Attack of the Clones may have marked the beginning of the Clone Wars, but the Battle for Geonosis lasted long after Count Dooku and the Separatists were forced to flee the system. The Geonosians, in addition to hosting the first capital of the Confederacy of Independent Systems, were also responsible for secretly designing the Death Star. By most counts, the conflict on their arid planet, and its aftermath, would last long into the Imperial era, culminating in the mass extermination of its native species.
Geonosis played a major role in the climax of Attack of the Clones. After Obi-Wan Kenobi tracked bounty hunter Jango Fett to the system, he discovered that the planet had joined the Separatist movement, and its leader, Poggle the Lesser, had pledged its vast droid foundries to Count Dooku. The Jedi Order quickly dispatched hundreds of its knights in an attempt to capture the Separatist leaders, but failed to prevent an escalation of the conflict. This resulted in the deployment of the newly created clone army to reinforce the beleaguered knights and force a retreat from the Separatists. However, the battle for the planet was far from over.
Season 2 of The Clone Wars would return to the planet, with the Republic facing a new threat from Poggle and his factories. The Republic underestimated the Geonosians’ loyalty to Count Dooku, and left only a minor garrison behind after taking control of the world. A covert mission carried out by Padme Amidala revealed that the Banking Clan was funding a new droid factory on the planet, which would serve as the testing ground for hi-tech indestructible Super Tanks. After the garrison was overrun, the Republic, hoping to shut down droid production for good, was forced to return to Geonosis.
The initial assault, depicted in episode 5, “Landing at Point Rain”, was very nearly a catastrophic failure. Meeting stiff resistance from the Separatists, the clone army struggled to push forward to the factory. Knowing they would be unsuccessful in a direct attack, Anakin Skywalker and Luminara Unduli distracted the droids while their padawans Ahsoka Tano and Barriss Offee snuck inside and destroyed the factory from within. With the mission completed, Separatist forces were badly damaged and the search for Poggle began. Pursuing him to an underground hive, the Jedi uncovered a secret plot by Poggle and the Geonosian Queen to utilize hive-mind control worms to defeat the Republic forces. Ultimately the queen was killed and Poggle was taken into custody.
The Second Battle of Geonosis had major ramifications for the galaxy. The CIS was forced to produce droids elsewhere, but more importantly, it resulted in the capture of Poggle. After two years of interrogation, Poggle divulged aspects of the Geonosian ultimate weapon to Orson Krennic, and pledged the population of his homeworld to the Republic Special Weapons Program. This was a ruse by Poggle to sabotage the project and arrange for his escape back to the Separatist leadership, but after the conclusion of the clone wars, and his execution by Darth Vader, Poggle’s subjects were left in the enslavement of the Empire to construct the Death Star.
When the security of the Death Star project became increasingly difficult, Grand Moff Tarkin moved its construction to Scarif. He then ordered the extermination of Geonosis, deploying poison gas to wipe out over 100 billion natives. Saw Gerrera, obsessed with discovering what the Empire was building, discovered the genocide in Season 3 of Star Wars Rebels. With the assistance of the Spectres, he captured the sole surviving Geonosian Klik-Klak but was unable to understand the creature’s warnings of the battle station. The Geonosian was protecting the last surviving egg of a queen, and the crew convinced Saw to let it go, allowing its species a chance to recover. The Spectres left without further clues on what had been occurring on Geonosis, but Saw Gerrera would continue his obsessive chase for answers until his death in Rogue One.