During the Clone Wars, not long after the events of the Malevolence Campaign, General Grievous, the Supreme Martial Commander of the Separatist Droid Army, initiated another major campaign for the Separatists. His battle droids and fleet were deployed by Grievous against Republic forces located in the Outer Rim Territories, achieving multiple victories and pushing further into the region. To find and eliminate Republic fleets, Grievous utilized a listening post called Skytop Station, situated on the Ruusan moon.
The Republic's position in the Outer Rim was weakened due to Grievous's successes. Jedi General Anakin Skywalker and his battle group engaged Grievous's forces during this campaign, but they were unable to halt his progression. Following the destruction of the battle group at Falleen, Grievous shifted his focus to capturing Bothawui, a strategically important world in the Mid Rim. It was at the Battle of Bothawui that the Republic, led by General Skywalker, finally brought Grievous's offensive to a halt, although Skywalker's astromech unit, R2-D2, was lost in the process. Gha Nachkt, a scavenger allied with the Separatists, discovered the droid, which held crucial Republic intelligence, following the battle. Skywalker received a replacement astromech droid, R3-S6, who was secretly a Confederate spy reporting directly to Grievous. Skywalker, R3, and Commander Ahsoka Tano, the Jedi's Padawan, boarded Nachkt's freighter, the Vulture's Claw, to locate R2, but the scavenger concealed R2 to prevent the Jedi from recovering him.
After Skywalker attempted to scout ahead for signs of Skytop Station and a transmission from R2 led Skywalker and the others aboard the Twilight to the outpost, the Jedi General, Tano, R3, Clone Captain CT-7567 "Rex," and the rest of their infiltration team boarded the listening post. During this skirmish, Tano attempted to hold her own against Grievous and learned of R3's true loyalties. Elsewhere, Skywalker rescued R2 from Grievous's IG-100 MagnaGuards, and, after R3 arranged for a confrontation between battle droids and the infiltration team, Rex detonated their charges, dooming Skytop Station to fall to its destruction. Tano took advantage of the sudden rumble to escape Grievous. R2, traveling to a boardwalk, then managed to open the hangar doors to allow the Twilight to escape, but he was also attacked by R3. After throwing his rival astromech droid off the station, resulting in the Separatist unit being struck and killed by debris, R2 was then rescued by Skywalker in his Delta-7B Aethersprite-class light interceptor.
Obi-Wan Kenobi, who had yet to develop the fondness for R2 he had by his later life, contacted the team aboard the Twilight via hologram and scolded his former Padawan for risking everything to rescue a droid. Skywalker countered, telling Tano that R2 was more than just a droid and was a true friend to them. Grievous also managed to escape Skytop Station. Despite the loss of his spy station, he had successfully ambushed several Republic fleets. Ultimately, his victory at Falleen offset the defeat he experienced at Bothawui, which had halted the CIS advance.