The Unidentified Imperial officer was an Imperial officer in the Imperial Army that was in command of the Imperial garrison on Sullust during the Galactic Civil War. Shortly before the Battle of Endor, during the Battle of Sullust, he commanded the Imperial troops during the Rebel attack. When Renegade Squadron, the Rebel Alliance's elite fighting force, discovered that their plan to lure away some of the Imperial fleet from Endor, while General Solo's strike force could land, had not work, they attempted to make it off Sullust.
The officer quickly ordered his bounty hunter ally, IG-88, to keep the rebel preoccupied while he set gravity well projectors to keep the rebels trapped on Sullust. When Renegade Squadron defeated IG-88, the commander activated shields to protect the gravity wells. Renegade Squadron's commander, Col Serra, ordered his men to get the codes to the shields so they could disable the projectors, which the officer was holding. Renegade Squadron killed the officer and the stormtroopers protecting him and took the codes, shut down shields, and destroyed the gravity well projectors. This allowed Renegade Squadron to take control of Sullust and make it to Endor in time.