A disagreement between the Galactic Empire and the Grysk Hegemony, situated within the Unknown Regions, unfolded sometime after the Battle of Atollon. The beginning was marked by Emperor Palpatine detecting a significant disturbance in the Force at the edge of the galaxy. He dispatched his most valuable assets: Darth Vader together with Grand Admiral Thrawn. Following the discovery that Grysk forces had infiltrated Imperial territory, the military of the Chiss Ascendancy became involved.
The Imperial capital ship known as the Chimaera made its way to Batuu with the purpose of discovering the origin and implications of a disturbance in the Force, as perceived by Emperor Palpatine. While the Chimaera was positioned above Batuu, Sensor officer Commander Hammerly identified four small transports arranged loosely above the planet. These, in combination with the six starships already present on Batuu's surface, brought the total to ten. Commodore Karyn Faro engaged in conversation with Hammerly as the crew of the Chimaera worked to gather as much data as possible about the ships, concluding that they could be either small freighters or compact warships. As the information gathering progressed, two more ships materialized from hyperspace directly ahead of the Chimaera at a distance of 400,000 kilometers. Hammerly determined that these ships were, at a minimum, a type of long-range heavy freighter, heading directly for Batuu. Faro surmised that each of the unidentified ships were en route to Black Spire Outpost, where Grand Admiral Thrawn and Darth Vader were conducting their investigation.
Hammerly discovered that the two newly arrived starships had emerged from the same hyperlane that the Chimaera had used, approaching from over the Chimaera's rear. Shortly before a skirmish on Batuu occurred between Thrawn and Vader against a group of Darshi, one of the heavy freighters was advancing towards Thrawn and Vader's location, while the remaining ships maintained their orbital positions above Batuu. Vader instructed Commander Kimmund and his unit to intercept, assess, and engage the other heavy freighter.
Not long after the skirmish concluded, Kimmund and his stormtroopers moved towards the heavy freighter aboard the Darkhawk. The Grysk vessel detected the Darkhawk and broke orbit. Defender Squadron One then arrived, preventing its escape by disabling the starship, and subsequently drove off the other smaller transports.
Kimmund successfully apprehended several Grysk warriors, whom Thrawn directed him to bring aboard the Chimaera for examination. Later, Kimmund and his legion were aboard the Darkhawk, when several Grysk prisoners broke free and proceeded to board the Darkhawk. With communication cut off and troop numbers dwindling, Kimmund anticipated his impending death. Fortunately for Kimmund, Thrawn's Noghri assassin, Rukh, was present. Using Rukh's cloaking device as a tactical advantage, Kimmund and Rukh managed to overcome the retreating Grysks.
The Imperial–Grysk disagreement acted as the primary Imperial Era storyline for the 2018 novel titled Thrawn: Alliances (with half of its events taking place near the conclusion of the Clone Wars). Aspects of the disagreement extended into the novel's 2019 sequel, Thrawn: Treason.