Although it was only 1,040 meters long (65% of the length of an Imperial-class Star Destroyer), the Nebula-class was built to be a match for an Imperial II. Even with a structure that was a significant departure from the Imperial-class, especially the lack of a command tower, the Nebula was often mistaken for an Imperial design due to its angular lines. Its small size often lead to it being referred to as a "pocket Star Destroyer", much as the later Turbulent-class would be as well.
It was designed to be able to defeat any one enemy Star Destroyer, two heavy cruisers, or an entire line of smaller Imperial support ships. It mounted defenses strong enough to resist even some of the smaller Super Star Destroyers or analog warships.
The armament of the Nebula-class Star Destroyer consisted of 40 heavy turbolaser batteries, 40 turbolaser cannons, 20 ion cannons, 8 tractor beam projectors, and 8 assault concussion missile tubes, each equipped with 30 missiles. Despite the touting of far superior firepower over the Republic-class, the two had nearly similar armaments: the difference was eight concussion missile launchers for the Nebula, and two additional tractor beams for the Republic. The power generation and model of guns was different enough to make the Nebula a far superior design to the Republic. In addition, the hull armor and shield systems of the Nebula outclassed most other ships in the galaxy, including the Republic.
The ships could carry up to sixty starfighters, normally including one assault wing made up of a mixture of K-wing bombers for precision strikes and Defender starfighter for close support. Nebulas could also host a space superiority wing consisting of hyperdrive-equipped E-wings, A-wings, or upgraded X-wings. They also carried 1,600 troops and enough consumables for five to six months, depending on configuration.
Nebula-class Star Destroyers were equipped with a Class 1 hyperdrive for faster than light travel. The design also incorporated a system of lateral thrust vents to increase the ship's maneuverability, giving it far greater agility than most large capital ships.
Development of the Nebula-class Star Destroyer began shortly after the fall of Coruscant. Formally renamed as the Defender when it was made a part of the Defender design program, the Nebula-class refined the core elements of Walex Blissex's Republic-class design into a smaller, more angular hull. The Defender program was derailed by delays caused by political distractions and the campaigns of Grand Admiral Thrawn and the reborn Darth Sidious. When work eventually resumed the design became part of the New Class program and lent its hull design to the Endurance-class carrier. In 15 ABY, the Nebula-class became the last of the eight new starship designs of the New Class to enter service. The ship's introduction was said to be ill-timed, as it occurred during what was considered to be the most peaceful year since the founding of the New Republic.
The first of the class to enter service was the Obi-Wan, named after one of the Rebellion's heroes, Obi-Wan Kenobi. The ship was commanded by Captain Whyrrryk, a female Wookiee. Due to the process of building compact yet powerful warships of this sort, only a small number of Nebula-class ships were built. Only ten were in service c. 17 ABY, with projections of one more being launched each year until the New Class build program was completed. When the Yuuzhan Vong invaded, the few ships of the New Republic's valuable Nebula-class were kept close to the Core Worlds in reserve fleets due to political pressure. Despite this, Nebulas performed well in clashes with the extra-galactic warships once they finally did see combat. Even considering its age, the Nebula-class still represented the peak of modern, efficient Star Destroyer design during the Yuuzhan Vong War.
At least one Defender-class Star Destroyer was still in service by the time of Darth Krayt's Galactic Empire. Pol Temm maintained the ship as part of his The Wheel defense fleet. Attempting to enforce his no-weapons rule, he entered a space battle with a Mandalorian faction called the Mandalorian Supremacists and was reportedly killed when his Defender blew up.
Behind the scenes
Official Expanded Universe information on this ship class has a long and twisted history. Michael P. Kube-McDowell, the author of the Black Fleet Crisis novels, called the Star Destroyer twin for the Endurance-class carrier the "Nebula-class", but the RPG sourcebook Cracken's Threat Dossier named this ship the Defender-class Star Destroyer, and gave it a complicated in-universe history as part of a "Defender" project, along with the Defender-class assault carrier (another "New Class" design created by Kube-McDowell) and the Defender starfighter (an older WEG ship based on a toy from the animated series Star Wars Droids).
The sourcebook also included the only official images (at the time) of the Nebula-class and Endurance-class. Unlike the pictures of the other New Class ships in the book, these two ship classes actually looked like they could have been built on the same spaceframe. This meant that they could not be dismissed as easily as the other pictures of New Class ships, although it was hard to see how the Endurance-class matched the description of Intrepid as "fat-hulled" in Before the Storm.
In a later RPG sourcebook, Starships of the Galaxy, the Defender-class appeared once again, but with slightly changed statistics: the ship's consumables were increased from 5 to 6 months, and it now carried 60 "starfighters and shuttles" rather than the single wing of the earlier resource. The Saga Edition of the same sourcebook would eventually increase the starfighter compliment still further to 60 starfighters and 12 "space transports". Starships of the Galaxy also had a new picture of the Defender, which was sleek, dagger-shaped, and far more similar to other Star Destroyer designs.
The New Essential Chronology added more confusion to the debate by saying that the official name is the Nebula-class Star Destroyer, retconning its name to the scheme originally set down by Michael P. Kube-McDowell.
2011's Invasion: Revelations 3 saw the appearance of a pair of ships specifically called Defender-class, using the appearance from Cracken's Threat Dossier, possibly making the Nebula and Defender into two entirely separate classes of Star Destroyer.
2012's The Essential Guide to Warfare would seek to tie up many of the loose ends regarding the New Class program in a section author Jason Fry jokingly considered calling "continuity hell". It established that the Nebula-class was formally renamed Defender (with no use of "class" or italics) when it was made part of the Defender program. That program stalled and when development on the ship restarted as part of the New Class program several years later it was seemingly back under the original Nebula name.
It is interesting to note that the Nebula-class Star Destroyer and Endurance-class fleet carrier closely mimic the scheme of the Victory-class Star Destroyer and Venator-class Star Destroyer of the Galactic Republic. In both cases, the two destroyers are on the same level of power, but one serves more of a ship-to-ship combat role while the other is more of an escort carrier.
- Before the Storm (First appearance)
- Specter of the Past (Mentioned only)
- Invasion: Revelations 3
- Invasion: Revelations 5
- Cracken's Threat Dossier
- Starships of the Galaxy
- The Essential Chronology
- The New Essential Guide to Vehicles and Vessels
- The New Essential Chronology
- Starships of the Galaxy, Saga Edition
- The Complete Star Wars Encyclopedia
- The Essential Guide to Warfare