The Zaarin splinter government was a regime created by the ex-Grand Admiral Demetrius Zaarin in his attempt to overthrow Emperor Palpatine and take over the Galactic Empire. Though Zaarin was in good light of the Emperor, he was dissatisfied with Palpatine's rule, and decided to put himself on the throne. Zaarin recruited Arden Lyn, a dissatisfied Dark Jedi. He also attempted to recruit ace TIE pilot Maarek Stele, but failed. The splinter government's first action was an attack above Coruscant against Palpatine's personal Star Destroyer, the Majestic. The attack failed, though, as Darth Vader, Stele, and five other pilots saved the Emperor and defeated his forces there. Zaarin's regime then escaped to the Outer Rim Territories, where they continued a campaign against the Empire until he was killed shortly before the Battle of Endor, in 3 ABY.
In 3 ABY, during the pursuit of the rogue Admiral Harkov, Grand Admiral Demetrius Zaarin set forth his plans to overthrow Emperor Palpatine in an attempt to assume control of the Galactic Empire. While the Imperials were preoccupied with putting down Harkov's pro-Rebel Alliance forces, Zaarin mustered his own personal army in preparation for his takeover of the Empire. Utilizing his vast resources and various advanced technologies, Zaarin was in position to overthrow the Emperor in what he expected to be a swift and complete campaign.
Some time later, Admiral Harkov was captured and subsequently executed by Darth Vader on charges of treachery, and the Imperial loyalists had tracked down his surviving fleet to the Ottega system, where they were aligned with a contingent of Rebel forces. Finding themselves outmatched, the Imperials called on Zaarin and his forces to assist in routing Harkov's fleet. This was where Zaarin would launch his coup d'état. Zaarin's forces arrived on the scene as ordered, but instead of helping the Imperials, they attacked the Imperial Star Destroyer Garrett, Vader's flagship. Although the loyalist forces succeeded in driving them off as well as exterminating Harkov's allies for good, the Galactic Empire was weakened, so the Imperial forces loyal to the Emperor raced to Coruscant to put an end to the impending coup.
Zaarin later captured and boarded the Emperor's personal flagship, the Majestic. With Palpatine captured, Zaarin ordered his strike team to deliver the Emperor to him personally on his flagship, Glory. However, he was thwarted when loyal Imperial forces, led by Darth Vader and Vice Admiral Thrawn, arrived and rescued the Emperor. With the failure of the coup, Zaarin and his task force fled to the Outer Rim Territories.
The failure to overthrow Emperor Palpatine was a severe setback for Zaarin's splinter government, but Zaarin himself remained active. Operating from the Glory and those bases which remained in Zaarin's control, his insurrectionist forces launched a campaign of terror and sabotage against the Empire. The first step in Zaarin's plan was to strip the Empire with the advanced technologies of his creation that they still possessed, providing him with the technological advantage. He started his campaign by destroying the TIE/Advanced starfighter Deep Space Manufacturing Facilities of Omar. Although he suffered severe losses, Zaarin and his forces were ultimately successful in destroying all TIE/Advanced facilities in the Omar system, dealing a major blow to the Empire. Zaarin continued his campaign by assaulting the Imperial space station Research, a facility previously under Zaarin's direct command. By destroying the facility, Zaarin hoped to deny the Empire access to the newly-commissioned TIE/D Defender, which was still being developed. Once again, Zaarin achieved victory over the Empire by destroying Research, but the surviving TIE Defender prototypes were safely transferred to Coruscant prior to the base's destruction.
This setback however, did not stymie Zaarin's war of attrition against the Empire, as he continued to raid Imperial facilities of valuable technologies and would continue to deny the Empire access to them. In the battle for control of the TIE Defender technology, Zaarin schemed with numerous pirate groups in the Outer Rim Territories to acquire control of the resources and personnel needed to further the development and manufacture of the TIE Defender. One of the consequences of this was the acquisition of the fighter craft by the Nami, a warrior race aligned with the Rebel Alliance. However, this brief but destructive crisis was resolved by loyal Imperial forces before the technology fell into Rebel hands. However, Zaarin still possessed this technological advantage.
The growing threat posed by Admiral Zaarin eventually prompted Emperor Palpatine to promote Vice Admiral Thrawn to the rank of Grand Admiral, filling the vacancy left by Zaarin in the Emperor's inner circle. The Emperor personally charged Thrawn with the destruction of Zaarin and his treacherous fleet. Thrawn's strategy would be to deny Zaarin of his technological advantage through the top-secret development of a heavy starfighter capable of countering the threat posed by Zaarin's fleet of TIE Defenders. This starfighter, the Missile Boat, would spearhead Thrawn's campaign to destroy Zaarin's armada.
Admirals Zaarin and Thrawn sparred in the Semag system in the Unknown Regions where Thrawn intended to strip Zaarin of the bulk of his starfleet before a second attempt on the Emperor's life could be staged. Although Thrawn's campaign proved devastating and many forces loyal to Zaarin had been eliminated, losses for both sides were heavy as Zaarin's forces had managed to inflict enormous losses on the advance fleet Thrawn had deployed against the enemy. To lure Zaarin out into the open, Thrawn laid several traps in an effort to bait Zaarin into pursuing top-secret Imperial technologies such as the newly-deployed Missile Boat. Zaarin launched several efforts to gain possession of these and other technologies, but his forces were swiftly routed by Tan Maarek Stele, who flew the Missile Boat with great distinction. However, despite these losses Zaarin was not deceived by the Grand Admiral's ploys and ultimately retreated deeper into the Unknown Regions before Thrawn's forces could confront him directly. Admiral Zaarin was not swayed by the losses he endured however and after successfully acquiring a full squadron of Missile Boats from an Imperial convoy focused his energies on the capture of the Empire's next top-secret project: A cloaking device being tested aboard the modified CR90 corvette Vorknkx. In order to ensure shortly after his theft of the Missile Boats that the Imperials could not develop any more Missile Boats, Zaarin's faction also had the factories developing them destroyed in an planetary bombardment, killing thousands. This, as well as an unrelated theft of one of the Missile Boat prototypes, the Sealion, by the Rebel Alliance, led to the Emperor ordering for any and all surviving Missile Boats still in Imperial custody placed into lockdown and put in a secure location until further notice shortly before Zaarin's final stand.
However, Zaarin was eventually defeated by Thrawn in the Emperor's Will campaign, and killed, after Thrawn exploited Zaarin's dependence on advanced technology by letting Zaarin escape with the Vorknkx while cloaked, knowing full well that the ship had a critical flaw within its cloaking device would have the ship be utterly destroyed once it entered hyperspace, thus ending his coup.
The government was comprised of a military junta. As such, its governing process was based strictly on a militaristic fashion and it was ruled by a number of officers. They included Zaarin himself and Commander Raveen. What remained of his government was disbanded after his death, and the deaths of his officers during the final stages of the insurrection.
Zaarin had a fleet of Star Destroyers and other smaller vessels, as well as several stormtrooper units. Being a former TIE fighter researcher, Zaarin's forces used experimental models that were largely unavailable to loyalist Imperial pilots. He was also occasionally aided by forces of the Alliance Fleet. Despite the technological advantage, they were ultimately defeated. All starfighter squadrons, as well as most shuttle and transport craft, were given a "Z-" designation in front of their names when described by loyal Imperial forces, largely for ease of identification during battle. In addition, unlike the mainline Imperial forces, Zaarin's TIE squadrons were modified to come equipped with shield generators.
Their vessels included Assassin-class corvettes, including at least three groups known as the Arditi group, BaKaar group, and Falcon group; Gamma-class ATR-6 assault transports and the Oz, Ram and Divine Wind, including the Upsilon group, Z-Epsilon group, Z-Lambda group, Z-Omega group, and Z-Sigma group as well as the Elpi, the Immobilizer 418 cruisers Harpago and Grappler, Alpha-class Xg-1 Star Wing squadrons including the Mu (later Z-Mu), Z-Nu and Tau (later Z-Tau) Squadrons, and TIE/sa bomber squadrons including the Z-Alpha, Z-Beta, Z-Delta, Z-Eta, Z-Gamma, and Z-Theta Squadrons, TIE/ad starfighters including Alpha Squadron and Z-Zeta, Delta-class JV-7 escort shuttles including the Hellcat and Haven groups, Imperial-class Star Destroyers such as the Glory, Nebulon-B2 frigates including the Raptor and Shadow, TIE/LN starfighters including Z-Delta and Z-Theta squadrons, at least 2 Modular conveyors which included the Cod, YT-1300 light freighters such as the Coral, at least three CR90 corvettes including the Caplure and Vorknkx, Carrack-class light cruisers including the Jumimi, Strike-class medium cruisers including the Serpent, TIE/IN interceptors including the Z-Delta Squadron, TIE/D Defenders including the Delta, Iota, and Theta Squadrons, Assault Gunboats, Muurian transports including the 500 2, assault transports, Lambda-class T-4a shuttles including the Sigma group, Beta-class ETR-3 escort transports including the Lambda 1, and others.
Besides the standard military, he also had Force-sensitives led by former Emperor's Hand Arden Lyn, who were personally responsible for capturing the Emperor by using their combined Force abilities to neutralize the Sith Lord.