Early in the Clone Wars, Jedi Master Obi-Wan Kenobi of the Jedi High Council was sent on a mission to Cato Neimoidia to find the cause of the Cadesura disaster on the planet Cato Neimoidia in the Colonies region of the galaxy. Joined by his former Padawan Anakin Skywalker, who had recently become a Jedi Knight and disobeyed orders by arriving on planet to help Kenobi, the two Jedi became involved in a dangerous incident, which nearly cost Kenobi his life. During the mission, Kenobi first met Dark Acolyte Asajj Ventress, the Sith apprentice of Confederacy of Independent Systems leader Count Dooku. Skywalker considered it one of many times he saved his former mentor, yet Kenobi disagreed.
In 22 BBY, the political crisis ongoing in the Galactic Republic over thousands of star systems attempting to secede and form the Confederacy of Independent Systems erupted into full-scale war at the First Battle of Geonosis, beginning the Clone Wars. Although Viceroy Nute Gunray, leader of the Trade Federation, was a member of the Executive Separatist Council, the Federation officially claimed neutrality in the conflict, stating that Gunray was an extremist who no longer represented its views. As a result, the Colonies planet Cato Neimoidia, where the corporation's headquarters were located, was also considered neutral.
A few weeks after the beginning of the war, a bombing occurred in Zarra, Cato Neimoidia's capital city, which resulted in significant damage and deaths. With the planet's neutrality threatened, the Republic and Confederacy both sent emissaries to investigate the incident. The Republic was represented by Jedi Master Obi-Wan Kenobi, while Count Dooku, the fallen Jedi turned Sith Lord who publicly led the Separatists, sent his apprentice, the assassin Asajj Ventress.
Arriving on Cato Neimoidia, Kenobi was met by Minister Alluv Eyam. He also met Ventress, who made a show out of inspecting him for recording devices and took an interest in an elaborately-plated Kenobi had received as a gift from a friend. Claiming she had never met a Jedi before, Ventress stated that Dooku had spoken highly of the Jedi Order. While Kenobi's belongings were delivered to his assigned quarters, the Neimoidians took him and Ventress on a brief tour of Zarra.
During the tour, Kenobi attempted to suss out Ventress' personality and motivations by questioning her, although she deflected them. Kenobi was, however, intrigued by a slip of the tongue the Dark Acolyte made where she referred to Dooku as "Master", wondering if it referred to the Separatist hierarchy or something more. After the tour, the visitors were taken to the blast site, where an inspector showed Kenobi and Ventress the damage that had been done, discussing casualties and those who had survived. Ventress noticed something and asked that the shuttle be stopped, pointing out a series of six blast points to Kenobi which suggested a deliberate attack. The weeks Kenobi had spent getting to know the clone troopers of the Republic Military suggested to him that the attack was some kind of military operation, which Ventress directly questioned him about. As Ventress wondered what they would find in other areas, Kenobi diplomatically suggested that it required investigation.
Eyam said he would be bringing them to view the damage at the surface level, which Kenobi agreed to, requesting to see as much of the destruction as possible for investigative purposes. Kenobi also suggested to Ventress that they might find common ground between their governments, to which Ventress responded that such a thing might be possible if he could win her over.
As the mission continued, Kenobi teamed up with Neimoidian Royal Guardswoman Ruug Quarnom. Jedi Knight Anakin Skywalker, Kenobi's recently-promoted former Padawan, disobeyed orders to come to Cato Neimoidia, accompanied by promising but conflicted Jedi youngling Mill Alibeth and the astromech droid R2-D2. In the course of events, the Jedi became involved in a dangerous incident which nearly cost Kenobi his life, although Skywalker claimed to have saved him; in the Grand Theatre of Judgment, Kenobi called upon his hidden lightsaber upon being surrounded by Neimoidian guards, only for Skywalker to rush in to Kenobi's surprise, helping to block the blaster bolts but also getting in the way of Kenobi's blade before Kenobi could do it himself. Skywalker and Ventress then clashed, with Ventress revealing she already knew him.
The Cato Neimoidian government's attempts at remaining neutral ultimately ended in failure. The planet eventually fell under Separatist control, which inspired the Republic to launch a conquest of Cato Neimoidia. The world continued to be a center for fighting afterward, with Skywalker, arriving alongside his apprentice Ahsoka Tano and his 501st Legion, returning to the planet when the Separatists tried to take back Cato Neimoidia. The Separatist victory led to another Battle of Cato Neimoidia during the Outer Rim Sieges.
By 19 BBY, the final year of the Clone Wars, Skywalker considered himself to have saved Kenobi's life on at least nine other occasions, including during the Battle of Coruscant. In the aftermath of that battle, Skywalker mentioned to Kenobi that he had saved him ten times, but Kenobi corrected him to nine, insisting that what had occurred on Cato Neimoidia did not count.
The mission to Cato Neimoidia was first mentioned, indirectly, in the 2005 film Star Wars: Episode III Revenge of the Sith. It first appeared in the 2022 novel Brotherhood, written by Mike Chen.
In the Star Wars Legends continuity, the event was depicted as the Battle of Cato Neimoidia in the 2005 novel Labyrinth of Evil, written by James Luceno and set immediately prior to the events of Revenge of the Sith. "Anakin Skywalker," a 2021 booklet in the Star Wars Encyclopedia published by De Agostini, gave a description of Kenobi and Skywalker's mission which roughly corresponded with the Legends depiction, stating they had gone on the mission just before the Battle of Yerbana, which occurred just before the Battle of Coruscant that opens Revenge of the Sith. Chen has stated fans are able to continue to believe the events of Labyrinth of Evil are the business mentioned in Revenge of the Sith because nothing in his book contradicts its events.
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