Quote Originally Posted by deuterio12 View Post
Wrong, he still had some shreds of sanity and decency. It's when the emperor arrives and separates him from his companions and then makes him watch as they're butchered that he completely loses it.
Hardly the fault of the Adeptus Terra either way - and a pretty poor reason for deciding to join in with the extermination/enslavement of the human race.

He broke it because the Emperor needed to be warned. The emperor then thanked him by unleashing Russ on Magnus, thus forcing him to completely turn to chaos or turn in furry food.
Except, as Outcast Dead lays out, the Emperor already knew. A Thousand Sons also portrays Magnus' idea as wanting to prove that sorcery can be useful (and his being a puppet for Tzeentch the whole time after their deal).
Magnus also ignored Russ' pleas to surrender, and willingly accepted his punishment (in fact exacerbating the punishment by ignoring Russ, who was willing to simply bring him in to Terra unharmed [Prospero Burns]) as he believed he deserved it for breaking his father's wishes. He only took the out offered by Tzeentch when he couldn't bear seeing his sons slaughtered anymore.

Not really. Lorgar started worshiping the emperor. The emperor rejected that kind of behaviour and claimed there was no such thing as gods (aka a blatant lie). Lorgar then goes to find out that there are indeed gods, and they want to be worshiped, and thus the IoM is being built in lies.
Thus he decides to destroy humanity. If Kor Phaeron and Erebus hadn't been going around worshipping the chaos gods Lorgar wouldn't have had them whispering in his ear (or if Lorgar told them to bugger off, or questioned the Emperor on this new information). Lorgar sided with the gods, not because he had some pathalogical desire to give worship, but because the gods told him they sought to meld humans with warp powers into single perfect beings. He saw this as the end result of worship, achieving a higher plain of existence.
This is, of course, completely wrong (i.e. an outright lie) as a very select few acheive daemon prince status, and most are consumed or destroyed.

Note that at no point does he question "hey, maybe there's a reason dad never told me about this?", or go and ask the Emperor why he lied.

The road to hell the warp is filled with good intentions. Joining the side with daemon weapons and daemons however wasn't exactly a very smart choice if you want to fight against chaos.
The plan was that if Horus won he'd end up exterminating humanity and starve the chaos gods of mankind's power, killing them permanently.

Yet the Emperor picked him anyway as the warmaster.:smallamused

:Lo and behold, the first Commander Incopentus in the IoM's history! The emperor is guilty of seting this dangerous standard for the IoM of not bothering to check if the people you're puting in charge are idiots and/or easily trickeable.
The issue is that up until that point Horus has been shown to be super intelligent, cunning and wise - his fall really makes no sense in character as presented by the novels.
It's adaption decay from the 20 odd years of the story. In the first version of the Heresy tale Horus was simply a man, the greatest general of humanity, who was straight up posessed by a warp entity.
If HH series Horus was posessed his turn to evil, while boring, would make sense. As is he gets one wobbly vision after getting stabbed and decides to believe it over every other piece of evidence he has.

I'd call that the writers having to force the plot to fit the background rather than any sinister foreshadowing of the future of the Imperium or incompetence on the Emperor's part. We are, after all, told explicitly that Horus is the greatest commander in the Galaxy - master of war, philosppher of tactics, leader of men.
It is presented as an undeniable fact backed up by his litany of successes. Horus was put in charge because he was quite literally made to be the perfect commander. His fall, as written, is the weakest of any of the Primarchs and shows that it was quite early in the series when they'd not finalised a lot of the tone and feel of the series. Compare the suddenness of Horus' heel turn to Magnus', which only comes at the very end of A Thosand Sons and isn't really a turn at all, or to Lorgar's which is very nuanced and spread across several books.

Fully IoM fault. Curze was actualy doing a fine job of turning that world in a better place, then when he leaves whatever administration forces that were left behind let it get to the old ways.
If by 'fine job' you mean murdering everyone he feels is wrong, and terrorising the population into submission (pre-Emperor). Weren't you complaining about the Imperium doing that sort of thing in the 41st millenium?
He didn't institute any real societal or political changes, he just terrorised everyone until they behaved and then left - I'm hardly surprised the planet went back to the crapper.
Also note that his solution was not to re-pacify the planet, but to blow it up. I guess that's the Imperium's fault for giving him weapons that powerful, right?

Yet the emperor was completely random on how to deal with those issues:

-Angron performing lobotomies on his troops turning them into bloodthirsty monsters? Let it slide for emperor knows how much time.

-Magnus tries to warn him of his brother's treacheries with magic? Unleash the furry hordes on him!
It's not a lobotomy, and some of the background material says the Emperor was going to censure the World Eaters (and Night Lords) for their ever mroe extreme actions, but they rebelled first.
Magnus I've already covered.

Please remind me, how exactly is they not knowing what they're doing, and yet doing it anyway, a better thing?
I'm not saying it is - I'm saying it's worse and the perpetrators are culpable as they didn't think "hmm... maybe I should ask the Emperor, who obviously knows more about this stuff than he's saying, what he thinks of these visions/premenitions/ideas rather than just doing it anyway?"

And now we've hit the critical point. The history only works if the emperor seriously believes "If I close everybody eyes and ears, chaos can't hurt us!".
And it could've - Alpharius' plan was the same thing except everybody dies instead of everybody just forgetting about Chaos. Religions can be wiped out, as can history, by supressing it thorougly enough - it's one of the main themes of the Heresy books even!

And the emperor is the central point of the IoM. Which brings us to

For all effects, the IoM is the emperor. His orders were and are still absolute (if you claim you hear his voice, then you're given high positions instead of being thrown in the loony house). Thus all of the emperor's faults end up reflecting in the IoM. His errors back then echo trough 10.000 years.
You're arging about the culpability of the Imperium for the fall of the Primarchs using both the pre-and post Heresy governmental systems? I know time flows differently in the warp but come on, that's a real stretch.

The Primarchs were not bound by the Adeptus Terra, which hadn't fully formed by the time the Heresy broke out, and were operating as military commanders. They conquered worlds and carried the banner of Terra to the stars, the administration of the worlds after they left completely independant of them (one of the things Lorgar got wrong).
The Emperor ordered them to do and not do certain things. One common thing the traitors almost all have is that they did not do or did anyway these things.
The faults of the 'modern' Imperium are mostly things the Emperor was against - his worship, superstition, dogma. In Outcast Dead an Astropath has visions of the 40k universe, and is so horrified by what he sees compared to waht they're working towards, he kills himself.

So if the traitors hadn't turned, the Imperium would still be lead by the Emperor, had access to the webway, a complete STC system, have little need for Inquisitors, and be generally a pretty cool place to be.

And they're actualy right for it. Many of them were put in positions where chaos was indeed the only answer (Lorgar wanted something to worship, Magnus had no other way to try to warn the emperor, Angrom wanted revenge, etc).
In the case of Lorgar, lacking something is no reason to taking the absolute worst possible alternative. Wish you had a girlfriend? Have some heroin! Your boss told you off and made you do a job you don't like? Kill him and all your co-workers!
When those things happen in real life it is a tradgedy, and the person involved is either seen as a victim of those who manipulated them or an insane monster.

Magnus didn't need to warn the Emperor, he already knew. Furthermore Magnus acknowledged that he did was a terrible, unforgivable mistake and the Emperor was right all along.

Angron was angry his fellows were left to die - of course he's right to decide to worship the god of bloodshed and seek to murder ever living thing in the galaxy!

There of course existed Option C, (A being do as they're told, B being turn to evil) which none of them explored - talk to the Emperor about these things. But, I suppose that's the Imperium's fault too