The Citadel " The Citadel " is the eighteenth episode of the ' . It aired on February 18 , 2011 . Official description . " " With help from R2 - D2 and a squad of captured battle droid s , an elite team of Jedi and clone trooper s led by Obi - Wan and Anakin attempt to free a captive Jedi General , Even Piell , from an impenetrable prison . Despite orders to the contrary , Ahsoka Tano tags along , though she proves indispensable when the infiltration mission begins to evolve . Piell and his fleet officer , Captain Tarkin , are liberated from their cells , but now the fugitives must escape the Citadel itself . " " Plot summary . At the Jedi Temple on Coruscant , Master Plo Koon briefs Obi - Wan Kenobi , Anakin Skywalker and their team - which includes Commander Cody , Captain Rex , and recently promoted ARC troopers Echo and Fives - on their newest mission : to infiltrate the " impenetrable " Citadel on the Separatist planet Lola Sayu to free Master Even Piell before the droids force him to give up the coordinates of the Nexus Route . Unfortunately , the information on the Citadel they have retrieved from the Jedi Archives is long since outdated , and no new intelligence could be gathered since the Citadel is specifically designed to hold high - level prisoners , especially Jedi . The plan incorporates a plot devised by Anakin using reprogrammed battle droids led by R2 - D2 to pilot a Class type B escort shuttle through the orbital defense lines , and the human and clone crew being frozen in carbonite to fool life form detectors . However , Anakin ' s Padawan Ahsoka Tano chafes at being left behind , since her master has insisted that this mission would be too dangerous for her , and even her complaint to her old friend Master Koon yields little comfort . After the strike team is carbon - frozen , they are loaded onto the shuttle and transported to the Citadel . When the droid ' s ship reaches orbit above Lola Sayu , they are interrogated about their cargo by the Citadel ' s warden , Osi Sobeck , and his tactical droid , K2 - B4 . The ship and its cargo pass the scans , and land in a cavern near the Citadel , where the droids unload and thaw out the strike team . To their consternation , Anakin and Obi - Wan discover that Ahsoka has also had herself frozen and smuggled into the group , claiming that she is acting under orders of Master Koon . Now unable to turn her away , they decide to let her join in . The first hazard comes in form of a cliff wall blasted by a strong gale and littered with electromine s , which prevent the use of jetpacks and grappling cables . The cliff is the only way to a small side door , which is , however , patrolled regularly and otherwise secured by a ray shield . Ahsoka proves her usefulness to the team when she manages to slip inside through a ventilation port and deactivates the shield from within , but as the rest of the team ascends , clone trooper Charger looses his balance , falls down the cliff and sets off a mine , alerting Sobeck that the Jedi have infiltrated the Citadel , and the alert is sounded . As the team makes its way through the hall , it encounters many booby traps , such as wall laser guns and an moving electrified wall which leads to the death of another trooper . They find and save Master Piell before he can be tortured by a droid interrogator . However , the Jedi learn that while Master Piell has managed to erase the Nexus coordinates from his ship ' s databanks , he has decided to memorize them by half , with the other part having been entrusted to his captain . While the officers are being kept in a cell further inside the Citadel , Piell was forced to surrender his part of the code , therefore necessitating the liberation of the fleet captain to keep the Nexus Route safe . Anakin , Ahsoka , Obi - Wan , Piell and the rest of the team then head down to the other cells , just before they are ambushed by commando droids . Sobeck activates a magnetic ceiling which takes the team ' s weapons and Anakin by his bionic hand . Obi - Wan , Piell and Ahsoka try using the Force to subdue the commando droids , but the commando droids have magnetized feet plates and are merely kept off - balance . Despite Sobeck electrocuting him , Anakin manages to reach his lightsaber and disable the magnets , enabling the others to retrieve their weapons . The Jedi and their team then find Piell ' s officer , Captain Wilhuff Tarkin , and the other officers . Obi - Wan and Anakin decide to split up the team , with Obi - Wan , Cody and Piell creating a diversion while Anakin , Ahsoka , Rex , Echo and Fives take Tarkin to safety . Tarkin argues to continue as one team for the advantage in numbers , but Master Piell agrees with Kenobi , and so Obi - Wan ' s team sets off . Anakin cuts a hole into a wall which opens into a cavern system which were included in the scant information from the Jedi archives . Although Tarkin remains highly skeptical of this plan and openly voices his criticism , Anakin is determined to carry on . Behind the scenes . The carbon freezing plot was previously employed in the " " . However , since Skywalker remarks that this is " the first time " this tactic was applied in the episode , this introduces a continuity error , as the events of " Shipyards " took place sometime before the episode . However , this contradiction was removed when the graphic novella was put into the Legends continuity in 2014 .