The Confederacy of Independent Systems, also known as the Separatist Alliance, was a collection of star systems and corporate titans that left the Republic and fought for independence against the Republic’s clone armies and Jedi Knights. The charismatic former Jedi Count Dooku was the Alliance’s political leader, while its military power came from credits and assets donated by powerful galactic trade groups. No one suspected that the Alliance was actually a tool of Darth Sidious, who had engineered the Clone Wars as part of a Sith plot to rule the galaxy.

Umbara, known as the "Shadow World" due to the rays of its sun never completely reaching its surface, is perpetually dark. The native wildlife have adapted to survive in such gloom, making the planet perpetually dangerous. Umbara was once part of the Galactic Republic, represented in the Senate by Senator Mee Deechi. Later in the Clone Wars, the planet's loyalty wavered and the natives of Umbara allied themselves with the Separatists, bringing their extremely advanced technology to the Separatist Alliance.

Also known as CT-27-5555, Fives trained with Domino Squad on Kamino before being shipped out to the Rishi Moon listening outpost. He survived the Separatist attack on the station there, and was transferred to the 501st Legion alongside his squadmate and fellow survivor, Echo. Fives and Echo were promoted to ARC trooper status after the defense of Kamino from Separatist invaders. He and Echo were later assigned with the difficult mission of freeing Republic prisoners from the daunting Citadel prison installation on Lola Sayu. He and Echo were later part of a mission to free Republic prisoners from the Separatist prison called the Citadel. Echo fell in battle, leaving Fives as Domino Squad’s sole survivor. Fives accompanied the clone trooper Tup to Kamino for medical testing, where he discovered a terrifying secret about the clones’ origins and ultimate purpose.

The clone troopers of the 501st Legion are a tight-knit bunch, loyal to the end to their Jedi General, Anakin Skywalker. Jesse was a hard-fighting patriot who proudly wore the cog-shaped symbol of the Galactic Republic on his helmet, and as a large tattoo that covered his face.

"Let me at 'em!" was Hardcase's typical reaction when presented with enemy forces, no matter how overwhelming the odds. Legend has it that his growth chamber sprung a leak during his formation on Kamino, resulting in his characteristic, somewhat aberrant, but nonetheless useful hyperactivity. When the blaster bolts fly, Hardcase loses all sense of self-preservation and returns fire with zeal, determined to wipe out the enemy with repeated sweeps of his rotary laser cannon.

Using the highly advanced technology native to its planet of development, the Umbaran starfighter is the most intuitively-designed ship in the galaxy. Its shielded cockpit surrounded the pilot with touch-sensitive holographic displays that react instantly to touch. The ship's unique construction allows its airframe to flex and bend, not only adding to its maneuverability, but allowing it to land and take off with a minimal of mechanical effort. It boasts the energetic plasma weapons found on many Umbaran craft, as well as modular missile pods.