During the Clone Wars, a short time after the Malevolence Campaign, another Separatist campaign was launched by General Grievous, the Supreme Martial Commander of the Separatist Droid Army. Grievous moved his battle droids and fleet against Republic forces in the Outer Rim Territories, pushing through the region and winning numerous battles. To locate and destroy Republic fleets, Grievous used a listening post named Skytop Station on the Ruusan moon.
Grievous's victories caused the Republic's foothold in the Outer Rim to slip. Jedi General Anakin Skywalker and his battle group fought against Grievous's forces in the campaign, but his forces failed to stop his advance. After the destruction of the battle group at Falleen, Grievous moved his forces to take the strategic Mid Rim world of Bothawui. It was here that the Republic, under the command of General Skywalker, finally stopped Grievous's advance in the Battle of Bothawui, though Skywalker lost his astromech unit, R2-D2. The droid, who contained vital Republic intelligence, was located in the aftermath of the battle by Separatist-allied scavenger Gha Nachkt, while Skywalker was gifted a new astromech droid, R3-S6, who was secretly a Confederate spy that reported directly to Grievous. Skywalker, R3, and the Jedi's Padawan, Commander Ahsoka Tano, boarded Nachkt's freighter, the Vulture's Claw, to search for R2, though the scavenger hid R2 from sight 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.
Contacting the team aboard the Twilight over hologram, Jedi General Obi-Wan Kenobi, who had yet to develop the fondness for R2 he had by his later life, chastised his former Padawan for risking everything to save a droid. Skywalker disagreed, explaining to Tano that R2 was more than a droid, as he was true friend to them. Elsewhere, Grievous had escaped Skytop Station as well. Despite the destruction of his spy station, he had still managed to ambush a number of Republic fleets. In fact, his victory at Falleen had mitigated the defeat he suffered at Bothawui that had cost the CIS their advance.