Why did the Empire need Force-wielding inquisitors and agents?

Question

The Galactic Empire upheld the Sith tradition of the Rule of Two meaning that there could ever be one Sith master and one Sith apprentice.

However, at the same time, the Empire made use of other dark side Force users to track down Jedi, rebels, etc. Some examples are Jerec, Malorum, prophets of the dark side, etc. (also the inquisitor in the Rebels TV series).

Why did the Empire need to use inquisitors and train them in the ways of the dark side when technically, they could pose as a threat to the Rule of Two and overthrow the current master and apprentice? Couldn't Vader and Sidious track down remaining Jedi on their own?

Answer 1

The short answer is that the Rule of Two is not absolute¹: the Sith can (and often do) utilize non-Sith Dark Jedi (like inquisitors) to accomplish their goals. With an entire galaxy to rule, it's understandable that the Sith would use Dark Jedi to help root out Jedi and rebels.

It is perhaps better to view the Rule of Two as a system in which only one Sith is the Master of the Order, and his apprentice is the heir (and there can only be one heir). But that's not to say the Sith cannot have dark side allies; all Sith are dark side users but not all dark side users are considered Sith.

Moreover, the Rule of Two was created by Bane in part to prevent the Sith Order from weakening itself from within and thus making itself unable to fight a strong Jedi Order. From the Rule of Two novel:

The Sith had existed in one form or another for thousands of years. Throughout their existence they had waged an endless war against the Jedi … and one another. Time and time again the followers of the dark side had been thwarted by their own rivalries and internal power struggles. A common theme resonated across the long history of the Sith Order. Any great leader would inevitably be overthrown by an alliance of his or her followers. Lacking a strong leader the lesser Sith would quickly turn against one another, further weakening the Order.

But with the Jedi Order mostly destroyed by the time of the Galactic Empire, it was less important to maintain the Rule of Two. The Sith still had to guard against internal conflict, but they no longer faced such a significant threat from the Jedi.

Also, Palpatine could not hunt down rebels directly. Part of Palpatine's hold on power depended on his public image as an old man viciously attacked and deformed by the Jedi attempting to seize power. It was not well known that Palpatine was a Sith Lord. The canon novel Tarkin indicates that not even Grand Moff Tarkin knew that Palpatine (and Vader) were Sith -- he only suspected it:

There were many stories about what had occurred that day in the chancellor’s office. The official explanation was that members of the Jedi Order had turned up to arrest Supreme Chancellor Palpatine, and a ferocious duel had ensued. The matter of precisely how the Jedi had been killed or the Emperor’s face deformed had never been settled to everyone’s satisfaction, and so Tarkin had his private thoughts about the Emperor, as well. That he and Vader were kindred spirits suggested that both of them might be Sith.

Palpatine's true genius lay in his political prowess anyway -- he was more effective as a political ruler than a combatant. He did kill a few Jedi in personal combat during the Clone Wars, but he politically engineered the destruction of the entire Jedi Order.

Overall, there were many reasons for the Sith to use Dark Jedi to help them. On the other hand, the risks were fairly small: Palpatine was very powerful -- even Vader was too afraid to confront the Emperor by himself. Palpatine's downfall was ultimately due to his miscalculation of Vader's love for his son, not because he took on dark side allies.

¹Palpatine's master, Darth Plagueis, did not obey the Rule of Two absolutely in that he allowed Palpatine to take on Darth Maul as his apprentice. Palpatine himself obviously did not obey it absolutely, either, and Vader took on a secret apprentice. It's not the Rule of Exactly Two.

Answer 2

In addition to Null's excellent answer:

1. With extremely rare exceptions, random individual "Force-wielding inquisitors and agents" are not really a threat to a trained, powerful Sith Master (who, if you recall, could dispatch Jedi Masters with ease and Master Yoda with a decidedly lopsided fight)

   He also happens to be a Galactic Emperor with appropriate level of protection (Royal Imperial guards) and intelligence services (which can detect and prevent conspiracies among inquisitors and agents).

2. I'm not even sure that most of those Force-wielding inquisitors and agents were aware that the Emperor was a Sith Master who needed to be attacked - many of them (think Mara Jade) were not the "mad rush to power" type people - they were merely Force-equipped servants, by training and mentality.

Answer 3

These answers cover lot of great ground, but I would also add that additional Dark Jedi serve as an insurance policy for the Emperor against Vader's failure or betrayal.

In the canon Marvel Darth Vader comic series, Vader learns of a program of lightsaber-wielding cyborgs that the Emperor has been developing is secret, and has to fight them to prove his skill and worth after losing the first Death Star. In Darth Vader #6, it's clear that the Emperor has been auditioning replacement apprentices ever since he successfully turned Anakin, which makes sense because if Vader were to die in combat or need to be killed for sedition, it would be disastrous for the Emperor to have to start at zero when training a new apprentice.

Answer 4

Although the Rule of Two is in place, I believe that the Sith needed assistants in tracking down their enemies whenever they were too preoccupied with snippy politicians or rebellious civilians (which, of course, is what the Inquisitors of Rebels are tasked with doing). Inquisitors do pose as a threat to the current Sith master and apprentice, but if they receive a decent amount of training--not too much as to overthrow the two, yet not too little to prove incompetent--then they would function well in hunting down the Jedi.

Also, there were almost ten thousand Jedi in the Order before Vader and Sidious had them exterminated (as quoted by Kanan Jarrus, a Jedi protagonist in Rebels). Judging from that figure, at least a hundred may have lived through Order 66. Even if the number was greater, the Sith would still need Inquisitors to hunt down and kill the less powerful Jedi, while they could deal with surviving Jedi masters themselves.

Answer 5

Darth Sidious i.e. Emperor Palpatine, used Force users before he took over the Galactic Empire. His 'aid' Sly Moore, seen in Attack of the Clones and Revenge of the Sith was a Force user. Have a Force user like Sly can easily be understand for the advantages of helping Palpatine manoeuvre and influence, also expose issues within his Empire. This reason is overall the same for all Force users within the Galactic Empire under Darth Sidious' and Darth Vader's leadership.

Sly Moore:

A pale Umbaran, Sly Moore served as Palpatine’s senior administrative aide during his chancellorship, attending to countless affairs of state. Moore’s enigmatic silence made her the object of considerable curiosity on Coruscant, with rumors abounding about her past and mysterious abilities she supposedly possessed. She was one of the few people who knew of Palpatine's true identity as Darth Sidious.

Have Force users within the military helping to direct battles was also an effective tool. Having Force users within the Imperial Courts, who would also be more cultured among the Ancient Houses would all work for the same reason.

The ministers accompanying Palpatine in Return of the Jedi, were also Force users. Sim Aloo, Janus Greejatus, Kren Blista-Vanee, Ars Dangor. The Imperial Ruling Council that managed the daily affairs of the Empire, and its members wielded considerable powers. They had direct access to the Emperor, and all Moffs, generals and admirals reported to them. Palpatine was preparing the Moffs with these ministers of the IRC.

Mara Jade was a Hand that dealt more directly in the Imperial military and courts whereas Roganda Ismaren dealt more directly in the Royal Court and Ancient Houses. One of Palpatines 12 Grand Admirals with also Force strong. Along with 2 Imperial Engineers Bevel Lemelisk and Birra Seah.

Palpatine was not interested in hunting down surviving Jedi, as information came up he would send Hands or Inquisitors to investigate. But he was more concerned with the rule of his Empire and extending that. Which also meant dealing with external threats beyond 'rebellions and Jedi'.

The characters in the films most likely were always force sensitive, the novels did not take them where George Lucas did not want them to go. The ministers that surrounded Palpatine in ROTJ even had the same skin and eye tones resulting from use of the Dark side.