The Cuis clones were six prototype clone stormtroopers, bred from the genome of Sa Cuis, a Dark Jedi who served as one of Emperor Palpatine's personal assassins. Through their progenitor, they gained a strong connection to the Force, thus making them a unique batch compared to the rest of the soldiers in the Stormtrooper Corps, all of whom were cloned from the templates of ordinary Humans at the time. Their creation and training were closely monitored by the Emperor and his apprentice, the Sith Lord Darth Vader, as part of an experiment to create a battalion of obedient clone soldiers trained in the ways of the dark side of the Force. In addition to his connection to the Force, Cuis was chosen as a template by Vader because of his sense of loyalty—a trait that the Dark Lord hoped the clones would inherit from the deceased Dark Jedi.
A Cuis clone's lightsaber hilt
In the months following the birth of Emperor Palpatine's New Order in 19 BBY, the Sith Lord Darth Vader authorized an experiment to clone the genetic code of a Force-sensitive template. Instead of relying on the Kaminoan method that created the Republic Grand Army, the Dark Lord of the Sith entrusted the project to the Clone Masters of Arkanian Microtechnologies, a company known for their use of Spaarti cloning cylinders. The genome itself was the Dark Jedi Sa Cuis, an Emperor's Hand who attempted to assassinate Vader—as part of the Sith Lord's training—on Palpatine's order. Impressed by the Hand's fighting skills and Force abilities, Vader captured Cuis after defeating him in combat. When his Arkanian scientists collected enough genetic samples from Cuis for replication purposes, Vader decapitated his prisoner.
Prior to his death, Cuis refused to admit that the one who ordered the Dark Lord's death was Vader's own master, although Vader had already deduced that Palpatine sent Cuis to kill him as a test in his training. Far from being vexed by Cuis's lack of cooperation, Vader respected his clear sense of duty as an Emperor's Hand, something Cuis had been unwilling to break even with the promise of being spared from execution. It was his hope that the clones of Sa Cuis would not only retain their progenitor's connection to the Force, but also his other qualities such as loyalty and courage.
A Cuis clone demonstrates his skills in lightsaber combat against Darth Vader.
After more than a year of replicating the Cuis genome, Arkanian Microtechnologies had produced six prototype clones of Sa Cuis, fully grown and trained as Imperial stormtroopers. Although they wore the same standard armor as the clone infantry units of the Stormtrooper Corps, the Cuis clones were armed with a red-bladed lightsaber instead of the E-11 blaster rifle. In addition to their skills in melee combat, the clones also learned to harness their inherited Force powers, enabling them to utilize telekinetic techniques. After their maturation stage was completed, the Cuis clones received their training in an Imperial training center located on the planet Yinchorr. Both Emperor Palpatine and Darth Vader closely monitored the development of the Cuis clones, but most of their practical instruction was handled by another Hand named Sheyvan.
The two Sith Lords personally oversaw the Cuis clones during the final stage of their trials. They demonstrated their lightsaber skills against each other, as well as Darth Vader, while the Emperor observed their performance. The final test in their training was a match that pitted each of the six Cuis clones against a clone of Lieutenant Erv Lekauf, one of Vader's most trusted officers. The Cuis clones were disarmed of their lightsabers given that the contest was a non-lethal exercise, although they quickly proved that their Force abilities were more than sufficient in defeating the clones of an ordinary template. The Emperor was sufficiently pleased with the results of his new Force-sensitive stormtroopers and instructed Vader to place an order with the Arkanians for an entire battalion of Cuis clones. As the Sith Lords departed Yinchorr for Imperial Center, the Cuis clones accompanied them as the newest members of Darth Vader's 501st Legion.
Sheyvan, leader of the Cuis clones, attacks Darth Vader.
While Palpatine and Darth Vader speculated on the advantages of cloning an entire army from the Cuis template during their return to the Imperial capital, Sheyvan rebelled against the Emperor, revealing the traitorous intentions he had been harboring since his discovery of Palpatine's other Hand, Sa Cuis. Now aware that he was not the only Dark Jedi assassin in the Emperor's employ as he had been led to believe, Sheyvan felt that his loyalty had been repaid with deception. In his time as the personal trainer of the Cuis clones, the Hand secretly co-opted their allegiance, ensuring that they would fight for the one who trained them, rather than the two Sith Lords that merely commissioned their creation.
Their insurrection came as a great surprise to the Imperials; with the exception of the Emperor, whom Vader observed to be suspiciously calm given the situation, all of the personnel aboard Palpatine's Lambda-class T-4a shuttle were caught completely off guard and were unable to prevent the Cuis clones from seizing control of much of the vessel. Yet despite their demonstrated superior skills against non-Force-wielders, both during training exercises and Sheyvan's rebellion, none of the Cuis clones were able to defeat Vader in combat. The Dark Lord, with the aid of Lekauf's clone stormtroopers, engaged the ex-Hand and Cuis's clones in combat. Armed with flamethrowers, the Lekauf clones burned four Cuis clones; the remaining two were Force choked by Vader. Sheyvan fought Vader alone in a brief duel, but was ultimately killed when he was cut in half from shoulder to hip. Afterward, Vader and Palpatine had the Sa Cuis template decommissioned, although the latter remained open to the possibility of cloning a Force-sensitive army in the future.
Because of the Cuis clones' part in Sheyvan's treachery, Darth Vader became staunchly opposed to further use of the Cuis line, as well as any Forceful template. The failed insurrection, however brief, convinced him that Force-sensitives—and even clones of Force-sensitives—were naturally inclined to secure greater power through betrayal of their masters, especially if they relied on the dark side of the Force. As such, he chose to restrict clone lines to ordinary candidates; the Stormtrooper Corps continued its use of clone soldiers, but none after the Cuis clones were engineered from a Forceful genome.
Though Vader had long since abandoned the concept of "Force-sensitive stormtroopers," he was forced to reconsider his position against cloning a Forceful template after the untimely death of his former apprentice, the pseudo Sith-turned-Jedi Galen Marek. Using the apprentice's preserved corpse as a template in the Timira City Cloning Facility on Kamino, Vader conducted an experiment to create the perfect clone of his fallen disciple—a more powerful and obedient version of the original Starkiller. Unlike the success Vader had enjoyed with creating stable clones from the Cuis line, the Marek template proved almost impossible to replicate without encountering a myriad of setbacks, forcing Vader to repeat the procedure numerous times in an attempt to gradually correct the errors in the experiment. Scientists were perplexed in trying to understand why there was such an inherent difficulty in cloning a Forceful being, although a few experts—such as Ni-Ke-Vanz, a Rebel medic—speculated that the Force was somehow responsible for undermining the stability of clones created from genetic donors with high concentrations of midi-chlorians in their cells.
The genetic flaws aside, the Marek clones differed from their Cuis precursors in another way—they were all trained by memory flashes, enabling them to inherit their donor's skills, but also Marek's emotional attachments that Vader held responsible for weakening his former apprentice. With the exception of a lone test subject, every clone of Marek was unable to differentiate his own thoughts and memories from those that belonged to their progenitor, leading to cases of identity crises and ultimately insanity.
Original concept art of lightsaber-wielding stormtroopers
In the commentaries for the Special Edition, George Lucas notes that in his early conceptions of the saga, lightsabers were commonplace weapons throughout the galaxy, but that he later decided that they should be limited to the Jedi. Based on Lucas' original conception, Ralph McQuarrie created concept art of lightsaber-wielding stormtroopers for A New Hope. This was referenced in the image above in the pose of the stormtrooper to the right of Darth Vader.
- The Complete Star Wars Encyclopedia