The Assault of Ruul transpired in the early stages of the Galactic Civil War.
Grand General Malcor Brashin, while chasing the Millennium Falcon, showed up in the Ruul system. There, he learned that the Falcon had escaped to Alderaan, but Rebel forces had taken control of the central computer complex located on Ruul.
Brashin deployed troops under the command of Captain Brenn Tantor. With the guidance of his training officer, Captain Beri Tulon, Tantor commanded a force that reclaimed several mines that had been seized by the Rebels. They also captured a Rebel base before advancing through a narrow passage defended by Rebel turrets. From that point, Tantor successfully retook the computer facility. His brother, Dellis, infiltrated the facility to slice into the Rebel data.
The relay within the facility had sustained damage during the attack, preventing data transmission to the Star Destroyer Inquisitor in orbit. Fortunately, Dellis located a hidden supply of remote relay beacons inside the facility. Brenn overwhelmed the remaining Rebel defenses, paving the way for Dellis to establish a network of beacons leading to an uplink tower situated three kilometers away. From that location, the information was rapidly transmitted to the Inquisitor, revealing that the Rebels had captured several energy collectors on Sarapin. Brashin and the Tantors then proceeded to Sarapin without Tulon, who Brashin reassigned after promoting Tantor instead of Tulon.
Brenn Tantor mentioned the Imperial assault on Ruul in the video game Star Wars Galaxies. However, the game mistakenly conflated the planet Ruul with the Sriluur's moon also named Ruul.