In the year 18 BBY, a brief conflict unfolded above the Chiss Ascendancy planet of Jamiron. This clash involved the Tahmie and Droc families, both belonging to the Ascendancy, amidst a crisis within the Ascendancy itself. The Grysk coordinator known as "Jixtus" had manipulated several Chiss families into engaging in hostilities against one another. This event followed closely after a prior engagement between the two families, which had taken place near the astronomical object Csaus. To address the situation, the Chiss governing body, known as the Syndicure, dispatched the Chiss Expansionary Defense Fleet Nightdragon man-of-war named Vigilant, under the leadership of Admiral Ar'alani. Upon the warship's arrival at Jamiron, it discovered eighteen starships from both families actively engaged in combat.
After the admiral's commands to cease fighting were ignored by the involved families, Ar'alani's ship deployed plasma spheres, a type of weapon designed to disable vessels, targeting all participants in the conflict. Once all eighteen ships from the Tahmie and Droc factions were rendered inoperable, the Vigilant employed its tractor beams to separate the disabled vessels. Following this encounter, Ar'alani had a meeting with Supreme Admiral Ja'fosk of the Ascendancy's Defense Hierarchy Council. Ja'fosk informed her that the Syndicure was displeased with her intervention, considering it a humiliation for both families involved. He then instructed her to return to the planet Sposia, where the Vigilant had been stationed before its deployment to Jamiron.
Back in 18 BBY, "Jixtus," who coordinated the Grysk species, journeyed across the Chiss Ascendancy, offering Grysk warships to the Patriarchs of the Ascendancy's Nine Ruling Families and its Forty Great Families. His true intention was to instigate conflict between the families, weakening them sufficiently to allow his fleet to launch a final assault against the Ascendancy. Among the many families drawn into this crisis were two Great Families, the Tahmie family and the Droc family, who already had a history of animosity.
Before renewing their conflict above the planet of Jamiron, they had fought over the astronomical object Csaus. In response, the Chiss governing body, the Syndicure, dispatched the Chiss Expansionary Defense Fleet Nightdragon man-of-war Vigilant (Vigilant) of Picket Force Six, under the command of Admiral Ar'alani, to de-escalate the situation. Due to Jixtus's travels around the Ascendancy aboard the Kilji war cruiser Whetstone, the Syndicure feared an imminent attack, and thus recalled Expansionary Defense Fleet warships to protect the Ascendancy's worlds. The Vigilant was redeployed to Jamiron from the planet Sposia, with the Syndicure hoping it would arrive before the conflict intensified.
Upon the man-of-war's arrival, it found eighteen starships from the Tahmie and Droc families engaged in battle. These included patrol ships, armed freighters, and at least two gunboats from each of the Tahmie and Droc factions. A Tahmie patrol cruiser attempted, unsuccessfully, to coordinate the Tahmie forces. Ar'alani issued a command via a full broadcast for all combatants to cease hostilities, but received no response. She repeated her order, finally receiving a reply from a Tahmie aboard the Tahmie patrol cruiser. The Tahmie argued that she lacked jurisdiction in the current engagement, as the Vigilant was an Expansionary Defense Fleet vessel, and warned that the Syndicure would disapprove if the Nightdragon attacked any of the combatants.
Nevertheless, the Vigilant launched [plasma spheres](/article/plasma_sphere], a type of weapon that disables starships, at all the vessels, beginning with the Tahmie patrol cruiser from which the opposition had originated. After all eighteen ships were neutralized, Ar'alani's crew employed the ship's tractor beams to separate the disabled vessels. To make it harder for the neutralized ships to resume the battle, the Nigthdragon moved the ships to different orbital shells.
Ar'alani soon communicated with Supreme Admiral Ja'fosk of the Chiss Defense Hierarchy Council, who told her that her actions had angered the Syndicure. Some of the ruling body's members, however, were grateful that she had prevented a battle in a busy area, saving civilian ships and cargo. Ja'fosk then instructed the admiral to return to Sposia. Eventually, the Chiss, led by Senior Captain Mitth'raw'nuruodo, known as "Thrawn," engaged Jixtus's fleet over the planet Thrawn had code-named Sunrise, where a Chiss fleet defeated the Grysk forces.
The Jamiron skirmish is featured in the 2021 novel Thrawn Ascendancy: Lesser Evil, the concluding book in Timothy Zahn's Star Wars: The Ascendancy Trilogy.