The Assault on Ruul occurred early in the Galactic Civil War.
Grand General Malcor Brashin, tracking the Millennium Falcon, arrived in the Ruul system and discovered that, while the Falcon had fled to Alderaan, Rebel forces had taken control of the central computer complex on Ruul.
Brashin landed troops under the command of Captain Brenn Tantor. Under the supervision of his training officer, Captain Beri Tulon, Tantor led a force that took back several mines captured by the Rebels and seized a Rebel base before passing through a choke point of Rebel turrets. From there, Tantor recaptured the computer facility. His brother Dellis was inserted into the facility to slice into Rebel records.
The network of remote relay beacons set up by Dellis Tantor
The relay on the facility, however, had been damaged in the attack, making it impossible to transmit the data to the Star Destroyer Inquisitor in orbit. Fortunately, Dellis discovered a cache of remote relay beacons in the facility. Brenn smashed through the remaining Rebel positions, clearing the way for Dellis to lay a network of beacons to an uplink tower three kilometers away. From there, the information was quickly beamed to Inquisitor, where it was determined that the Rebels had seized several energy collectors on Sarapin. Brashin and the Tantors continued there minus Tulon, who was reassigned by Brashin after he promoted Tantor over Tulon's head.
The Imperial assault on Ruul was mentioned by Brenn Tantor in the video game Star Wars Galaxies. However, the game confused the planet Ruul with Sriluur's moon of Ruul.