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 who pledged their allegiance to the renegade Grand Admiral Demetrius Zaarin and those who remained loyal to the Galactic Empire. As part of an attempted coup against Emperor Palpatine, Zaarin maneuvered his flagship, the Imperial-class Star Destroyer known as the Glory, into the Coruscant system. This action caught the Emperor off guard while he was aboard his personal ship, the Star Destroyer named Majestic. Zaarin successfully disabled the Majestic, then boarded it, capturing Palpatine through the utilization of Force powers wielded by Emperor's Hand Arden Lyn and her apprentices, which were used to overwhelm the Emperor's own abilities.
As Zaarin's escort shuttles made their return trip to the Glory with Palpatine as their prisoner, a flight group consisting of six TIE/D Defenders, led by the Dark Lord of the Sith Darth Vader and Colonel Maarek Stele, materialized from hyperspace. Stele conducted an inspection of the shuttles and proceeded to disable the one carrying the Emperor. Zaarin's response was to deploy TIE Avengers in support, but his efforts proved to be too late. Vice Admiral Thrawn then arrived aboard the Star Destroyer Vanguard along with the corvette Mescue. Personnel from the Mescue boarded the Emperor's shuttle and successfully rescued him, while Stele, Vader, and the remaining TIE Defenders neutralized Zaarin's TIE Avengers. Realizing that his coup had failed, Zaarin subsequently departed from the Coruscant system aboard the Glory.
Not long after the Galactic Empire's triumph over the Rebel Alliance during the Battle of Hoth in 3 ABY, Grand Admiral Demetrius Zaarin, who headed the Empire's research and development for the TIE starfighter series, began formulating a plan to kill Emperor Palpatine and seize control of the Imperial throne. Around this same period, Imperial Admiral Harkov defected to the Rebellion, taking his fleet with him. Consequently, the Empire initiated a campaign to recapture 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 leader of the Black Sun crime syndicate.
With Vader's attention diverted, Zaarin proceeded to finalize his own scheme. While publicly supporting the pursuit of Harkov, the Grand Admiral secretly sought to enlist like-minded individuals from within the Imperial Navy into his personal command. He also enlisted the services of Arden Lyn to act as his operative on Imperial Center, the Empire's capital world. Lyn, an ancient master of the martial art known as teräs käsi and a member of the Emperor's elite group of Force users called the Emperor's Hands, had decided to turn against Palpatine shortly after the Battle of Yavin three years earlier. This decision stemmed from the Emperor's failure 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 remnants of Harkov's fleet had fled to the Ottega system located in the Mid Rim. Vader traveled there aboard the Imperial I-class Star Destroyer Garrett to oversee their destruction. Seeing this as his opportunity, Zaarin began to move his own fleet toward Imperial Center. Simultaneously, the Grand Admiral dispatched several Assassin-class corvettes to the Ottega system, ostensibly to reinforce Vader's forces, but secretly with orders to attack the Garrett upon their arrival. Although the Garrett survived the attack, it sustained significant damage. With the Garrett unable to return to Imperial Center in time to prevent Zaarin's coup, Vader selected Colonel Maarek Stele to lead a group of prototype TIE Defenders on a mission to thwart any potential attack against the Emperor, taking one of the starfighters for himself. Despite encountering an ambush by Zaarin's forces in the Parmel system, the TIE Defender group successfully rendezvoused with the Nebulon-B2 frigate Osprey before proceeding to the Coruscant system.
By bringing his flagship, the Imperial-class Star Destroyer known as the Glory, into the Coruscant system, Zaarin managed to catch the Emperor aboard his private ship, the Imperial I-class Star Destroyer named Majestic. With Lyn's assistance, Zaarin successfully caught Palpatine off guard, and his forces proceeded to disable and board 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, resulting in his capture.
Vader and Stele, along with their TIE Defender group, soon arrived in the system and promptly received a distress signal originating from the Majestic. As they approached the ship, the group detected the launch of six Delta-class JV-7 escort shuttles from the Haven and Hellcat groups, which were carrying troopers from Zaarin's boarding party, as well as the captive Palpatine. Moving to intercept, Vader instructed Stele to identify the shuttle carrying the Emperor. After determining that Palpatine was aboard Haven 3, Stele joined his wingmates in engaging the other shuttles, opting to leave Palpatine's shuttle until it could be disabled without risking harm to the Emperor. Once the other shuttles were destroyed, Stele dispatched his group toward the awaiting Glory while he employed his ion cannons to disable Haven 3.
With Palpatine's shuttle rendered inoperable, the loyal Imperial Assassin-class corvette Mescue arrived in the area to board the vessel and rescue the Emperor. Simultaneously, the severely damaged Majestic managed to escape into hyperspace. As the situation turned against him, Zaarin responded by deploying TIE Avengers in support, but Stele's group moved to engage them. The TIE Defenders eliminated the attacking TIEs, with only Stele and Vader surviving the encounter. Around the same time, Vice Admiral Thrawn arrived aboard the Imperial I-class Star Destroyer Vanguard to assist 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 that his coup had failed, Zaarin fled into hyperspace. Palpatine was then taken to a secure, undisclosed location while Imperial forces formulated plans to pursue Zaarin.
Although the Emperor had been rescued, both Zaarin and Lyn had managed to escape. Stele was rewarded for his role in rescuing the Emperor during a ceremony held at the Imperial Palace, attended by Coruscant's elite. As the Emperor observed from above, Stele was presented with the Emperor's Will medal by Lord Vader. The Emperor maintained a keen interest in Stele, instructing the Secret Order of the Emperor to train Stele in the Force. 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, beginning with an attack on TIE Avenger manufacturing facilities in the Omar system. Thrawn eventually drove him into the Outer Rim Territories and ultimately into the Unknown Regions. Zaarin later launched a second unsuccessful attempt on Palpatine's life, before being ultimately defeated by Thrawn. Thrawn was subsequently promoted to the rank of Grand Admiral, effectively replacing Zaarin within the circle of twelve.
The task of hunting down Lyn was assigned to High Inquisitor Antinnis Tremayne. Following the failure of the coup, Lyn released Thok from her service and began a search for the Kashi Mer talisman, a relic she believed could aid her in her ongoing efforts to resurrect Xendor. She was ultimately killed by Palpatine in 10 ABY.
The battle was included in a chronicle of galactic history by the New Republic Historical Council in 25 ABY, as well as in its updated edition in 36 ABY.
The battle was initially featured 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," which serves as the fifth and final mission of the game's seventh tour of duty, "Treachery at Ottega." In TIE Fighter, the specific shuttle within Haven group that carries the Emperor is randomized. TIE Fighter: The Official Strategy Guide established that Palpatine was canonically aboard Haven 3 within its mission walkthrough, which is 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. This article also elaborated on Stele's fate following the battle.
Abel G. Peña and Daniel Wallace co-authored an article titled "Dirty Dozen: The Imperial Grand Admirals" for Star Wars Gamer magazine. However, after Star Wars Gamer was canceled before the article's publication, Peña and Wallace repurposed much of the information in the Star Wars Insider 66 article titled "Who's Who: Imperial Grand Admirals." The original article contained information about the battle that was ultimately omitted, indicating that Zaarin's timing was partially driven by a desire to strike before Grand Admiral Martio Batch's TIE Phantom project eroded his technological advantage. It also revealed that Lyn was not alone in subduing the Emperor, but was assisted by her pupils. The identities of Lyn's pupils, Thok and 17786, were later confirmed to have assisted her in Peña and Rich Handley's 2013 article titled Barely Tolerable: Alien Henchmen of the Empire.