The Umbaran militia served as the primary defense organization for Umbara, a planet shrouded in mystery situated within the Ghost Nebula. The native Umbaran population formed the ranks of this militia, leveraging advanced technology developed on their homeworld to both protect their territory and engage opposing forces. Beyond the soldiers functioning as standard infantry, the militia also deployed millicreep assassin droids, formidable hover tanks, multi-legged assault tanks, and enormous, mobile heavy cannons. Furthermore, the Umbarans utilized specialized air defense platforms, most notably their technologically distinctive starfighters and combat support ships.
During the period of the Clone Wars, the Umbaran militia fought against the forces of the Galactic Republic, supporting their planet's secession and alignment with the Confederacy of Independent Systems. Despite initial expectations from the Grand Army of the Republic's Jedi Generals for a swift resolution, the Umbaran militia demonstrated unexpected resilience and resourcefulness. The Umbarans inflicted significant losses on the enemy's clone trooper forces, but were eventually compelled to retreat towards the capital city of Umbara. Following the 501st Legion's capture of a critical militia airbase, High Jedi General Obi-Wan Kenobi launched an offensive on the capital, seizing control from the Umbaran defenders. Despite receiving clandestine aid from the renegade Jedi Master Pong Krell, the militia suffered a decisive defeat near the captured airbase, effectively ending the conflict on Umbara.
The Umbaran Militia stood out due to their use of highly sophisticated weaponry, largely unseen beyond the borders of Umbara. Examples include millicreep droids and Umbaran blaster rifles. The body armor worn by the militia's soldiers was also remarkably advanced. This armor incorporated a pressurized mixture of chemicals in the form of a potent, performance-enhancing gas that amplified aggression, reaction time, and situational awareness. This gas was produced by filtering specific chemicals from the surrounding atmosphere through the suit, which then delivered the gas to the helmet for inhalation. However, these advantages came at a steep price: any breach of the suit's visor would cause a rapid pressure change, drawing out the oxygen mixed with the gases and leading to the soldier's asphyxiation, often resulting in death.
The Umbaran Militia deployed a diverse array of vehicles to inflict damage on the clone army. This included Umbaran hover tanks, technologically-advanced starfighters, Impeding Assault Tanks, Umbaran Mobile Heavy Cannons, and Umbaran Support Ships. A significant feature of many of these vehicles was ray-shielding, which made them exceptionally difficult to destroy. These vehicles were equipped with electric and plasma-based weaponry. The ground vehicles were capable of using their large, mechanical feet to crush clones underfoot.