In its earliest ages of civilization, Onderon was a world marked with savage jungles that were filled with dangerous creatures. To survive, the primitive human inhabitants of the planet protected themselves behind the walls of fortified settlements. Over time, these grew to become enormous walled cities, like the planet's capital, Iziz. In the modern era, during the time of the Clone Wars, the planet's monarch King Sanjay Rash allied Onderon to the Confederacy of Independent Systems. Many Onderonians, however, refused to recognize the legitimacy of Sanjay's rule -- they preferred the neutral stance championed by former monarch Ramsis Dendup, whom Rash ousted.

During the Clone Wars, the Galactic Republic had little recourse with worlds that willingly sided with the Separatist Alliance -- the rules of engagement enforced by the Senate and the Jedi Order contained the battlefield to contested worlds. But what of planets where the Separatist banner did not garner unanimous support among its populace? When an insurgency on Onderon refused to recognize the legitimacy of its monarch and began a rebellion to oust both the king and the Separatist influence on the planet, Anakin Skywalker saw an opportunity: If the Jedi could train and equip the rebels on Onderon, these freedom-fighters would keep the Separatists occupied during the Clone Wars.

A young native of Onderon, Steela and her brother Saw were members of the insurgency that opposed the rise of King Sanjay Rush, and Rush's alignment of the planet to the cause of the Separatists during the Clone Wars. Not as boisterous or as outspoken as her brother, Steela was nonetheless firmly dedicated to the cause of Onderonian independence. She was not one for impassioned speeches or political rhetoric. These were not her areas of expertise, and she felt far more comfortable peering through the macroscope of her blaster rifle. A crack shot, Steela racked up an impressive number of droid kills with precise headshots fired from the cover of canopy jungle.

The leader of the royal guard and native military forces of Onderon, General Tandin was a proud patriot devoted to protecting the crown and the sanctity of the Onderonian people. When the planet sided with the Separatists during the Clone Wars, Tandin supported the new king, Sanjay Rash, despite his misgivings of offworld interlopers interfering in Onderonian affairs. The people of Onderon, though, began to reject Rash's rule, and an insurgency began targeting the battle droid forces stationed on the planet. Tandin had difficulty waging war against his own people, and cared little for the military support and tactical advice offered by the emotionless droids sent by the Confederacy to reinforce his defenses.

The son of Separatist Senator Mina Bonteri, Lux was young, idealistic, and skeptical of the aims of the Republic and the Jedi Knights. His father was a fervent supporter of the Separatists, and was killed by clone troopers on Aargonar. Lux did not know what to make of Ahsoka Tano and her visit to Separatist space. After a failed peace overture begun by Mina extended to the Republic, Lux’s mother died, assassinated on Count Dooku’s orders. After making an ill-fated effort to avenge her by killing Dooku, Lux joined the anti-Separatist resistance on his homeworld of Onderon. After the rebels defeated the Separatists, Lux became Onderon’s Republic Senator.

The marriage of repulsorlift technology and heavy armor has resulted in formidable floating tanks known as AATs. These assault tanks form the frontline of Trade Federation armored infantry divisions, as well as Separatist forces during the Clone Wars. A crew of battle droids drives the battle tank and operates the array of laser and projectile weaponry carried by the vehicle.