The Battle of To-phalion Base involved an offensive operation orchestrated by Grand Admiral Zaarin. His target was Grand Admiral Thrawn, and his objective was the theft of the Vorknkx Project.
The purpose of the project was the development of technology capable of making a freighter invisible. The Corellian Corvette Vorknkx served as the testing platform. Zaarin, formerly an Imperial Grand Admiral, had prior knowledge of the project from his time overseeing new technology development for the Empire. Soon after his act of treason, Zaarin and his accomplices resolved to seize the cloaking technology undergoing trials within the Vorknkx Project. His military units launched an assault on the research facility, compelling the personnel to relocate the project to a more secure site. The new project laboratory was established within To-phalion Base, an asteroid that had been excavated by the Empire. The asteroid base was defended by surrounding asteroids equipped with concealed turrets. The precise location of this base remained confidential; however, Zaarin successfully infiltrated several spies into the base. Once the spies disclosed the base's vulnerabilities, Zaarin dispatched an assault force comprising sixteen Muurian transports accompanied by TIE Defenders, a fighter program that Zaarin had overseen during his tenure as a loyal Imperial admiral.
Imperial Grand Admiral Thrawn, still loyal to the Empire, deployed a squadron of TIE Avenger fighters to reinforce To-phalion base. Maarek Stele, Thrawn's most skilled pilot, commanded the squadron. The TIE Avenger squadron, in conjunction with To-phalion Base's asteroid-based turret defenses, successfully repelled the Muurian Transports. However, as the initial clash neared its end, To-phalion base's asteroid turret defenses were rendered inoperable. A shuttle, identified as Lambda 3, initiated an unsanctioned launch from To-phalion Base's hangar. The pilot was identified as one of Zaarin's infiltrators. Maarek Stele, acting under orders, destroyed the shuttle. Stele and the remaining members of the squadron returned to To-phalion Base's hangar.
Following the sabotage perpetrated by Zaarin's spy, which disabled the base's turrets, Grand Admiral Thrawn planned to arrive aboard the Nebulon-B frigate Maru Ki, bringing reinforcements. Thrawn hoped that Zaarin himself would appear, allowing him to capture or eliminate the traitor. Before Thrawn's arrival, Zaarin launched a second wave of attackers, consisting of 4 Assassin-class corvettes from group Rok, a group of assault transports, and a squadron of Assault Gunboats. With To-phalion Base's turret defenses still offline, Stele's squadron was deployed to defend the base. Eventually, Thrawn arrived on the Maru Ki, and Zaarin's forces were forced to retreat. Unfortunately, the traitors had managed to destroy all the asteroid turrets protecting To-phalion Base's main asteroid base.
Zaarin initiated a final, desperate attack to either capture or destroy the Vorknkx Project. He arrived aboard his flagship, the Star Destroyer Glory. The ship launched successive waves of TIE/LN starfighters, interceptors, bombers, and TIE Defenders. Grand Admiral Thrawn summoned his task force to encircle Zaarin. However, before his task force arrived, Zaarin's ships inflicted severe damage on the frigate Maru Ki. While initiating a jump to hyperspace, Thrawn and his crew evacuated the ship via shuttles. Subsequently, the traitor's Star Destroyer targeted To-phalion Base, disabling its shields. The base personnel launched Corvette Vorknkx in an attempt to secure it, but the remaining Zaarin's spies were on board, and they piloted it directly into the hangar of Glory, with the experimental cloaking device activated. Shortly after these events, Thrawn's task force arrived. It was composed of the Star Destroyer Grey Wolf, the Interdictor Cruiser Corvus, and the Strike Cruisers Ebolo and Daring. Corvus experienced a delay, and without the cruiser's gravity well generators to impede the hyperdrive engine on the Glory, Zaarin and his forces escaped with the Corvette Vorknkx, and its cloaking device.