Spoilers for Rogue One, Darth Vader, Tarkin, Catalyst
So now that Rogue One has been released, this has been the movie that we have learned about the Galactic Empire. Of course ever since Disney has bought Lucasfilm and established a new canon, this should not be unexpected. In most of the media focusing on the time of the reign of the Empire, they have gone to great lengths to show the nuances of the Empire. Throughout the new canon, we see that the Empire is full of backstabbing and power plays and in fact is encouraged by Emperor Palpatine himself…implied to be a way of keeping people from usurping him.
Catalyst which is a direct prequel to Rogue One focuses on the relationship between Tarkin and Krennic. Krennic wants to be where Tarkin is in the ranks of the Empire. Tarkin is fully aware of this and the two arguably spend more time feuding with one another than their enemies in the book. In fact, Krennic starts a small war just to occupy Tarkin’s time. By the end of the novel, we see Krennic where he is at the beginning of Rogue One. A man desperate to reclaim what he believes is his (Galen Erso) all so that he can reclaim his glory and rise up in the ranks.
In Darth Vader, we learn that not even the Emperor’s best instrument of destruction is immune to this. That Palpatine has been grooming potential successors to Vader since Vader was born. This probably shouldn’t have been unexpected considering what we know of Palpatine but it’s how Vader reacts. Seeing this as a test to reclaim favor with the Emperor after the failure of the Death Star.
So the Empire was doomed to fail from the start. The Sith have longed held the Rule of Two which is something that breeds deceitfulness and mistrust. So how can a government controlled by the leader of the Sith be any different. We see in the materials set after Return of the Jedi that the Empire collapses almost immediately because they’ve never really been forced to work together without their figureheads.