The clash known as the Sunrise incident unfolded within the Sunrise system during 18 BBY. It involved the forces of the Chiss Ascendancy, specifically the Chiss heavy cruiser Springhawk commanded by the Chiss Senior Captain Mitth'raw'nuruodo, also known as "Thrawn." They faced off against the Nikardun blockade frigate Aelos, seized by the Paccosh and crewed by Paccian commandos. Additionally, a Grysk vessel belonging to the warlike Grysk species was present, stationed alongside the Kilji picket cruiser Hammer from the Kilji nation within the Illumine.
Following the attack on Rapacc by the Hammer and General Crofyp's Kilji war cruiser Anvil, where the Springhawk's arrival resulted in the destruction of the Anvil and the death of its commanding officer, the Hammer escaped. As per instructions from General Crofyp and Jixtus, it headed to the Sunrise system. The warship then took up position alongside one of Jixtus's warships. Shortly after, the Nikardun blockade frigate Aelos arrived, requesting permission from the Grysk vessel to dock with the Hammer. This permission was granted via comm by a Grysk individual. After docking, the blockade frigate crew boarded the Kilji warship and killed everyone aboard, including the ship's commander, Colonel Tildnis.
The Springhawk had entered the star system to capture Thrawn, who was on the Aelos. The Grysk warship then opened fire on the Chiss vessel. However, after Thrawn obtained data regarding the Illumine Kilhorde, the Kiljis' battle fleet, the Grysk ship was forced to redirect its laser fire towards the Hammer. Shortly after, the surviving individuals—the Hammer's navigator Sarsh, Thrawn, Paccosh Commander Uingali foar Marocsaa, and his Paccian commandos—fled the Hammer aboard the Aelos. "Bogey One," the Springhawk's codename for the Grysk vessel, destroyed the Hammer and jumped to hyperspace, issuing a warning from Thrawn not to return.
At some point in time, the Grysk operative known as "Jixtus" formed an alliance with Generalirius Nakirre, the leader of the Kilji species' nation, the Kilji Illumine. This alliance meant that the Kilji received military advice from the Grysk, directing the conquests of enlightenment towards the most vulnerable peoples and worlds. In return, Nakirre provided Jixtus with transport aboard the war cruiser Whetstone across the Unknown Regions. In 18 BBY, Jixtus dispatched Illumine General Crofyp's task force to the Rapacc system, where the Kilji force encountered the Paccosh-commandeered Nikardun blockade frigate Aelos. The Aelos, with assistance from the Chiss heavy cruiser Springhawk, attacked Crofyp's war cruiser Anvil. The Anvil was destroyed, and Crofyp was killed. Consequently, the remaining warship from the task force—the Kilji picket cruiser Hammer—retreated to the Sunrise system and established a position with a Grysk vessel above the planet Sunrise.
Chiss Senior Captain Mitth'raw'nuruodo, the commander of the Springhawk who was aboard the Aelos, discovered a Kilji escape pod that had managed to escape the destruction of the Anvil, and subsequently recovered it. Upon finding the Pathfinder navigator Qilori inside, Thrawn instructed him to use his abilities—which, unbeknownst to both Thrawn and Qilori, were derived from the Force—to locate the Hammer's Pathfinder. Despite the Navigators' Guild's prohibition against such actions, Qilori complied and successfully tracked Pathfinder Sarsh to Sunrise, where the Aelos encountered the Grysk and Kilji forces.
Paccosh Commander Uingali foar Marocsaa, the commander of the Aelos, requested urgent assistance from the Hammer and its ally. A Grysk granted this request, instructing the blockade frigate to position itself on the portside of the picket cruiser Hammer. Meanwhile, the Springhawk arrived, declaring the Paccosh as their prey while engaging the Grysk vessel, codenamed Bogey One and commanded by Mid Captain Ufsa'mak'ro "Samakro". However, the Chiss heavy cruiser was unable to inflict any damage on Bogey One, as the Grysks employed missiles screened by dibbers, preventing their destruction and disrupting laserfire. Having reached the Hammer's side, Uingali ordered his crew to deploy a Crippler net against the Kilji cruiser's weapon cluster, which included the tractor beam that was guiding them to the midships docking port, effectively disabling it. The Aelos then docked with the Hammer, and the Kiljis aboard approached the vestibule individually, rather than in organized fire teams. This allowed Thrawn and the Paccian commandos brought by Uingali to easily eliminate them. Guided by Qilori, the Paccosh and the alien pair proceeded to the bridge, where a Paccian commando killed three groups of Kiljis and Colonel Tildnis, the starship's commander.
Due to the Kiljis' design of their ships for use by their inefficient servants, the Paccosh were able to quickly learn the controls of the picket cruiser. They then fired upon Bogey One. Sarsh, who was present on the bridge, provided Thrawn with a Kilji data rectangle containing information on the Illumine Kilhorde, the Kiljis' battle fleet, including its design, combat doctrines, and vulnerabilities. With Thrawn having acquired all the information he needed from the Hammer, he instructed the Paccian commandos to have the Hammer fire all its weapons at Bogey One while they escaped aboard the Aelos. Although the Springhawk had been unable to damage the Grysk vessel, the Kilji weapons proved effective, as the Grysks did not anticipate being targeted from behind. Consequently, the Grysks destroyed the Hammer as they fled into hyperspace.
The incident was followed by the Paccian slaughter, during which Paccian commandos killed most of the Grysk enslavers remaining on Sunrise. After the slaughter—and a follow-up battle against the remaining enslavers—the Grysk vessel that fled Sunrise reported to Jixtus. Jixtus also received a report from Qilori, who had encountered two Grysks on Sunrise. These Grysks informed him that upon receiving "the signal" from Jixtus, they would bring the operative "the one."
The data on the Kilhorde obtained from the Hammer was given to the Paataatus government of the Hiveborn. They then deployed a Paataatus attack fleet to destroy the Kilji battle fleet. The destruction of the Illumine fleet subsequently led Jixtus to kill Nakirre.
The Sunrise incident is depicted in the 2021 novel Thrawn Ascendancy: Lesser Evil, which serves as the concluding book in Timothy Zahn's Star Wars: The Ascendancy Trilogy.