- "Don't encourage them, kid....They'll turn you into a Mandalorian. You wouldn't want that."
After Order 66 was enacted and Palpatine established the Galactic Empire, Galaar Squad was disbanded. Ennen, along with his squadmate, Bry, were combined with Omega Squad's Niner and Darman Skirata to form Squad 40 of the 501st Legion. On their first mission as a squad, they were sent to the planet Celen to capture Jilam Kester, an Antarian Ranger who was helping Jedi escape from the Empire. Upon storming the building where Kester was residing, the commandos came face to face with Jedi Master Iri Camas, who had previously led clone commandos as commander of the Republic's Special Operations Brigade. Camas distracted the commandos, allowing Kester to escape, and ended his own life by igniting a gas line and causing the building to explode. Bry was killed in the explosion, while the rest of the squad managed to escape.
Following Bry's death, Ennen became withdrawn and depressed. When Squad 40 was sent on a mission to hunt down a Jedi on Coruscant, they successfully trapped the man. Ennen killed him; but they later discovered that the supposed Jedi was just a simple thief who had happened upon a lightsaber. Later, in the refreshers of the barracks, Ennen committed suicide, shooting himself with his DC-15s side arm blaster.
- Imperial Commando: 501st (First appearance)