Brannij, a Captain, was in command of the Bastion, which was an Imperial II-class Star Destroyer. In the Battle of Kathol System, Brannij showed up to defend Kathol from the assault by the New Republic, with Bothan commander Kursk Mal'ia leading the charge.
As the tide of the battle shifted against the Imperials, Brannij noticed that the commanding Moff, Kentor Sarne, only cared about his own survival. So, Brannij made a distraction, commandeered the Bastion along with the surviving Imperial vessels, and jumped into hyperspace to escape.