The confrontation known as the battle of Imperial Center transpired in the vicinity of Imperial Center circa 3.5 ABY. It was a clash between forces loyal to the renegade Grand Admiral Demetrius Zaarin and those who remained loyal to the Galactic Empire. Zaarin initiated a coup against the Emperor Palpatine, bringing his flagship, the Imperial-class Star Destroyer named Glory, to the Coruscant system. This move caught the Emperor by surprise while he was aboard his private ship, the Star Destroyer called Majestic. After disabling the Majestic, Zaarin's forces boarded it and captured Palpatine, utilizing the Force powers of Emperor's Hand Arden Lyn and her apprentices to subdue the Emperor's own abilities.
As escort shuttles under Zaarin's command made their way back to the Glory with Palpatine as a prisoner, a flight group consisting of six TIE/D Defenders emerged from hyperspace. This group was led by Dark Lord of the Sith Darth Vader and Colonel Maarek Stele. Stele examined the shuttles and proceeded to disable the one carrying the Emperor. In response, Zaarin launched TIE Avengers to provide assistance, but it proved to be too late. Vice Admiral Thrawn then arrived aboard the Star Destroyer Vanguard along with the corvette Mescue. The Mescue docked with the Emperor's shuttle and successfully rescued him, while Stele, Vader, and the remaining TIE Defenders eliminated Zaarin's TIE Avengers. Realizing that his coup had failed, Zaarin retreated from the Coruscant system aboard the Glory.
Not long after the Galactic Empire achieved victory against the Rebel Alliance during the Battle of Hoth in 3 ABY, Grand Admiral Demetrius Zaarin, who oversaw the Empire's research and development of the TIE starfighter series, began to plot the death of Emperor Palpatine with the intention of seizing the Imperial throne. Simultaneously, Imperial Admiral Harkov defected to the Rebellion, taking his fleet with him. Consequently, the Empire initiated a campaign to apprehend the rogue admiral, with the Dark Lord of the Sith Darth Vader leading the effort. Vader was also pursuing a personal vendetta against Prince Xizor, the head of the Black Sun crime syndicate.
With Vader occupied, Zaarin finalized his strategies. While outwardly supporting the search for Harkov, the Grand Admiral secretly aimed to attract like-minded individuals from within the Imperial Navy to his own command. He also enlisted the services of Arden Lyn to act as his agent on Imperial Center, the capital world of the Empire. Lyn, a master of the ancient martial art of teräs käsi and a member of the Emperor's elite group of Force users known as the Emperor's Hands, had decided to betray Palpatine shortly after the Battle of Yavin three years prior. This decision came after the Emperor failed to fulfill his promise to resurrect her deceased lover, Xendor.
Immediately following Xizor's death in battle against Vader around 3.5 ABY, the Dark Lord discovered that the remaining forces of Harkov's fleet had escaped to the Ottega system in the Mid Rim. Vader traveled there aboard the Imperial I-class Star Destroyer Garrett to oversee their destruction. Seeing this as an opportune moment, Zaarin began to move his own fleet towards Imperial Center. Simultaneously, the Grand Admiral dispatched several Assassin-class corvettes to the Ottega system, ostensibly to reinforce Vader's forces, but with secret orders to attack the Garrett upon arrival. Although the Garrett survived the assault, it sustained significant damage. With the Garrett unable to return to Imperial Center in time to prevent Zaarin's coup, Vader chose Colonel Maarek Stele to lead a group of prototype TIE Defenders on a mission to thwart any attack on the Emperor, personally piloting one of the starfighters. Despite an ambush by Zaarin's forces in the Parmel system the TIE Defender group managed to rendezvous with the Nebulon-B2 frigate Osprey, before proceeding to the Coruscant system.
Zaarin brought his flagship, the Imperial-class Star Destroyer Glory, to the Coruscant system, where he managed to catch the Emperor off guard while he was aboard his private ship, the Imperial I-class Star Destroyer Majestic. With the help of Lyn, Zaarin surprised Palpatine and his forces successfully disabled and boarded the Star Destroyer. Aided by her students, the Gamorrean Thok and the stormtrooper 17786, Lyn utilized her Force powers to neutralize the Emperor's own abilities, leading to his capture.
Vader and Stele, along with their TIE Defender group, entered the system and quickly received a distress signal from the Majestic. As they approached the ship, the group detected the launch of six Delta-class JV-7 escort shuttles from Haven and Hellcat groups, carrying troopers from Zaarin's boarding party, as well as the captured Palpatine. Moving to intercept, Vader instructed Stele to identify the shuttle carrying the Emperor. Upon confirming that Palpatine was aboard Haven 3, Stele joined his wingmates in engaging the other shuttles, opting to delay action against Palpatine's shuttle until it could be disabled without risking harm to the Emperor. Once the other shuttles were destroyed, Stele directed his group toward the waiting Glory while he used his ion cannons to disable Haven 3.
With Palpatine's shuttle incapacitated, the loyal Imperial Assassin-class corvette Mescue arrived to board the vessel and rescue the Emperor. Around the same time, the critically damaged Majestic managed to escape into hyperspace. As the situation turned against him, Zaarin responded by launching TIE Avengers to provide support, but Stele's group moved to engage them. The TIE Defenders eliminated the attacking TIEs, with only Stele and Vader surviving. Simultaneously, Vice Admiral Thrawn arrived in the Imperial I-class Star Destroyer Vanguard to aid the Imperial forces and began launching TIE bombers to attack the Glory. Approximately ten minutes after Vader's group arrived, Palpatine was safely aboard the Mescue, and Stele joined the TIE bomber attack on the Glory. Realizing his coup had failed, Zaarin fled into hyperspace. Palpatine was taken to a secure location as Imperial forces planned their pursuit of Zaarin.
Although the Emperor was rescued, both Zaarin and Lyn managed to escape. Stele was honored for his role in the Emperor's rescue during a ceremony attended by Coruscant's elite at the Imperial Palace. As the Emperor observed from above, Stele was presented with the Emperor's Will medal by Lord Vader. The Emperor maintained a strong interest in Stele, instructing the Secret Order of the Emperor to train him in the Force, and the pilot eventually became an Emperor's Hand.
Thrawn pursued Zaarin into hyperspace, initiating a long campaign to defeat the rogue Imperial. Zaarin focused on achieving technological superiority with starfighters, first by attacking TIE Avenger manufacturing facilities in the Omar system, before Thrawn drove him to the Outer Rim Territories and ultimately the Unknown Regions. Zaarin later made a second unsuccessful attempt on Palpatine's life before being ultimately defeated by Thrawn. Thrawn was promoted to the rank of Grand Admiral, taking Zaarin's place among the twelve.
The task of hunting Lyn was assigned to High Inquisitor Antinnis Tremayne. Following the failure of the coup, Lyn released Thok from her service and began searching for the Kashi Mer talisman, a relic she believed could aid her in resurrecting Xendor. She was eventually killed by Palpatine in 10 ABY.
The battle was documented in a chronicle of galactic history by the New Republic Historical Council in 25 ABY and its updated edition in 36 ABY.
This battle was initially showcased in the 1994 LucasArts video game Star Wars: TIE Fighter, where players assume the role of Maarek Stele. The battle is depicted in the mission titled "Save the Emperor," the fifth and final mission of the game's seventh tour of duty, "Treachery at Ottega." In TIE Fighter, the identity of the shuttle within Haven group carrying the Emperor is randomized. The official strategy guide for TIE Fighter established that Palpatine was canonically aboard Haven 3 in its mission walkthrough, presented as Stele's after-action report.
Arden Lyn's involvement in the battle was first mentioned in the Star Wars Gamer 5 article titled "The Emperor's Pawns" by Abel G. Peña, Juan Schwartz, and Pablo Hidalgo, which also provided details about Stele's fate after the battle.
Abel G. Peña and Daniel Wallace co-authored an article titled "Dirty Dozen: The Imperial Grand Admirals" for Star Wars Gamer magazine. After the cancellation of Star Wars Gamer before the article's publication, Peña and Wallace repurposed much of the information for the Star Wars Insider 66 article titled "Who's Who: Imperial Grand Admirals." The original article contained details about the battle that were ultimately omitted, indicating that Zaarin's timing was partly motivated by a desire to strike before Grand Admiral Martio Batch's TIE Phantom project diminished his technological advantage, and that Lyn was assisted by her pupils in subduing the Emperor. The involvement of Lyn's pupils, Thok and 17786, was later confirmed in Peña and Rich Handley's 2013 article Barely Tolerable: Alien Henchmen of the Empire.