Star Wars has finally revealed how Emperor Palpatine hid his existence from Luke Skywalker. The Emperor's return in Star Wars: The Rise of Skywalker shocked the galaxy, but the seeds were sown in Chuck Wendig's "Aftermath" trilogy.

This book revealed Palpatine had established secret bases across the galaxy, so-called "Observatories" that were dedicated to specific purposes, and some served as treasure houses for the Emperor's vast collection of Sith artifacts. He begun constructing these shortly after rising to the role of Supreme Chancellor in Star Wars: Episode I - The Phantom Menace, and it's likely Anakin Skywalker stumbled upon one such installation on Mustafar in The Clone Wars. These were staffed with loyal droids, their identities restrained and subsumed to Palpatine's will, or with some of Palpatine's most devoted Imperial fanatics. But how did this network remain a secret after Palpatine's death in Return of the Jedi?

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According to the Shattered Empire miniseries, Luke Skywalker stumbled upon one of Palpatine's secret facilities shortly after the destruction of the Second Death Star. This facility was devoted to the mass-production of so-called Sentinel droids, who the Emperor intended to use to convey his last instructions to the galaxy. Fortunately for Palpatine, although one installation devoted to making the Sentinels was disrupted, it was too late. An unknown number of Sentinel droids spread across the galaxy, and they began attempting to conceal the existence of Palpatine's hidden network.

Star Wars Sentinel Droid Palpatine

The Sentinels commanded Palpatine's most loyal Imperials to commence Operation Cinder, envisioned as an act of retribution on the galaxy. This was a horrific scorched-earth policy, with Imperial Star Destroyers launched devastating attacks on countless worlds. Operation Cinder was designed to escalate the galactic conflict to a genocidal level not seen since the height of the Clone Wars, but according to Alexander Freed's recent book Shadow Fall it served another purpose. The Empire unknowingly targeted worlds where Palpatine had hidden his mysterious bases, destroying all record of their existence.

Operation Cinder was not entirely successful. It culminated in a battle over the skies of Jakku, itself site of an Observatory that Palpatine had used to map the Unknown Regions. The Emperor had transformed the planet into a bomb of stellar proportions, and intended to have the Empire and New Republic fight their final battle over Jakku's skies. His loyalists would be given directions to escape to the Unknown Regions, and everyone else would be destroyed when Jakku detonated. Fortunately, as detailed in Aftermath: Empire's End, Rebel agents were able to prevent the planet exploding. Luke Skywalker himself was at that battle, and according to Ken Liu's The Legends of Luke Skywalker he even managed to break into the Observatory. Presumably this was how Luke began to suspect something else was going on, and he began his search for the Sith Wayfinder that could have taken him to Exegol.

Presumably the Emperor was aware Luke Skywalker was dangerously close to discovering him, and so he accelerated his plans. It's surely no coincidence Lando Calrissian's daughter went missing just when he was hunting the Wayfinder, and shortly after Palpatine incited a fateful battle between Luke and his apprentice Ben Solo. With Luke unconscious, the Emperor then destroyed the Jedi Temple, an act that was blamed on Ben. The grandson of Darth Vader became Kylo Ren under Palpatine's influence, and Darth Sidious was no doubt delighted when Luke Skywalker disappeared. He remained aware the last of the Jedi could prove a potent threat, however, explaining why the First Order remained laser-focused on finding Luke in Star Wars: The Force Awakens.

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