He dressed in the ground assault armor favored by AT-AT commanders. He looked like a formidable Imperial officer, however, while he was a good officer, he had no desire to die needlessly for the Imperial cause. He was known to talk his way out of the worst situations only to reappear later to win the day for the Empire.
He was stationed on the forest moon of Endor during the Battle of Endor and was in command of a speeder bike patrol. While his group were on their way to the shield generator, they came across a group of rebels roughly four kilometers from the generator.
The rebels were able to wipe out his entire group, two scout troopers on their speeder bikes and Perrn, along with four assault troopers and a driver in a landspeeder, but Perrn himself was able to escape by informing the group about the siege tower making its way to the shield generator.