Darkness on Umbara

"When Anakin is forced to temporarily turn over command of his clone troopers to a new commander, the Jedi Pong Krell, tensions begin to run high as the clones are assigned with a very deadly mission to take the capital of Umbara."

Aboard their command ship, Anakin Skywalker and Obi-Wan Kenobi discuss their attack strategy against the Umbaran capital city, which is defended by both Confederate and local militia forces. Joined by Rex and Fives, Anakin prepares to repel enemy reinforcements striking against Obi-Wan's joint attack with Jedi Masters Saesee Tiin and Pong Krell.

Amidst heavy flak fire, the Republic AT-RT forces take out the Umbaran tanks, allowing the transports to set down their load of clone troopers. But the assault is hampered by the planet's natural murkiness and foggy conditions, as well as the local wildlife, one of which nearly claims the lives of Fives and Hardcase, though Fives kills it with a thermal detonator. When Anakin Skywalker and his clones take a break before preparing for their mission, the Umbarans execute a sneak attack, forcing them to retreat. An airstrike by Master Krell saves them just in time, but Krell approaches Anakin with a disconcerting message: Anakin is to return to Coruscant and meet with Supreme Chancellor Palpatine, for reasons unknown. Reluctant to leave his troops in the midst of battle, Anakin nevertheless relinquishes command over his troops to Master Krell and makes the journey to the Republic capital.

As soon as Skywalker departs, Krell adopts a very derisive, condescending stance towards the clone troopers, showing them no respect or consideration. His harsh determination to complete the mission at all costs gradually raises the ire of the clone troopers. When they reach the capital, Krell insists on a change in the attack plan, opting on a full frontal assault on the capital's main road instead of a series of preemptive surprise attacks against the enemy's defenses—a course which would expose them to heavy enemy attack—and, as Rex feared, the battalion begins to run into enemy traps, with mines on the main road and an all-out ambush which claims the lives of many troopers. Rex orders his troopers to retreat in order to attain a more advantageous fighting position. Though frustrated by the clones' retreat, Krell ordered additional troopers and AT-RT drivers to save Rex and his men. After they repel the natives, Krell immediately criticizes Rex for retreating and compromising his plans. Rex and Fives stand up to him, voicing their protests and pointing out that, while they are aware of the importance of their mission, they are also concerned about the welfare of their men. Krell eventually gives Rex a dubious compliment, but before Rex and Fives have the time to contemplate Krell's words more thoroughly, the Umbarans launch a counterattack, forcing them to refocus on the battle.

Throughout the episode, when General Krell addresses Captain Rex, he refers to him as CT-7567, even though Rex is a captain and holds the designation CC-7567, per many sources. This same mistake is made when Fives stands up to General Krell, in which Krell addresses Fives as ARC-5555, though Fives holds the designation CT-27-5555. Rex's Encyclopedia entry on StarWars.com later confirmed that his new designation is CT-7567.

The scene where the gunships are delivering AT-RTs shows that a gunship can only carry one AT-RT. However, later about 10 AT-RTs charge into battle, proving more gunships were deployed than were seen.

When the gunships are descending, there are six gunships. One gunship gets shot down, but when the gunships land, there are six again.

During the scene where Krell first addresses Rex by his designation number, Krell's goatee is missing.