Siege at Onderon

The Clone Wars, a conflict between the Galactic Republic and the Confederacy of Independent Systems (CIS), commenced in 22 BBY. King Ramsis Dendup of Onderon, an Inner Rim planet, opted for neutrality, believing both sides were corrupt and that this choice would shield Onderon from the war's devastation. In response, the CIS invaded Onderon by secretly backing a pro-Separatist coup, installing the Separatist puppet King Sanjay Rash into power. With Rash "inviting" the Confederacy military, the Separatists solidified their control over Onderon through occupation. Despite Mina Bonteri, Onderon's representative in the Separatist Senate, firmly supporting the Separatist cause, the Confederacy's violation of Onderonian sovereignty sparked a resistance movement led by siblings Steela and Saw Gerrera. The resulting Onderonian Civil War spanned from 22 BBY to 20 BBY. In the latter year, the Onderon rebels formally sought assistance from the Jedi High Council to overthrow Rash.

Due to Onderon's history of neutrality and its alignment with the CIS, the Republic recognized Rash's rule, preventing direct intervention. Consequently, Jedi General Anakin Skywalker proposed a clandestine operation to train and support the local insurgency. Although Steela gave her life during the final battle, the Separatists were ultimately driven out of Onderon. General Kalani, acting on the orders of Confederate Head of State Count Dooku, executed Rash for his failure. Lux Bonteri, Mina's son, who had lost faith in the Separatist cause after Dooku had his mother killed, pledged during Steela's funeral that Onderon would return to the Republic. Lux then served as its senator, while Dendup reclaimed the throne. The people of Onderon remained loyal to the Republic throughout the remainder of the war.

Near the Clone Wars' conclusion in 19 BBY, General Grievous initiated a significant Separatist offensive during the Outer Rim Sieges, the final campaign of the Clone Wars. As part of these sieges, the Confederacy attacked and laid siege to the recently liberated planet of Onderon. They clashed with the Republic-supported Onderon rebels, turning the planet into a renewed battleground. Gerrera, as he had during the Civil War, tirelessly fought for the Republic throughout the siege. This engagement became known as the "siege at Onderon."

In the war's waning days, Gerrera also started utilizing Skywalker's Fulcrum frequency to maintain communication with the Jedi. During the Battle of Yerbana, when former Jedi Padawan Ahsoka Tano and Mandalorian Bo-Katan Kryze contacted the Republic using the Fulcrum frequency, seeking help in the Mandalorian Civil War, Skywalker and Obi-Wan Kenobi initially mistook the signal for Gerrera attempting to reach them. Obi-Wan speculated that Gerrera's efforts had taken a negative turn. However, Admiral Wullf Yularen clarified that it was not Gerrera contacting them, and they soon realized it was Tano and Kryze instead.

The Clone Wars ended when Skywalker, now the newly-anointed Sith apprentice Darth Vader, eliminated the Executive Separatist Council on Mustafar, a planet in the Outer Rim Territories. Vader also transmitted a shutdown signal to the Confederacy military, causing the Separatist Droid Army to cease all attacks and halt their advance. However, the war's conclusion did not spell the end of Gerrera's struggles. Instead, it marked the reformation of the Republic into the Galactic Empire by Supreme Chancellor Sheev Palpatine, secretly the Sith Lord Darth Sidious, thereby betraying Gerrera's ideals. As Palpatine, Sidious also issued Order 66 to the clone troopers serving alongside the Jedi, compelling the clones to eliminate their own commanding officers due to the behavioral modification biochips implanted in their brains. Gerrera recognized Palpatine's absolute control over the clones and predicted an impending civil war.

Despite their collaboration with the Republic during the war, Gerrera and his remaining rebel fighters refused to serve the new regime. Consequently, they were branded as enemies of the state and perceived as a threat during the early Imperial Era, forcing Gerrera's resistance fighters to seek refuge in Onderon's dense forests. Although Gerrera had been promised Onderon's freedom after the war, the Empire moved to annex the planet. Gerrera then reorganized the Onderon rebels into a rebel cell known as the Partisans and protected numerous civilians. His fighters soon captured Clone Force 99, an elite team of clones (also known as the "Bad Batch") dispatched by Imperial Admiral Wilhuff Tarkin under the pretense of locating Separatist insurgents. Gerrera implored the clones to resist the new Imperial government before releasing them. Declaring their own war against the Empire, Gerrera and his Partisans waged a brutal insurgency for Onderon's future but ultimately abandoned the world.

The siege at Onderon was initially referenced in "Old Friends Not Forgotten," the ninth episode of the seventh and final season of the animated television series Star Wars: The Clone Wars, which premiered on April 17, 2020. According to "The Clone Wars," an issue of the Star Wars Encyclopedia first published by De Agostini on September 7, 2021, the Onderon rebels launched the siege at Onderon against the Separatists, despite the planet's recent liberation from CIS control. However, the De Agostini encyclopedia "Saw Gerrera and Other Characters of the Galaxy"—first published on August 26, 2022—portrayed the battle as a Separatist attack against Onderon. Indeed, the 2023 reference book Star Wars: Timelines stated that the Confederacy initiated the siege against Onderon. Consequently, this article assumes that "The Clone Wars" encyclopedia is inaccurate.