Admiral Jion Trynn served the Imperial Navy during the Galactic Civil War. In 0 BBY, he led a task force of two Imperial-class Star Destroyers, Adjudicator and Relentless to Gerrard V to quell a local uprising. A local rebel force had taken the capital, Harazod, and Trynn deployed forces to retake the city after destroying the small rebel navy in orbit.
Trynn attempted to reach a compromise, offering surrender terms to the rebel leader, General Camon Udeon, but they were refused. The admiral pulled his troops out of the city and bombarded the urban center of Harazod from orbit. Trynn suspected that the rebels were linked with Mon Mothma's Alliance to Restore the Republic, but without prisoners to interrogate, he could not be certain.