"Darkness on Umbara" represents the seventh installment within the fourth season of the animated television program, Star Wars: The Clone Wars. Notably, this episode initiates a narrative arc spanning four parts, centered around a Jedi general about whom the clone troopers harbor reservations. Its original broadcast occurred on October 28, 2011.
Aboard their command ship, Anakin Skywalker and Obi-Wan Kenobi engage in a strategic discussion regarding their impending assault on the Umbaran capital, a city fortified by both Confederate and local militia forces. Joined by Rex and Fives, Anakin prepares to counter incoming enemy reinforcements targeting Obi-Wan's collaborative offensive alongside Jedi Masters Saesee Tiin and Pong Krell.
Braving intense anti-aircraft fire, the Republic AT-RT units neutralize the Umbaran tanks, facilitating the deployment of clone troopers via transports. However, the assault is complicated by the planet's naturally dim and foggy environment, as well as indigenous wildlife, one of which nearly ends the lives of Fives and Hardcase, but Fives eliminates it using a thermal detonator. As Anakin Skywalker and his clone troopers pause to prepare for their mission, the Umbarans launch a surprise attack, compelling them to retreat. An aerial strike led by Master Krell arrives just in time to save them, but Krell delivers a troubling message to Anakin: Anakin must return to Coruscant to meet with Supreme Chancellor Palpatine for reasons undisclosed. Despite his reluctance to abandon his troops during battle, Anakin ultimately relinquishes command to Master Krell and embarks on the journey to the Republic capital.
Immediately following Skywalker's departure, Krell adopts a dismissive and condescending attitude towards the clone troopers, displaying a lack of respect or consideration. His unwavering determination to complete the mission at any cost gradually provokes the clone troopers. Upon reaching the capital, Krell demands an alteration to the attack strategy, favoring a direct frontal assault on the capital's main thoroughfare instead of a series of preemptive surprise attacks against the enemy's defenses—a tactic that would expose them to significant enemy fire. As Rex had anticipated, the battalion encounters enemy traps, including mines on the main road and a comprehensive ambush that results in numerous trooper casualties. Rex orders a retreat to secure a more advantageous combat position. Although frustrated by the clones' withdrawal, Krell dispatches additional troopers and AT-RT drivers to rescue Rex and his men. After successfully repelling the native forces, Krell immediately reprimands Rex for retreating and disrupting his plans. Rex and Fives confront him, expressing their objections and emphasizing that, while they acknowledge the mission's importance, they are also concerned about their comrades' well-being. Krell offers Rex a backhanded compliment, but before Rex and Fives can fully process Krell's words, the Umbarans initiate a counterattack, forcing them to refocus on the ongoing battle.
Throughout the duration of the episode, General Krell consistently addresses Captain Rex as CT-7567, despite Rex holding the rank of captain and possessing the designation CC-7567, as documented by various sources. This error is repeated when Fives confronts General Krell, with Krell referring to Fives as ARC-5555, even though Fives' designation is CT-27-5555. Rex's Encyclopedia entry on StarWars.com subsequently confirmed his designation as CT-7567.
The scene depicting gunships delivering AT-RTs suggests that each gunship can only transport one AT-RT. However, later in the episode, approximately 10 AT-RTs engage in combat, indicating that more gunships were deployed than initially shown.
During the gunships' descent, six gunships are visible. One gunship is shot down, yet upon landing, six gunships are present once more.
In the scene where Krell first addresses Rex by his designation number, Krell's goatee is absent.