Despite his exceptional skills in lightsaber combat and his mastery of the dark side, Palpatine was no less susceptible to fear, one of the primary emotions of the dark side, than any other Sith. Contrary to Darth Bane's strict belief that the Apprentice must prove his worthiness by striking down the Master in open combat, Palpatine chose to murder his Master, Darth Plagueis in his sleep, rather than confront him directly. In an effort to gain Anakin Skywalker's sympathy, Palpatine appeared to cower before Windu, which may have been out of both practicality and desperation due to such a calculated risk. Nevertheless, he only attacked Mace Windu after the Jedi Master had been disarmed and rendered helpless by Skywalker.
After his ascension as Emperor, Palpatine displayed visible fear after being attacked by a powerful Force push from Yoda. He attempted to flee rather than fight, and only confronted Yoda when he appeared to have no other choice in the matter. During the battle over Coruscant, General Grievous considered Palpatine a coward when deducing that the Chancellor was hiding under the consoles while Grievous's battle droids fought Anakin Skywalker and Obi-Wan Kenobi on the Invisible Hand. However Grievous did not know that Palpatine was actually Darth Sidious.
Since Palpatine was in no position to reveal his Sith identity until the right time, he was forced to refrain from using his Force powers to protect himself while in an extremely dangerous situation that presented considerable risk to his life. Before his death, Mace Windu sensed Palpatine's fear and believed that it was the cause of the Sith Lord's defeat.[19] Many years later, Luke Skywalker also detected the same traces of fear that resided with Palpatine, as it did inside all who adhered to the Dark side of the Force. Fear ultimately proved to be Palpatine's achilles' heel as it caused him to constantly plot and devise schemes against his enemies, which ultimately lead to the unexpected creation of the Rebel Alliance and the eventual downfall of his empire.
