The Battle of Umbara took place during the Clone Wars on the planet Umbara, during the year 21 BBY, the native species of the planet known as the Shadow People withdrew from the Galactic Republic following the murder of their ambassador on the Galactic Senate, Mee Deechi. Fearing the complete loss of the Umbaran system to the Separatist, the forces of the Galactic Republic led by Generals Obi-Wan Kenobi, Anakin Skywalker, and Saesee Tiin, engage both the Confederacy Of Independent Systems and the Umbaran supporters on the planet. After an air-to-ground assault and afterwards landing on the shadowy world, the Grand Army Of The Republic forces of Clone troopers established a foothold on the Umbaran soil and prepared for a massive invasion of the capital city. For this portion of the battle, General Skywalker was replaced by the revered and somewhat infamous Jedi, Pong Krell. However, the Republic forces were ignorant to General Krell’s obsessive personality, which led him to sabotage the Republic’s war efforts for personal gain.
Kenobi led the 212th Attack Battalion as the main attack force against the Umbara capital city, while Krell “led” the 501st Legion with Captain Rex to capture an airbase as preparation for the assault on the capital city, encountering heavy resistance from the humanoid Umbarans while trekking across the treacherous Umbaran landscape, full of dangerous wildlife and scattered with minefields. Displaying his brash and strict style, Krell often ordered his men to push on despite the overwhelming odds against them, which in reality was an effort to cause as many clone casualties as possible. Despite their misleading under Krell, the clone forces persevered and captured the airbase, due in part to a stealthy infiltration by Fives and Hardcase, who acquired two Umbaran starfighters to use as air support. An unauthorised strike against the Separatist fleet was launched from the newly converted airbase by the clones Jesse, Hardcasem and Fives using the stolen Umbaran starfighters. They successfully destroyed one of the main Separatist supply ships at the cost of Hardcase’s life.
After Rex and his men refused to execute the “defective” clones, Krell displayed his true colours by purposely leading the forces of the 212th Attack Battalion and the 401st against each other, resulting in many clones lost to friendly fire, including Waxer. The survivors of the ordeal came to the realisation that Krells was unfit for military command and resorted to arrest the rogue Jedi. Upon confronting Krell in his converted command tower in the airbase. Krell accused the clones of treason before attacking them with both of his double-bladed lightsabers and jumping out of the tower, fleeing into the Umbaran jungle. Rex and his men pursued, and were picked off one by one by Krell, who was using the jungle’s foliage for hiding. The young and idealistic clone Tup tricked the General into tripping over the appendage of the native stationary vixus beast which promptly attacked the disoriented Krell. The rogue general was then subdued and taken back to the airbase as a prisoner, where he was executed by the clone Dogma for his crimes against the Republic. Shortly after, the capital city was taken by General Kenobi and the 212 Attack Battalion, ensuring victory for the Republic forces and ending the battle on Umbara.