Star Wars has hinted that the Rebel Alliance may not have been entirely heroic after all - it's possible they were just a trick to undermine the Empire. Although Palpatine was a master strategist, the truth is that his Empire was always going to be resisted. On the eve of his ascension to Emperor, 2000 senators registered a petition of protest. Several of those senators - including the likes of Bail Organa and Mon Mothma - went on to become major players in the Rebel Alliance.
And yet, it's always seemed strange that it took the Rebels so long to actually organize themselves against the Empire. Palpatine's Empire ruled the galaxy for nearly two decades, and was remarkably successful at crushing dissent. While cells of rebels began to spring up across the galaxy, they were uncoordinated, and spent as much time bickering among themselves as taking on the Empire. That was displayed quite prominently in Rogue One, which featured a sub-plot about the division between Mon Mothma and Saw Gerrera. The Rebels only began to come together a couple of years before Star Wars: A New Hope - but what changed to lead them to become more well-organized?
The latest Star Wars novel, Timothy Zahn's Thrawn: Treason, is set just two years before A New Hope - and it offers a disturbing possibility. Grand Admiral Thrawn learns that the galaxy is faced with a new threat, the Grysk, a race of slavers from the Unknown Regions who desire to conquer the Empire. His Imperial allies openly speculate that the growing rebellion could be fueled in part by the Grysk.
The Grysk excel at manipulating a person into becoming a willing slave, using their every fear and doubt against them. When the process is complete, a Grysk subject is even content to die on their masters' behalf. Making matters worse, the Grysk enjoy using subterfuge to achieve their goals. Grand Admiral Thrawn and Darth Vader brought down two separate covert invasions, but it's reasonable to assume the aliens had some other strategies in play.
It's not hard to imagine a scenario where the Grysk recognized that they could not bring the Empire down directly. After all, they'd already been defeated twice. Their best strategy, then, would be to weaken the Empire from within; to fan the flames of rebellion, to encourage the various rebel cells to work together, and ultimately trigger a galactic civil war. By this reading, the Grysk may have captured key Rebel operatives and turned them into their slaves, deploying them to help create the Rebel Alliance. Presumably they then retreated from active involvement in the Rebellion, given a Jedi like Luke Skywalker would have eventually sensed that something was wrong.
Of course, it's possible this theory was just Imperial paranoia. At the same time, though, it certainly seems rather too convenient that the fragmented rebel cells came together right at the moment the Grysk were plotting to bring down the Empire. The one question, then, is why there's currently no evidence the Grysks struck again when the Galactic Civil War was at its height. Presumably that will be explored in future tie-ins.
