8 Star Wars Questions That Always Confused You

During the prequels, the clone troopers were introduced as the elite of the elite, modelled on the genetic template of one of the most feared bounty hunters in the galaxy, Jango Fett. They were superior to battle droids, trained by the finest military minds and mercenaries, and would obey the Emperor's every whim once the chip that contained Order 66 was activated. So, why were they phased out and replaced with humans shortly after the conclusion of the Clone Wars?

Clone troopers served as the first of the Empire's stormtroopers for a good few years following the Clone Wars, and were even recruited to assist Darth Vader's Inquisitors as they hunted down survivors of the Jedi Purge, utilising their familiar DC-15 heavy blasters in combat.

However, due in part to the accelerated ageing process that provided the Republic and then Empire with a regular supply of soldiers, it was soon decided that the clones should be phased out, with many ageing more rapidly than regular human cadets. The Empire also shutdown the cloning operation on Kamino, and by the time of the Original Trilogy, only a small number of clones remained in active service.

Because the Imperials were no longer incurring mass casualties, it made no sense to continue developing clones. (There's also the chance Palpatine wanted to tie-off a loose end in the Order 66 conspiracy, and that would've provided the perfect excuse.) Even so, the Empire continued to use the clones' service during the Republic era as propaganda to recruit human soldiers, even as some troopers began to question their actions during the Jedi Purge.