By this logic the Emperor shouldn't have made the Primarchs at all.
All societies ultimately have to play the game of politics, which is depressingly consistent across political systems. And in this particular case, you're thinking of going after one of the greatest generals of your entire empire*, who is related to your OTHER best generals. You do NOT kill him, least of all in so public a setting. (There's also the issue that the primarchs are essentially immortal demigods and killing one of them hurts the authority of the remaining loyal sons)
*Yeah I said earlier Lorgar was bad at conquering but 1) I meant he's bad *for a primarch* which is still pretty good, and 2) that changed after Monarchia.
1) Russ tried to chastise Angron for the Butcher's Nails but unfortunately for Russ Angron had long since lost any cognitive function he once had. To the extent Lorgar had to explain to him that "no, Angron, you lost the fight against him". It's stated many times that the Butcher's nails are killing Angron, with only luck and his psykers delaying his death, to the extent that even mortal officers note he's degenerating into a maddened beast. Lorgar is only able to save his life through a demonic ascension.
2) Entire systems surrendered at the mere *suggestion* that the Night Lords might be coming. They also tended to record their torture sessions and continue broadcasting them even after they'd left iirc.
But the point I'm getting at is that the Night Lords conquered systems with extremely few casualties, relative to their peers. If you only care about humanity as a collective (which seems to be one of the Emperor's few consistent character traits) then this seems a good deal. You lose maybe a dozen astartes, a couple thousand humans, and you gain entire systems at a time.
I agree. By the logic of the tyrant, the Emperor shouldn't have made the Primarchs at all.
He created a host of supersoldiers who were genetically conditioned for loyalty to their gene-fathers. He then gave the Primarchs control of their Legions and set them loose to conquer worlds without any real supervision. This is a fantastic way to produces armies whose first loyalty is to their generals, not the ideals of the Imperial Truth or the Emperor.
Why are your generals encouraged to think of each other as brothers? Why don't you have spies and political officers watching their every word? Why are they permitted to take initiative and build close bonds with their subordinates? Why did you give power to superhuman generals, rather than expendable mortals who can be shot and replaced at a moment's notice?
Stalin-as-Emperor would
never make Primarchs. He wouldn't even make Space Marines.
The Emperor shouldn't have made the Primarchs. But if he was going to make the Primarchs, then he needed to keep them happy. He would have to manage them like Horus, who is Everybody's Friend. Or almost everybody, since Corax exists. Still, if the Emperor was as close with his Primarchs as Horus is, he wouldn't have as much reason reason to fear rebellion.
If you want to run a proper despotism, then you have to run a proper despotism. If you want to run a loose warlord confederation based on personal relationships, then you have to develop those personal relationships. The Emperor has chosen neither to cut the tall poppies nor to befriend them. This is the worst of both worlds.
Leaving aside any questions of morality, the practical problem with the Night Lords is not that they're an army of monsters who love nothing more than inflicting terror and agony. It's that they have absolutely no reason to be loyal to the Imperium.
As the Great Crusade draws to a close, the Emperor has used the Astartes to solve the "problems" created by independent human worlds and living aliens. He has replaced them with a larger problem, the existence of twenty Legions whose loyalty is to their warlords and not the Emperor.
Five minutes' study of Roman history can tell you how this story ends. And the Romans are hardly unique. Armies have been raising generals upon their shields for as long as there have been armies and generals. There are plenty of imperfect solutions to this problem, but as far as I can tell the Emperor has adopted precisely none of them.
You are seriously underestimating the amount of attention even tyrants have to pay to their militaries and their military leaders. Off the top of my head, look at the 1999 Niger coup d'etat for an example of a dictator getting shot by his own Presidential Guard (probably, anyway, things are a bit unclear)—dictators are generally extremely aware that their power comes from the barrel of a gun and that they need to keep their guns on-side.
Like, let's say Big E purges... let's say Magnus, Angron, Lorgar and Fulgrim here — aside from Angron's Chainbreakers, these are all fairly weak Legions by the numbers.
Do you think a single one of those Legions are going to quietly sit down and accept the extrajudicial execution of their Primarchs? Hell, do you think all of the other Primarchs are going to do that? They might be mostly weak Legions, but that's still four rogue Space Marine Legions. Five, if you consider that the Night Lords have been a rogue state for a while. That's hundreds and hundreds if not thousands of systems, billions if not trillions of personnel, all now fighting you, specifically. Hell, that's half the forces of the Horus Heresy, even without considering the Primarchs like Corax or Jaghatai Khan that might join forces with them on principle; or opportunists like Guilliman who might suddenly find the Emperor's rule to chafe a great deal, or hell even Rogal Dorn, who values the law extremely highly.
It wouldn't be a purge, but rather a true civil war, which is something no sane tyrant wants.
I don't understand what you're saying. Tyrants purge their generals because their generals are important and dangerous, not because they're insignificant.
A tyrant who cannot replace a defiant general is usually not a tyrant who is long for this world. Rulers have been fearful of insolent and overmighty vassals since we left the hunter-gatherer period, and for good reason.
Most of the time, your rebellious general will make a great show of loyalty until he buries the knife in your back. Lorgar has been kind enough to warn the Emperor of his disloyalty, which means that the Emperor has the advantage of doing something about it. The worst thing you can do is wait around for your general to gather his forces and move against you on his terms.
Fulgrim is a True Believer, so no need to purge him. Magnus can be placed under courteous house arrest. Angron and Lorgar need to die.
You can fight your disloyal Primarchs now, or you can fight them later, when they've had more time to gather allies. When they can fight on their terms, with the advantage of surprise. You stand in the center of your power, and the Primarchs do not have their Legions here. Kill them for their defiance, and show the rest of your generals the price of disloyalty.
A civil war is inevitable at this point, so it's best to fight on your terms. Fortunately, the Emperor is bad at this.
Edit:
In regards to the Emperor just punchsploding Lorgar into giblets right there in the council, per The First Heretic the Emperor was at one point considering purging the Seventeenth Primarch and his Legion.
And he (per Magnus the Red) quietly discussed the matter with the other Primarchs, sought their opinion on the matter. Demonstrating to them all that he VALUED their opinion and that he would not just up and arbitrarily execute someone of their station, even a Primarch who is held in contempt by most of his peers and is doing an absolute shambles of a job is still a Primarch of the Imperium and has privileges that others don't get.
Also it's worth considering just how far Canon Magnus had to go to get the boot applied to him.
He didn't just violate the Edict of Nikea (like the World Eaters, Night Lords, Alpha Legion and White Scars) he violated in the most flagrant manner possible that could not be ignored or swept under the rug, thousands of not millions dead on Terra itself and a gate to Hell ripped open under the Emperor's palace.
And Russ' original orders were still to bring him in alive, it didn't become a kill mission until Fallen Horus got involved.
Yes, but this isn't canon.
In this story, the Emperor is very clearly a tyrant and a monster. An effective tyrant does not tolerate defiance in the heart of his power, especially from an unreliable subordinate who seems determined to waste his second chance. An effective tyrant would have listened to Angron during their first meeting, when Angron named him High Rider and promised to kill him, and he would have responded by killing Angron
immediately.
If you read about tyrants getting overthrown in a coup, they're usually backstabbed by a Trusted Lieutenant who said all the right things until they put a knife in their master's back. This is because people who openly defy a tyrant usually don't live long enough to overthrow anyone.
