At the end of the Star Wars prequels, the Empire had a full army of clone troopers, but that army was eventually replaced with normal human Stormtroopers, and the impact of this is explored further in The Bad Batch and Obi-Wan Kenobi. In the wake of the Empire’s formation and the events of Order 66, Palpatine’s regime began a gradual expansion of centralized power throughout the galaxy, shifting the old systems of the Republic more and more towards a dictatorship. This process started during the events of The Bad Batch and continued up until the events of the original Star Wars trilogy, by which point the last remnants of the Republic were well and truly swept away.
The Jango Fett clones who comprised the Grand Army of the Republic were one of those remnants. Though the clone troopers served Palpatine’s purposes perfectly during the Clone Wars, they became a liability in peacetime for a few reasons. As seen in Obi-Wan Kenobi with a homeless Republic veteran begging on the street, the post-war period and early days of the Empire didn't end well for the clone army. The exact timeline of the Empire’s phasing out of clone troopers is different in Legends than in the Canon, but the root motivations remain the same.
Related: Star Wars: Every Type of Stormtrooper In Canon Explained
In the Legends timeline, the Empire conducted various experiments with cloning after the end of the Clone Wars, including some projects meant to create Force-sensitive soldiers. Clones served as high-level shock troopers and remained a significant military asset for years after the Republic’s dissolution, though eventually, they began to be replaced with ordinary recruits. The main motivation for the switch to Stormtroopers was simply that cloning
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