 1701-D, this ship was prominently featured in Star Trek: The Next Generation with cameos in the two latter series: Star Trek: Deep Space Nine and Star Trek: Voyager. The Enterprise-D was also featured in the movie Star Trek: Generations, where its battle drive section was destroyed above Veridian IV, and saucer section being unsalvagable on the surface of the planet.

The third ship in the line was the ill-fated USS Yamato. The USS Yamato made a quick appearance in the ST:TNG episode Contagion, as previously supplied by cberube.

The fourth ship in the galaxy class line was the USS Odyssey. The Odyssey appeared in the ST: DS9 episode The Dominion. The ship was part of the task force, comprised of the Odyssey and three runabouts, which traveled into the Gamma Quadrant in response to the newly discovered Dominion. The lack of support was a clear example of how underestimated the resolve of the Dominion was. A Galaxy class starship was more than capable of taking on its strongest peer belonging to the Alpha Quadrant races. A Jem'Hadar warship flew directly into the deflector array of the Odyssey and debris from the intitial impact hit the port nacelle, thus causing a fatal explosion destroying the ship completely. After this display, Starfleet quickly re-evaluated the place for such ships in the fleet. Shortly after this incident, the Defiant, Intrepid, and Sovereign class starships were comissioned, giving Starfleet a much more militant feel to it.

The fifth ship actually seen in the Star Trek universe was an undisclosed ship in the final episode of ST:VOY. Upon leaving the Borg subspace slipstream network, Voyager was shown cruising into a large fleet of ships. One of the ships was a Galaxy class starship. This was the only other time that a galaxy class ship was seen. No identifying features or onscreen dialouge were displayed to identify the ship.

The sixth and final ship in the Galaxy class is an unknown ship that has yet to be seen. However, according to Roddenberry, there was indeed a sixth ship. There is some speculation and possibly an onscreen reference to the sixth ship being destroyed in the battle of Wolf 359 by the Borg. Perhaps they are saving the final ship for a later appearance in the new UPN show Enterprise, the newest incarnation of the Star Trek universe.

Sources:
Star Trek Encyclopedia
My own memory

Galaxy Class Ships have included: USS Galaxy (Conjectural Prototype), USS Yamato (Second ship, Destroyed in TNG "Contagion"), USS Enterprise-D (TNG, Destroyed, ST:7), USS Odyssey (Destroyed, DS9 "The Jem'Hadar"), USS Venture (Appeared in several DS9 Battle Scenes along with at least four other unnamed ships), USS Challenger (Chased the Delta Flyer in an alternate future, VOY).

The TNG Tech Manual says that there were 6 ships in the initial production run, plus an additional 6 produced as just spaceframes which were then put in storage. It is likely that they would have been completed and put into service after Wolf 359 and if any remained they would have been put into service during the Domminion War. Additional Galaxy class ships would probably have been built from scratch.

Even with their limitations in battle, they have cavernous shuttle bays and could be used as mobile starbases. With all the space on board, a battle oriented Galaxy Class could fit a LOT of extra waepons by cutting back on the living space and labs. They would also serve well as transport ships as they can carry over 3000 people (normal crew for an explorer mission is 1000, they could probably operate in battle with fewer than 150).