The EF76 Nebulon-B escort frigate was a 300-meter-long warship that was built by Kuat Drive Yards for use by the Imperial Navy, to protect convoys from Rebel Alliance starfighter actions. It was, however, used more famously by the Rebellion.
While generally well-armed for a vessel of that size, the midsection connecting spar was an exploitable vulnerability. It could be split open by concentrated heavy weapons fire, venting the frigate's atmosphere and killing most of the crew.
The EF76 was introduced as a counter-insurgency ship after the Clone Wars. It largely phased out the Class-C frigate. The Nebulon-B was originally designed to defend Imperial convoys against raids by Rebel starfighters, as the Imperial Navy wasn't keen on the idea of relegating its expensive Imperial-class Star Destroyers to escort duty, and the CR90 corvettes were too weak and carried few, if any, TIE Fighters.
The EF76 was used extensively by both sides in the Galactic Civil War. The frigate was known and respected for its efficiency against fighters and bombers, and its anti-fighter assignment in Imperial convoys had an immediate impact, causing the Rebels to reconsider their hyperspace raids after suffering irreplaceable losses in fighters and pilots. They were often used to support larger capital ships, such as Imperial-class Star Destroyers and Rebel Mon Calamari Star Cruisers.
- "They're heading for the medical frigate!"
- ―Wedge Antilles during the Battle of Endor
The Rebel Alliance also acquired a number of these ships through defection, capturing them in battle, or by outright theft. Indeed, one of their first flagships was a Nebulon-B captured in a skirmish over Ylesia, which they christened the Salvation. The Rebels were not the only ones beyond the Empire to acquire Nebulon-B frigates. It was rumored that Kuat Drive Yards would sell the frigates to interested third parties through secret fronts so as not to upset the Imperial Navy. The sale price was 19,400,000 credits, cited as a twentieth of the cost of an Imperial-class Star Destroyer. The Rebels' usage of the Nebulon B was extensive enough that, during the Battle of Oovo IV, Imperial Admiral Hurkk once expressed irritation and pled that the Imperial fleet, if only once, could destroy a Rebel-owned starship that the Imperials did not originally pay for.
The Rebels were able to find other uses for the ships which took advantage of their sophisticated sensors and deep-space multifrequency antennas. Escort frigates were used as long-range scouts, search and rescue ships, or to relay information to command ships during battle. In small, shorthanded, Rebel task forces, Nebulon-B frigates often served as command ships. One Nebulon-B, the Redemption, served the Alliance as their primary hospital ship.
All available Rebel Nebulon-B frigates were deployed at the Battle of Endor, where they took a pivotal part in the battle. The Redemption was lost to the Death Star's superlaser.
The Rebels converted some of their Nebulon-B frigates into medical vessels, which served as mobile hospitals. Weaponry and hangar space was sacrificed to make room for treatment facilities, 15 bacta tanks, 745 beds, and other hospital suites. The crew was slightly modified to include an additional 80 medical personnel and 30 medical droids (such as the 2-1B model). These ships could not carry any fighters, and their armament was reduced to 6 turbolasers (with computer-assisted targeting) and 8 laser cannons. Luke Skywalker was treated for the injuries he suffered on Cloud City onboard the medical frigate Redemption.
Kuat Drive Yards eventually produced an improved version of the Nebulon-B, the Nebulon-B2. They were similar overall, but had higher sublight speed, improved shields and hull armor, a thicker connecting spar, and additional weaponry.
Following the Battle of Endor, Kuat Drive Yards followed up on its successful Nebulon-B design with a new starship class, the 275 meter-long Corona-class frigate. Corona-class frigates were produced solely for the New Republic. Due to the fact that Corona frigates were not part of the New Republic's New Class Modernization Program, orders for the ships remained modest. A number of them served in the Corellian Defense Force during the Second Galactic Civil War.
At least one EF76 was used to make up a secret retreat in 137 ABY. The criminal organization Black Sun used such a frigate around this time, where it was stationed near Vigo Lun Rask's headquarters over Kaer. At least one was used during the Evacuation of Dac.
Behind the scenes
In the Star Wars: The Essential Guide to Vehicles, the entry for the Nebulon-B Frigate is erroneously referred to as a "Rebel Cruiser", which can lead it to be confused with Mon Calamari Star Cruisers. Most sources commonly refer it it as "Nebulon-B Frigate" or "Escort Frigate".
The shape of the Nebulon-B, designed by Nilo Rodis-Jamero, was inspired by an outboard motor.
There is some dispute among fans on the claimed fighter capacity of the Nebulon-B. Computer games and the deck-plans in The Far Orbit Project show a hangar in the forward hull, with a launch aperture in the starboard flank, but there seems to be no such opening on the model used in the movies. Other depictions in the computer games show starfighters docking and launching via an opening in the thin connection between the superstructure and drive bay.
However, the The Rebel Alliance Sourcebook, seemingly the source which first introduced the Nebulon-B's starfighter capability, makes no mention of internal hangars. The text simply says that: "The escort frigate has the capacity to carry up to two squadrons of starfighters into battle. In addition, the ship has docking fixtures to accommodate ships of up to medium freighter size" (p. 60). Since The Empire Strikes Back shows the "docking fixtures" to be external hardpoints on the spar between the prow superstructure and engines, it is possible that the fighters could also be carried on a rack along the spar, in the manner of Carrack-class cruisers, assault frigates, and FarStar.
Additionally, some fans have speculated that some Nebulon-Bs could have been equipped with an enclosed hangar bay fitted under the spar, filling the space between the forward keel and the engine block. Perhaps added as aftermarket additions, such hangars would enable them to carry fighters like X-wings more comfortably, and Kalla's Stanchion, a ship that could belong to this subtype of the class, has appeared in Rebel Alliance hands in an issue of Star Wars: Empire. Although scaling extrapolations when compared with snubfighters shown in the same panels would suggest a size significantly larger than the 300m-long Nebulon-B, the two designs corresponds closely in appearance, and the size discrepancy may simply be a result of artistic license in the comic-book art. Footage from the game Star Wars: The Force Unleashed II depicts the Nebulon frigate Salvation as considerably larger it dwarfs the 65 meter Rogue Shadow by an order of magnitude