The decisive confrontation in the Chiss Ascendancy's involvement during the conquests of the Nikardun Destiny was the conflict above Primea. Senior Captain Mitth'raw'nuruodo of the Ascendancy masterminded this engagement, which unfolded in the space surrounding Primea, the homeworld of the Vak. Thrawn cleverly outmaneuvered General Yiv and his Nikardun forces throughout the battle, skillfully turning the Vak Combine, whom Yiv sought to subjugate, against their would-be conquerors. The battle concluded with Thrawn's capture of Yiv, who then became a prisoner held by the Ascendancy.
Prior to this pivotal battle, the Chiss and Nikardun forces, along with factions under Nikardun control, engaged in a series of skirmishes. Thrawn dispatched the caregiver Mitth'ali'astov and the sky-walker Che'ri with a message for the Vak leadership, returning a Vak fighter that Thrawn had previously commandeered during an escape from Primea. Vak forces loyal to the Nikardun plotted to capture the two Chiss but instead delivered a fabricated message, both of which Thrawn anticipated. Yiv issued a demand to the Ascendancy, threatening that Thrawn provide a ransom for the problems he had caused. The Chiss Syndicure of the Ascendancy determined that the capture of a sky-walker necessitated a military response. Accompanied by the Pathfinder navigator Qilori, Thrawn journeyed to Yiv's location aboard an unarmed freighter. Qilori, previously aligned with Yiv, altered the arrival coordinates, diverting the freighter from its intended destination above Primea to a more distant point within the system.
As Yiv confronted Thrawn with four Nikardun Battle Dreadnoughts, including the flagship Deathless, five Chiss warships under the command of Admiral Ar'alani arrived at Primea. They provided the Vaks with intelligence regarding the positions of Nikardun vessels in orbit, fulfilling Thrawn's offer in his earlier message. The Vaks authorized Ar'alani to engage the Nikardun forces. Yiv dispatched his three dreadnought escorts to reinforce his blockade of Primea. The Springhawk sustained damage and went silent, prompting Admiral Ar'alani to request humanitarian assistance from nearby Vak patrol boats. The Vak complied, but the Nikardun vessels targeted and destroyed the patrol ships, inciting the Vak Combine to turn against the Nikardun. Yiv attempted to ensnare Thrawn's freighter with a tractor beam, but Thalias and Che'ri released tava mist into the bridge of the Deathless, enabling Thrawn to break free. Instead, he crashed his freighter into the viewport, protected by a Galactic Republic energy shield acquired from Mokivj. Thrawn then boarded the bridge, rescued the two Chiss prisoners, and successfully captured Yiv. With Yiv's capture, the Nikardun Destiny lacked a capable leader, leading to the collapse of their expansionist ambitions.
Following Yiv's defeat and capture on Primea, the Chiss Expansionary Defense Fleet launched the Nikardun campaigns to eliminate the threat posed by the remaining elements of the Nikardun military.
The battle that occurred over Primea was the climactic event of the 2020 novel Thrawn Ascendancy: Chaos Rising written by Timothy Zahn.