"Should the Empire abandon theatrics, it could build a thousand small cannons for the cost of a single 'planet-killer.'"
―Haxen Delto, in a report to Airen Cracken[src]

The Onager-class Star Destroyer, nicknamed the Siege Breaker by members of the Rebel Alliance, was a type of rare capital ship and superweapon deployed by the Galactic Empire that was shrouded in secrecy. The Onager-class was considered to be a possibly greater threat than the Death Star, and was seen by the remains of the Empire as a vital instrument to regain power after the Battle of Endor. During the Galactic Civil War, there were several examples of this class. Several ships were the Cataclysm, the Rakehell, the Sunder, and the Onager-class Testbed.


General characteristicsEdit

"I'm just not convinced you need a moon-sized reactor to power a kyber crystal cannon."
―Haxen Delto, to Airen Cracken in a report[src]

The Onager-class Star Destroyer,[1] referred to as the Siege Breaker by the Rebel Alliance,[2] was a type of capital ship[1] and superweapon[3] that was propelled by five engine units in the stern of the starship, three of which were larger than the remaining two.[2] A solar ionization reactor was located in the ventral hull, characterized by its dome shape. The bridge was situated inside the elevated command tower at the center of the ship towards the rear, and the bridge itself was located on a near-trapezoidal structure on top of the command tower.[1]

The front of the ship was defined by two prongs which defined the bow as a T-shaped bow with a long indentation in the center that cut through to almost midship where the primary armament was located. Past the ending of the indentation but before the command tower structure, were two deflector shield generator domes similar to those[1] found in Imperial-class Star Destroyers.[5] The deflector shields, however, were concentrated in the front of the vessel due to the ship's forward firepower being its unique characteristic. As such, the aft and sides of the Onager-class were more exposed.[3] Also in the same fashion as ISDs,[5] the Onager-class had a ridge that traversed the port and starboard sides of the vessel. The Onager-class had two hangar bays, one located on the rear of each of the two prongs that form the T-shape of the bow. The Onager-class was able to receive starships, such as a Lambda-class T-4a shuttle and TIE line starfighters.[1] Members of the Rebel Alliance believed that the Galactic Empire could build thousands of[2] Onager-class Star Destroyers[1] for the price of a single "planet-killer."[2]


"Maybe I lack the Empire's taste for catastrophe?"
―Haxen Delto, to Airen Cracken in a report[src]
Onager firing

The Onager-class Testbed firing its Orbital Bombardment Particle Cannons on a terrestrial body.

Located in the indentation was the primary armament of the Onager-class, which were either two Superheavy Composite Beam Turbolasers that were considered to operate as special battery armaments[1] but had shorter range, or two Orbital Bombardment Particle Cannons.[3] These weapons were speculated to be powered by kyber crystals by members of the Rebel Alliance. The Rebel Alliance believed these kyber crystals were powerful enough to shatter mountains and anything but the strongest energy shield. Because of this, the rebels considered the ship a superweapon.[2]

The foundation of the weapons were at the end of the indentation by the bridge, and each weapon had at least three rings that were separated along the length of the indentation through which the payload of the weapons passed through. When these armaments fired, the indentation and rings glowed red, and could fire almost simultaneously. These two superheavy composite beam turbolasers were considered some of the Galactic Empire's most devastating weaponry and could be used to perform ignition attacks from beyond long range, allowing it to keep the crew of the vessel safe. In concert with these two primary weapons, the Onager-class was also equipped with massive particle cannons.[1] These weapons in the indentation of the vessel were longer than half of the ship. The Onager-class was also equipped with a number of laser cannons throughout its hull ridges.[3]



An Onager-class Star Destroyer escorted by an Imperial-class Star Destroyer.

The Onager-class Star Destroyer was shrouded in secrecy,[3] and were used by the Galactic Empire as a specialized orbital bombardment platform.[1] The Rebel Alliance believed that the Siege Breaker, if their intelligence was correct, acted in the capacity of a portable cannon.[2] The deployment of Onager-class Star Destroyers in more sensitive Imperial operations had the characteristic of not being able to be confirmed or denied,[1] and was unlike the common Victory-class and Imperial-class Star Destroyers. Since the Onager-class could destroy a base from orbit or punch through a cruiser, it was considered to be a valuable addition to fleets. Although the Death Star was one of the most visible symbols of the Empire's power, it was not their only superweapon, as the Onager-class was hidden in secrecy and may have been considered as an even greater threat.[3]


Early historyEdit

"Passing on the latest from Maj. Harinar and Col. Delto. I've allowed their teams to operate independently, theorizing on the most likely configuration that a kyber superweapon would take. As you will see, they arrived at very different conclusions."
―Airen Cracken in a report to Mon Mothma[src]
Siege breaker

An Onager-class Star Destroyer as illustrated in The Rebel Files

Sometime between the years[2] 5 BBY and 0 BBY[6] during the early rebellion against the Galactic Empire, after the Rebel Alliance began detecting hints of a kyber crystal-powered superweapon, Rebel Chief of Intelligence General Airen Cracken allowed Rebel Alliance Intelligence Service Major Capin Harinar of the Technology division and Colonel Haxen Delto of the Communications division to operate independently and theorize based on leads on the most likely configuration such a superweapon could take, and both arrived on different conclusions.[2]

Major Harinar gave a report to General Cracken on an Imperial project named Operation: Cinder. Colonel Delto, however, reported to Cracken on what was known as a Siege Breaker. His analysis led him to believe that the Empire could build thousands of relatively smaller cannons, which the Rebel Alliance dubbed Siege Breakers, for the cost of a single "planet-killer." The document also included possible speculation on the characteristics and armament of the Siege Breaker, an illustration of a Siege Breaker, and a comparison to a Jedi lightsaber as they both could cut through almost any material while remaining stable in a satchel.

Delto used the document to pursue the principle that the Siege Breaker was more likely than the a large "planet-killing" battle station. After receiving both reports by Harinar and Delto, Cracken included them in his own report to Alliance Chancellor and Commander-in-Chief Mon Mothma. The report was later included in The Rebel Files, a central data repository that contained sensitive non-electric documents. Eventually, it was discovered that the "planet-killer" was the Death Star, a battle station that had the ability to destroy entire worlds.[2]

Galactic Civil WarEdit


The Onager-class Star Destroyer Cataclysm was stationed near a pair of gravity wells at one point.

It was later discovered that the information gathered by Alliance Intelligence on Operation: Cinder[7] and the Siege Breaker[2] was correct,[7][2] including the illustration of the Siege Breaker[1] and of the Operation: Cinder satellites.[7] The Siege Breaker[2] was officially designated as the Onager-class Star Destroyer and was deployed by the Imperial Navy to various sensitive operations.[1]

Although a relative rarity, there were several examples of the Onager-class, with four being the Rakehell, the Cataclysm, the Sunder, and the Onager-class Testbed. Even during the Galactic Civil War, the Onager-class Star Destroyer was still being refined, and the Testbed allowed for the deployment of the Onager-class in its experimental variant.[3] The Rakehell at one point was accompanied by two Victory-class Star Destroyers while the Cataclysm was stationed near a pair of gravity wells and was receiving a Lambda-class T-4a shuttle and two TIE line starfighters.[1] The Sunder at one point participated in a battle against a Rebel Alliance MC80 Star Cruiser inside an asteroid field and sustained major damage. The Onager-class Testbed at one point fired its primary armament on a terrestrial body.[3]

The Onager-class Star Destroyer remained active after the decisive Battle of Endor that resulted in the destruction of the second Death Star and the death of Imperial Emperor Palpatine, and was still considered to be new and technologically advanced.[1] Despite the Rebel victory at Endor, the Onager-class endured in secrecy.[3] Imperial forces that survived the Battle of Endor made strides to strengthen their grip on the galaxy and launch a counter strike against the Rebel Alliance. The remains of the Empire believed that the Onager-class Star Destroyer was critical to achieving victory in the final stages of the Galactic Civil War.[1]


"Perhaps this is what the First Order is up to? Would represent a more containable risk."
―Caluan Ematt in a written annotation on The Rebel Files[src]

In 34 ABY[8] after the fall of the Galactic Empire, The Rebel Files were uncovered during an excavation on Durkteel and eventually reached the Resistance, a private military with roots to the Rebel Alliance and supported by some members of the New Republic. At that time, the Resistance was locked in a cold war with the First Order, the successor government of the Galactic Empire. Resistance Major Caluan Ematt reviewed the documentation related to the[2] Onager-class Star Destroyer[1] and left a written annotation describing that he believed that the First Order may have used technology or inspiration from the[2] Onager-class Star Destroyer,[1] and would represent a more containable risk.[2] After war erupted between the First Order and the Resistance, the First Order Navy deployed the Mandator IV-class Siege Dreadnought, which functioned and was armed in a similar capacity[9] to the Onager-class.[1]

Behind the scenesEdit

The Onager-class Star Destroyer[1] was first mentioned and pictured in the canon boxset and reference book Star Wars: The Rebel Files as the Siege Breaker. The book was authored by Daniel Wallace, had illustrations by Joe Corroney[2] and was originally released in November 21, 2017.[10] It was first identified as the Onager-class Star Destroyer in a news article by Fantasy Flight Games on its upcoming Star Wars: Armada expansion packs, Onager-class Star Destroyer Expansion Pack and Nadiri Starhawk Expansion Pack, to be released in 2019.[1]

Lucasfilm Story Group executive Leland Chee confirmed that in developing the Onager-class for Star Wars: Armada, the design came first.[11] When asked how the design for the Onager-class came to be, Chee stated that the Onager-class was designed for The Rebel Files. When Fantasy Flight Games saw the design, it was further developed for their product as the design was appealing and fulfilled a gameplay need.[12]


Wookieepedia has 8 images related to Onager-class Star Destroyer.

Notes and referencesEdit

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 FFG A New Age of Battle on Fantasy Flight Games' official website (backup link)
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 Star Wars: The Rebel Files
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 FFG The Siege Breaker on Fantasy Flight Games' official website (backup link)
  4. Star Wars: The Rebel Files establishes that 14 AFE and 19 AFE in the Imperial calendar are respectively 14 and 19 years after the Proclamation of the New Order. Given that Star Wars: Galactic Atlas dates the Proclamation to 19 BBY, 14 AFE must therefore correspond to 5 BBY, while 19 AFE corresponds to 0 BBY. The content of Star Wars: The Rebel Files is chronological, and the information pertaining to the Onager-class Star Destroyer corresponds to the time between 5 BBY and 0 BBY. As such, the Onager-class must have been introduced during or prior to 0 BBY.
  5. 5.0 5.1 Rogue One: A Star Wars Story
  6. Star Wars: The Rebel Files establishes that 14 AFE and 19 AFE in the Imperial calendar are respectively 14 and 19 years after the Proclamation of the New Order. Given that Star Wars: Galactic Atlas dates the Proclamation to 19 BBY, 14 AFE must therefore correspond to 5 BBY, while 19 AFE corresponds to 0 BBY.
  7. 7.0 7.1 7.2 Star Wars Battlefront II
  8. Star Wars: The Rebel Files establishes that The Rebel Files were buried on the same day as the Battle of Endor, which takes place in 4 ABY, according to Star Wars: Galactic Atlas. Since Star Wars: The Rebel Files also establishes that the files were rediscovered thirty years later, they must have been uncovered in 34 ABY.
  9. Star Wars: Episode VIII The Last Jedi
  10. Canfield, David (2017-11-21, 5:00 pm). Star Wars: The Rebel Files book trailer unlocks secrets of the Rebel Alliance. Entertainment Weekly. Meredith Corporation. Archived from the original on July 25, 2018. Retrieved on July 29, 2018.
  11. TwitterLogo Leland Chee (@HolocronKeeper) on Twitter "It's been quite a long time coming but at last we reveal the look of the Nadiri Starhawk introduced in the Aftermath books. With the Onager, the design came first." (backup link) (screenshot)
  12. TwitterLogo Leland Chee (@HolocronKeeper) on Twitter "Rebel Files came first. FFG liked the design and it fulfilled a gameplay need." (backup link) (screenshot)

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