Battle of Umbara The battle of Umbara took place during the Clone Wars on the planet Umbara . It was also the event during which the treason of Jedi General Pong Krell was revealed , whose ultimate goal was recognition by Count Dooku to become his new apprentice . Prelude . The Separatists started to tighten their grip over vital and isolated supply routes . Following the death of Umbara ' s senator , Mee Deechi , the Umbarans withdrew from the Republic and committed their militia to the Confederacy of Independent Systems . The Republic then sent Jedi Master Pong Krell , Jedi Knight Anakin Skywalker and Jedi Council members Obi - Wan Kenobi and Saesee Tiin to retake Umbara with their troops . The Battle . Northern landing . Spearheaded by Z - 95 Headhunter s of the 327th star corps led by Jedi Commander s Ahsoka Tano and Barriss Offee , the Republic forces broke through the Separatist blockade . As they made their landing Kenobi spoke to Skywalker , Cody , Rex and their troops to discuss their strategy . Masters Krell ' s and Tiin ' s troops would be supporting Kenobi ' s 212th Attack Battalion in the south , while Skywalker ' s 501st Legion would come in from the north , and take out enemy reinforcements . The main objective was to conquer the capital as quickly as possible and hold it . As the " Acclamator " - class transgalactic military assault ship entered the atmosphere , the ground forces were deployed in gunships protected by the Headhunters . The gunships also deployed numerous AT - RTs that were able to charge the Umbaran Militia ' s hover tanks and destroy them . Skywalker ' s troops then landed and moved towards a ridge , fighting the Umbarans and forcing them to retreat . However , one of troopers , Hardcase , was almost eaten by a Vixus . Hardcase was then saved by ARC Trooper Fives . At the ridge , the clones then entrenched themselves . However , the Umbarans ambushed them by using a Millicreep droid to distract them . The Umbarans then circled around the clones ' encampment . Skywalker then called in Odd Ball to bombard the area with Y - wings to wipe out the Umbarans . As Skywalker forces regrouped for the attack on the Capital , Master Krell arrived with orders from the Jedi Council ordering him to return to Coruscant at the Supreme Chancellor ' s request . Skywalker reluctantly followed the orders and command of the 501st went to Krell . Krell then ordered the 501st to march onward towards the capital . En route , the clones came under attack by a pair of Banshees . They then resumed the march after Krell killed the last one . When the 501st reached the outskirts of the capital , Krell decided to launch a full forward assault on the capital along the main road , despite Rex ' s objections . However , they walked into a Mine field , that killed Oz and Ringo . Fives was then able to find a way through the field . The 501st then came under attack by the Umbarans , holding their ground despite being exposed . Rex then ordered a retreat to rejoin Krell and his troops . Together , they were able repel the Umbarans . Krell was disappointed at Rex for not holding the road , but was convinced that Rex and Fives did what was best for their men . Rex and the 501st then fought the Umbarans counterattack . Capturing the airbase . Krell , Rex , and the 501st continued to hold their ground against the Umbarans from both their air and ground forces . Krell was then contacted by Kenobi , who ordered him and the 501st to capture the airbase . The airbase was supplying the capital with supplies that prevented the 212th from taking the capital . The 501st then regrouped and moved towards the airbase . As the 501st reached the outskirts of the airbase , Rex suggested that they scout the area first . Krell , knowing the urgency of Kenobi ' s situation , ordered the 501st to go through a gorge single file . The 501st troopers started to criticize Krell ' s tactics knowing they would suffer heavy casualties . Despite , Rex was able to convince the 501st to go ahead with the attack . As the 501st entered the gorge , Rex divided it into three groups with Fives and Hardcase . As they made their way through , they came under attack by caterpillar tanks . However , they were able to destroy the tanks with their rocket launchers and Thermal detonator s . They resumed moving towards the airbase , until they came under fire by the Umbarans ' MHCs . Rex and the 501st attempted to use the rocket launchers against the MHCs to no avail . Rex then sent Fives and Hardcase to infiltrate the airbase and commandeer a pair of Zenuas 33 Umbaran starfighter s to use against the MHCs . Krell , however , ordered Rex to launch a full - scale attack . Rex and his men the continue to hold their ground against the MHCs . Fives and Hardcase were able to pass the sensor fence by using a tree . After Fives blew up the tree to distract the Umbarans , he and Hardcase were able to board a pair of starfighters and used them to destroy the MHCs . Krell and Sergeant Appo and brought in the rest of the 501st and took the airbase . The 501st then rounded up the remaining Umbarans as prisoners and held the base before moving on to taking the capital with Kenobi . Attack on the Supply Ship . After securing the airbase for the Republic , the Umbarans stepped up their attacks in their attempts to retake the airbase . Krell and 501st made sure security measures were reconfigured and that all the troopers stayed on alert for anything . During this time , Fives was examining the Umbaran starfighters . Krell was then contacted by Kenobi , who congratulated him on taking the airbase , despite Krell wanting to wait until the battle was won . Kenobi told Krell that the 212th was being pushed away from the capital by long - range missiles . The capital was now receiving supplies from a Separatist supply ship protected by a Separatist fleet that outnumbered the Republic ' s fleet . Krell stated that they would have take the capital , regardless of the missiles and would meet up with Kenobi and 212th at the rendezvous point . Kenobi ' s transmission was then lost . Despite this , Krell ordered the 501st to be prepared in twelve hours to advance to the capital ; Rex then asked Krell if he should try to get a message to Kenobi in order to coordinate the attack . Krell , however , knew Kenobi had his hands full and asserted that they need to throw everything they had at the capital . Despite Rex claiming they would walk into a blast zone , Krell disagreed with him and ordered him to prepare the 501st . After Rex briefed his troops , Fives told him that he had broken Umbaran access codes and that they could use the captured starfighters to infiltrate the supply ship and destroy it . Rex presented the idea to Krell , who shot it down immediately . Fives disobeyed Krell , along with Jesse and Hardcase and preceded with the mission . The three embarked on their mission with the starfighters . The plan was working until a droid spotted Hardcase in one of the ships . The tactical droid in charge ordered the droids to put the rayshields up to defend the ship ' s core systems . The droids did so which resulted in the clones being cornered . The troops fought back until Hardcase set his ship down . He detached a part of the ship and used it to blow up the ship , sacrificing himself in the process . Betrayal of General Krell . Jesse and Fives were then sentenced to being court - martialed . Krell changed his mind from court - martialing the soldiers to sentencing them to execution . Fives and Jesse were led by Appo and other troopers to their execution . Dogma was in charge of leading the execution , the line of which consisted of Kix , Tup and several other troopers . Fives appealed to his brothers , which resulted in the soldiers dropping their weapons . Krell , outraged , ordered Rex and Dogma to his tower . Before Rex and Krell could argue over the matter , the tower received a transmission from a clone scout , informing them that the Umbarans were preparing another offensive , possibly with the aid of clone armor and weapons captured from a platoon . Krell decided on a preemptive strike . The troops moved out , but soon ran into a firefight and began targeting what they believed to be the enemy in disguise . The transmission was fake , which resulted in the 212th Attack Battalion and 501st Legion attacking one another . Rex saved the remainder of their forces by removing the helmet of a fallen 212th trooper . After the battle , Kix had discovered the 212th platoon leader , Waxer , mortally wounded . Waxer revealed that it was Krell who gave the order before his death . Rex gathered the remaining survivors of the 501st and the 212th to capture Krell . Dogma initially accepted this and wanted justice for his fallen brothers . However , due to him being a " loyal " soldier , he stepped out of the coup . The group of soldiers entered the control tower , in which Krell was alone . The 212th and 501st surrounded him , and Rex told Krell that he was being " relieved of duty " . Krell , angered , Force pushed all the clones back and killed several of the 501st and 212th present in the room . When pursuing the traitor , Rex , Jesse , Fives , and the others were stopped by Dogma , who was then arrested . The troopers followed Krell into the forest of Umbara , before Krell attacked . He killed several clones , flinging Tup up several meters until he hit a Vixus , which awoke briefly . Tup then contacted Rex to lure the general towards him . The remaining soldiers retreated towards Tup who opened fire on the general . Krell rushed him , but then stepped on a limb of the Vixus , which grabbed Krell . Krell was flung helplessly through the air until he detached the Vixus ' tongue and arm that was grasping him . Krell dropped to the ground , and watched as the clones killed the Vixus . He attempted to escape , but Tup stunned him , thus ending the conflict . It was later learned by the troopers that Kenobi ' s 212th Attack Battalion had spearheaded and captured the Umbaran Capital earlier that day .