War in the Expansion Region! As the Separatists tighten their grip over vital but isolated supply routes, the Republic launches a lightning strike into the remote Ghost Nebula to control the strategic system of Umbara. Republic forces smash through the Separatists in an effort to claim the shadowy world.

Aboard a Jedi transport, Obi-Wan Kenobi outlines the attack strategy. Jedi Masters Krell and Tiin will be supporting his troops in the south as he leads an assault to capture the capital of Umbara. Anakin will command the 501st battalion from the north, taking out local militia reinforcements to ensure they cannot protect the capital.

The assault begins! Republic gunships outfitted with piercing spotlights plunge into the thick, obscuring fog of Umbara. Swift Headhunter starfighters zip ahead of them, offering escort through the surface cannon-fire. Clone pilot Hawk flies the gunship that carries Anakin Skywalker and Clone Captain Rex.

Rex checks on his team. Tup, a young clone, is hanging in there. Hardcase, a gun-happy veteran, is eager to take the fight to the Separatists.

The gunships fly low over the terrain, depositing AT-RT walkers onto the battlefield. The clone cavalry charges into battle on their swift-footed scouts.

Their enemies are the Umbaran militia. In many ways, the technology the Umbarans possess is more advanced than that found in most of the galaxy. These high-tech locals open fire with heavy artillery.

With the landing zone secured by the AT-RTs, the gunships stop and open their bay doors. The clone troopers leap out onto the murky plains. General Anakin Skywalker leads the charge from the frontlines. Their first target: a nearby ridge that can be converted into a staging area.

As they march their way through the gloom, troopers Tup and Hardcase nearly trip over what appears to be a thick, ropey vine. It's the tentacle of a hungry creature: a terrifying vixus. The stationary beast opens its sharp-toothed maw and flails its tentacles, as it draws an ensnared clone trooper into its mouth. ARC trooper Fives is nearly dragged in, but throws an armed thermal detonator into the monster's mouth.

The 501st secure the ridge and plan their next move. General Kenobi's battalion is pushing towards the capital. Anakin orders his troops to get what rest they can. Skywalker and Rex briefly exchange some light-hearted observations on the eagerness of some of the new generation clones, like trooper Dogma.

Suddenly, Umbaran soldiers launch an attack. The clone troopers are caught off-guard. As they hold off their attackers, Rex radios in an airstrike and leads his troops to take cover south of the ridge. A pair of Y-wing fighters led by Oddball, spared from General Krell's assault, streak in overhead and carpet-bomb the Umbaran positions.

A gunship lands, and a brawny, Besalisk Jedi General emerges: Pong Krell. Krell announces that Anakin has been ordered by the Supreme Chancellor and the Jedi Council to return to Coruscant. Command of the 501st will fall to Krell in the interim. Anakin hates leaving his men in the middle of a mission, but Rex assures him the mission will be in good hands.

Krell immediately makes it clear that his command is of a different style and temperament than Anakin's. He is a hard leader, but an effective commander, and observes military protocol above all else. Krell orders the troopers to move out immediately and march through the hills.

Krell's grueling orders force the 501st to march overland for 12 hours straight. Rex asks the general to allow his men some rest, but Krell will not have it. Calling Rex by his CT number rather than by his name, Krell stresses that the comfort of the clones is not as important as capturing the capital. The other battalions are counting on their success.

As the 501st make their way up the jungle road, Krell lays out his attack plan to Rex. He is altering General Skywalker's strategy. Rather than spread the battalion out to launch a series of surgical strikes against the city, Krell is organizing the troops into a single, full-frontal assault. Rex thinks this is misguided, as they do not know the extent of the capital's defenses. Krell will not have his orders questioned.

The troops are wary of General Krell's tactics. Fives and Tup find it reckless. Dogma defends Krell, while Hardcase is simply focused on bringing the fight to the enemy. Fives knows that Rex disagrees with the strategy, but Rex points out that now is not the time for debate.

The jungle road is mined. Troopers Ringo and Oz die in an explosion, and Umbarans waiting in the jungle launch a devastating ambush. The troops in Rex's platoon are exposed. He orders his troops to pull back and seek cover.

Krell is furious that Rex has pulled back from the road and ceded control of this path to the Umbarans. Angry, Fives points out that Rex saved the platoon. Krell ignites his lightsaber, and orders Fives to stand down. Rex holds his ground, stating he followed flawed orders that cost the lives of men, and his duty is to protect his men. Krell takes note of Rex's opinion, and dismisses him.

The tension of that confrontation immediately dissipates in the face of a greater danger. The Umbarans continue their assault. The clones hold their ground. The battle goes on....