In 22 BBY, at the start of the Clone Wars between the Confederacy of Independent Systems and Galactic Republic, the Confederacy invaded the world of Onderon in the Inner Rim Territories after covertly supporting a pro-Separatist coup. Legally speaking, the Confederacy military was "invited" to Onderon by Sanjay Rash, a Separatist puppet who came to power through the coup. In reality, however, the incident was an invasion, with Rash even having been appointed by Count Dooku.
During the Clone Wars, the Onderonian king, Ramsis Dendup, had refused to side with either the Galactic Republic nor Confederacy of Independent Systems due to the corruption in both and hoped a neutral stance would spare Onderon from the damages of the fighting. With some under his rule deeming him a coward but seeing the moment as a chance to grab power, Sanjay Rash, who deemed an alliance with the Separatists the best way to ensure Onderon's future, managed to become the new king through unclear means. The Confederacy covertly supported a coup that brought him to power.
Rash was appointed to the position of king by Count Dooku to serve as a Separatist puppet. Legally speaking, however, the planet withdrew from the Republic on Rash's order. The Droid Army was "invited" to Onderon to help with security, but the action was truly an invasion. Nevertheless, any open response from Republic would be branded an act of aggression thanks to Rash. However, the invasion and Rash's appointment inspired a resistance movement that began the Onderonian Civil War.
- Star Wars: Battles that Changed the Galaxy