The Urch incident represents a conflict that began as a diplomatic mission from the Chiss Ascendancy to the planet Urch. Urch served as the capital of the Urchiv-ki, with whom the Ascendancy maintained a treaty. The Urchiv-ki requested the Ascendancy dispatch Ambassador Boadil'par'gasoi (whose core name was Ilparg) to Urch. The syndics Mitth'urf'ianico "Thurfian" and Irizi'stal'mustro "Zistalmu" selected Admiral Ar'alani's Nightdragon man-of-war Vigilant to provide escort for the ambassador. The Syndics specifically mandated that Senior Captain Mitth'raw'nuruodo "Thrawn" accompany the mission to prevent him from pursuing his investigation of the conquests of the Nikardun Destiny by visiting the Lioaoin Regime. Unbeknownst to the Chiss, the invitation was a ruse, as the Nikardun had already subjugated the Urchiv-ki, who then refused to allow the Chiss to land. Thrawn observed the presence of both a Lioaoin vessel and a Nikardun frigate. As payback for Thrawn's earlier capture of a Nikardun blockade frigate within the Rapacc system, allied Lioaoi, Urchiv, and Nikardun ships attempted to create a trap to capture the Vigilant. However, the Vigilant successfully evaded the Urchiv, Lioaoi, and Nikardun ships, and escaped into hyperspace.
Because of the Lioaoin presence at Urch, Ambassador Ilparg insisted that the Vigilant visit the Lioaoin heartworld to seek an explanation from the Lioaoin Regime. Once the Chiss arrived at the heartworld, the Lioaoi denied any involvement, while a Nikardun Battle Dreadnought approached the Vigilant. Thrawn identified himself to the Lioaoi, which triggered a reaction from several Lioaoin gunboats. From this, he inferred that the Lioaoi were allied with the Nikardun and had specific directives concerning him.
The Urch incident is depicted in the 2020 novel Thrawn Ascendancy: Chaos Rising by Timothy Zahn, which is the first book in Star Wars: The Ascendancy Trilogy.