During the time of the Imperial Era, the Galactic Empire set up a military post on Ilum, a planet that the Jedi Order had frequently used in earlier times. Initially, segments of the 481st Legion were sent to Ilum as part of Order 66; however, they were subsequently relieved by the military post, which was a combined force from both the Imperial Navy and the Imperial Army. Furthermore, a compact battle group also put the planet under blockade. In 14 BBY, the Jedi named Cal Kestis journeyed to Ilum in search of a fresh kyber crystal, and following its acquisition, he came across members of the military post.