The ship was manufactured by the shipwright Raith Sienar's Republic Sienar Systems during the last days of the Galactic Republic.
The ship had very little flight time and traveled from the shipyard over Castell directly to Jakku where it remained for years until the Battle of Jakku in 5 ABY. Counselor to the Empire Gallius Rax intended to take the Imperialis into the Unknown Regions with the former Commandant Brendol Hux, his son Armitage Hux, and his child soldiers to restart a new Empire.
However, Rae Sloane took his place and travelled with the Hux's and the child soldiers into the Unknown Regions. The ship was piloted by a Sentinel droid that was programmed to serve the Emperor's will even after his death. After traveling for several months, they rendezvoused with Emperor Palpatine's flagship Eclipse, which had been dispatched in advance as part of the Emperor's posthumous Contingency plan.
- Star Wars: Timelines