The skirmish above Solitair was a conflict of the Lioaoin pirate campaign above the planet Solitair, homeworld of the Garwian species and capital of the Garwian Unity, several years before the defeat of the Nikardun Destiny in 19 BBY. The Lioaoin Regime intended to negotiate terms of surrender to end a war with the Garwians, but the Ruleri presented the events to visiting Chiss officials as an attack on the Garwian homeworld. A general of the Garwian military begged the Chiss officers present for tactical advice to defeat the "invaders", which he intended to use to attack and conquer parts of Lioaoin space.
Initially, Senior Commander Thrawn provided tactical analysis of the Lioaoins' weaknesses, but he was cut off by Commodore Ar'alani, who insisted on remaining neutral. Ar'alani attempted to contact the Destrama to extract the two Chiss, but discovered they were being jammed. After Thrawn insisted the Garwians lift the jamming, they discovered that the Lioaoins had come to negotiate terms of surrender to the Garwian Unity. Angry at being manipulated to bend Chiss law, Ar'alani and Thrawn departed with a threat.
Some time prior to Ar'alani's promotion to Commodore, she and Senior Commander Mitth'raw'nuru "Thrawn" of the Chiss Ascendancy's Expansionary Defense Fleet helped the Garwian Unity fend off an attack by Lioaoin pirates over the Garwian colony world of Stivic. That event came to be known as the Stivic incident.
The Unity's Ruleri invited Thrawn and Ar'alani to the Garwian homeworld and capital planet of Solitair under the guise of thanking them for assisting their defense. The two Chiss officers considered it a great honor to be brought before the Garwian Unity's ruling body to be thanked. When they landed on Solitair, they were greeted by Security Chief Frangelic, the same officer who had sent out the distress call that led the Chiss to aid in Stivic's defense. Frangelic gave them a tour of the capital city, teaching them about Garwian culture including the Creators' Market and events such as remembrance parties.
After their immersion in Garwian culture, Ar'alani confided in Thrawn that until that point, she had seen non-Chiss "aliens" as something akin to intelligent animals, but she now saw them as people. The commodore believed Thrawn must have always seen aliens as people, but Thrawn replied that he saw them as assets first and people second.
As Thrawn, Ar'alani and Frangelic neared the Solitair planetary security center, emergency klaxons started to blare in the market. The Security Chief exclaimed to his Chiss guests that Solitair was under attack, telling them to hurry to the underground security center. As they ran, they saw two Lioaoin ships overhead.
Once inside the bunker, the Chiss officers told their hosts that standard Chiss Defense Force protocols forbade them from being present in a foreign nation's situation room. A general of the Garwian military insisted that Thrawn and Ar'alani were guests, and that "guests must be protected" in the event that the Lioaoin "invaders" break through. Thrawn replied that the Garwian defense platforms in orbit should be "more than adequate" to protect Solitair from two warships, but Frangelic countered by asking what if more lie in wait. Frangelic then begged Thrawn for any tactical information the Chiss could provide.
Thrawn analyzed the situation on the tactical displays, sighting weaknesses in the Lioaoin ships. However, he deferred to Ar'alani's insistence that the Ascendancy must remain neutral. Frangelic implored Thrawn, insisting that this situation was even more dire than the Stivic incident had been. Thrawn began to relent, but just before he could share information about the Lioaoi's tactical blind spots, Ar'alani interrupted him. The Commodore had noticed that the Lioaoin ships were not in fact attacking the defense platforms and none of the Garwian officers present were watching their monitors or directing defenses. Rather, all of their stares were fixed on Thrawn. Ar'alani discovered that her communications with her Chiss heavy cruiser Destrama were being jammed.
Thrawn insisted that the Garwian officers lift their jamming, at which point Ar'alani heard an officer tell her that the Lioaoi had come to negotiate the surrender of the Lioaoin Regime. The Garwians' forces were ignoring the Lioaoi's plea and attacking them. Her officer had been trying to reach her for orders. Ar'alani realized that the Garwians invited them to Solitair under false pretenses, claimed to be raided by pirates, and maneuvered them into bending their non-intervention protocols to assist in their war. She speculated that the Garwians sought conquest of some of Lioaoin space, which the general confirmed. He told the Chiss that more insights into the Lioaoins' vulnerabilities would have been "useful", but thanked them for their "sufficient" earlier assistance at Stivic.
This manipulation angered Thrawn and Ar'alani. Thrawn asked Ar'alani for permission to order the Destrama to fire on the Garwian defense platforms. Ar'alani replied that she would like to do so and that it would be "fully justified," but the Ascendancy's military protocols forbade them from performing such an action.
At that point, a Garwian officer told the general that the Lioaoi were breaking off their attack. The general said they were no doubt recalled to defend their worlds, which he called "a futile gesture." He asked Ar'alani if she wished to depart. The Chiss commodore replied with a threat that Thrawn could penetrate the Garwian's weaknesses just as well as Lioaoi ones and told them to hope they never encounter the Chiss again.
Following Thrawn's unauthorized assistance to the Garwians in violation of the Ascendancy's non-intervention policy, the Defense Hierarchy Council demoted Thrawn from Senior Commander to Mid Commander. However, due to the influence of Thrawn's Mitth family Patriarch Mitth'oor'akiord "Thooraki" and Supreme General Ba'kif, Thrawn was made a Trial-born of the Mitth and given command of the heavy cruiser Springhawk and Picket Force Two. Shortly before Thrawn was to take command of the Springhawk, he and his friend Syndic Mitth'ras'safis "Thrass" were assigned a special mission by Patriarch Thooraki to assist the Stybla family. Thrawn initially protested, as he was due aboard the Springhawk in several hours. Thrass winced at Thrawn's comment, correctly deducing that the Defense Hierarchy Council was eager to send Thrawn far away from the Ascendancy on a pirate hunt so as not to cause embarrassments like he had at Solitair.
Years after the skirmish, Thrawn held the rank of Senior Captain in the Chiss Expansionary Defense Fleet. Upon the senior captain's return to Solitair, Frangelic told him that most of the Ruleri considered Thrawn's cessation of assistance and threat of attack a "betrayal." Frangelic, now promoted to Second Defense Overlord, assured Thrawn that his own memories of the Chiss's visit to Solitair were better than the Ruleri's.
The mission to and skirmish above Solitair appeared as a flashback in the 2020 novel Thrawn Ascendancy: Chaos Rising by Timothy Zahn as the first installment of his Star Wars: The Ascendancy Trilogy.