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 Dakka Wolf wrote:

 djones520 wrote:

 Grimgold wrote:
The lion was the "warmaster" Equivalent for the imperium secundus, and both Guilliman and Sanguinius choose him for that role because they both knew he was the best fit. The problem with the lion is, he is too prideful. The smallest slight can set him off, and make him take stupid actions. His battle with Leman Russ, dumb, trying to kill Konrad Cruze in front of Guilliman and Sanguinius, dumb, banishing luther, dumb, killing Nemiel, also dumb. The common thread to all of those dumb actions is a slight to his pride.

One wonders how he would handle an actual defeat, but we may never find out because he hasn't been beaten when leading an army. The closest we've seen to him losing is him not wiping out the entire force that's facing him, or sparing the man who raised him like a father.

You realize Russ was totally responsible for that fight, right? In Russ's own words. Jonson precipitated it because he was trying to save the lives of his own Legionaries, because Russ left the battlefield, causing the fight to drag out. When Russ returned, he attacked the Lion because he felt Jonson broke his word.

There is an entire novel, "told" by Leman Russ, that covers that event now.

'tis true.
However.
In that same book Russ was the first one to see the stupidity of his actions, the Lion never saw his own idiocy at all and even took a sword to Russ years and a whole Heresy later to "release the bad blood between them" and even perceptive of that Russ just took it.

Yeah, in all fairness though the lion was the adult in the room, he should have stopped the fight with Russ, instead as soon as the first blow was struck he lost his cool. When russ backed off and laughed, that should have been the end of it, but no the lion had have the last blow.

 Grimgold wrote:

 Dakka Wolf wrote:

 djones520 wrote:

 Grimgold wrote:
The lion was the "warmaster" Equivalent for the imperium secundus, and both Guilliman and Sanguinius choose him for that role because they both knew he was the best fit. The problem with the lion is, he is too prideful. The smallest slight can set him off, and make him take stupid actions. His battle with Leman Russ, dumb, trying to kill Konrad Cruze in front of Guilliman and Sanguinius, dumb, banishing luther, dumb, killing Nemiel, also dumb. The common thread to all of those dumb actions is a slight to his pride.

One wonders how he would handle an actual defeat, but we may never find out because he hasn't been beaten when leading an army. The closest we've seen to him losing is him not wiping out the entire force that's facing him, or sparing the man who raised him like a father.

You realize Russ was totally responsible for that fight, right? In Russ's own words. Jonson precipitated it because he was trying to save the lives of his own Legionaries, because Russ left the battlefield, causing the fight to drag out. When Russ returned, he attacked the Lion because he felt Jonson broke his word.

There is an entire novel, "told" by Leman Russ, that covers that event now.

'tis true.
However.
In that same book Russ was the first one to see the stupidity of his actions, the Lion never saw his own idiocy at all and even took a sword to Russ years and a whole Heresy later to "release the bad blood between them" and even perceptive of that Russ just took it.

Yeah, in all fairness though the lion was the adult in the room, he should have stopped the fight with Russ, instead as soon as the first blow was struck he lost his cool. When russ backed off and laughed, that should have been the end of it, but no the lion had have the last blow.

the novel that depicts the whole thing makes it even worse. as apparently in the aftermath of the bloody seige of terra, The Lion was still pissy about it and demanded the fight be finished. Russ apparently wasn't intreasted (it seemed so ya know PETTY in the aftermath of the Heresy) but apparently the Lion needed to give Russ a good stabbing to be sastified.

 Grimgold wrote:

Yeah, in all fairness though the lion was the adult in the room, he should have stopped the fight with Russ, instead as soon as the first blow was struck he lost his cool. When russ backed off and laughed, that should have been the end of it, but no the lion had have the last blow.

I just had to quote this out of amusement.

When it comes to his brothers Johnson has been the adult in the room a grand total of once.
Ironically Russ was being the adult in the room at the same time which means Russ has been the adult in the room twice.

When Horus was named Warmaster the Wolf and the Lion were two of the five top options and along with Girlyman and Sangy the most mature acceptance of missing out. Russ never believed himself the greatest brother and didn't care for extra responsibility. The Lion had a good long brood about it but did find the time to track down Horus and shake his hand.

BrianDavion wrote:

the novel that depicts the whole thing makes it even worse. as apparently in the aftermath of the bloody seige of terra, The Lion was still pissy about it and demanded the fight be finished. Russ apparently wasn't intreasted (it seemed so ya know PETTY in the aftermath of the Heresy) but apparently the Lion needed to give Russ a good stabbing to be sastified.

Is the Lion still angry about Dulan or angry that if Russ hadn't had stopped to assist Imperial Worlds on their way back to Terra they might have been able to help the Emperor? In WD 233 it gives a pretty good account of the relationship between Russ and the Lion. Some of it has been changed now and not written yet but the Angels and the Wolves arrive on Terra and do some mopping up but the don't realise that the Emperor has been wounded. After the Emperor is interred on the Golden Throne The Lion has a go at Russ and challenges him. Russ, too distraught, simply bares his chest and the Lion stabs him, pulling the blade at the last minute realising his folly. Then they become best buds.

 Pilau Rice wrote:

BrianDavion wrote:

the novel that depicts the whole thing makes it even worse. as apparently in the aftermath of the bloody seige of terra, The Lion was still pissy about it and demanded the fight be finished. Russ apparently wasn't intreasted (it seemed so ya know PETTY in the aftermath of the Heresy) but apparently the Lion needed to give Russ a good stabbing to be sastified.

Is the Lion still angry about Dulan or angry that if Russ hadn't had stopped to assist Imperial Worlds on their way back to Terra they might have been able to help the Emperor? In WD 233 it gives a pretty good account of the relationship between Russ and the Lion. Some of it has been changed now and not written yet but the Angels and the Wolves arrive on Terra and do some mopping up but the don't realise that the Emperor has been wounded. After the Emperor is interred on the Golden Throne The Lion has a go at Russ and challenges him. Russ, too distraught, simply bares his chest and the Lion stabs him, pulling the blade at the last minute realising his folly. Then they become best buds.

the whole events of the duel laid heavily over them. in the novel after seeing the emperor Interred Russ flees the scene, deep into the Imperial palace before passing out (he apparent;y hadn't slept the entiore way to Terra) when he wakes up (after having a vision where he chats with the emperor) he finds the Lion standing over him it turns out that they're underneath a mural dedicated to the compliance of the world they fought their duel on. that brings it back, I mean it's clear there is more there, but the Lion also wants to "finish the duel that had begun so long ago" although from something the Lion says I almost wonder if he had been hoping Russ would kill him so he didn't have to ebar the guilt.

The lion, thats been stated a bunch of times because its kinda his shtick

Overall it's definitely Guilliman. That said Perturabo is better in siege assault, Dorn better in defense, etc. That said, all the primarchs were likely brilliant generals, but Guilliman, Dorn, Perturabo, Alpharius, and Horus stand well above the others in my opinion. Top three are probably Guilliman > Horus > Perturabo.

 ripjaw wrote:
Overall it's definitely Guilliman. That said Perturabo is better in siege assault, Dorn better in defense, etc. That said, all the primarchs were likely brilliant generals, but Guilliman, Dorn, Perturabo, Alpharius, and Horus stand well above the others in my opinion. Top three are probably Guilliman > Horus > Perturabo.

See I would disagree, girlyman was the best diplomat and leader aside from Horus. But for battlefield twchtition, that goes to lion seeing as he has always been regarded and portrayed and the best tactition.

BrianDavion wrote:

 Grimgold wrote:

 Dakka Wolf wrote:

 djones520 wrote:

 Grimgold wrote:
The lion was the "warmaster" Equivalent for the imperium secundus, and both Guilliman and Sanguinius choose him for that role because they both knew he was the best fit. The problem with the lion is, he is too prideful. The smallest slight can set him off, and make him take stupid actions. His battle with Leman Russ, dumb, trying to kill Konrad Cruze in front of Guilliman and Sanguinius, dumb, banishing luther, dumb, killing Nemiel, also dumb. The common thread to all of those dumb actions is a slight to his pride.

One wonders how he would handle an actual defeat, but we may never find out because he hasn't been beaten when leading an army. The closest we've seen to him losing is him not wiping out the entire force that's facing him, or sparing the man who raised him like a father.

You realize Russ was totally responsible for that fight, right? In Russ's own words. Jonson precipitated it because he was trying to save the lives of his own Legionaries, because Russ left the battlefield, causing the fight to drag out. When Russ returned, he attacked the Lion because he felt Jonson broke his word.

There is an entire novel, "told" by Leman Russ, that covers that event now.

'tis true.
However.
In that same book Russ was the first one to see the stupidity of his actions, the Lion never saw his own idiocy at all and even took a sword to Russ years and a whole Heresy later to "release the bad blood between them" and even perceptive of that Russ just took it.

Yeah, in all fairness though the lion was the adult in the room, he should have stopped the fight with Russ, instead as soon as the first blow was struck he lost his cool. When russ backed off and laughed, that should have been the end of it, but no the lion had have the last blow.

the novel that depicts the whole thing makes it even worse. as apparently in the aftermath of the bloody seige of terra, The Lion was still pissy about it and demanded the fight be finished. Russ apparently wasn't intreasted (it seemed so ya know PETTY in the aftermath of the Heresy) but apparently the Lion needed to give Russ a good stabbing to be sastified.

"He knew he wouldn't kill me,' Russ said, grimly amused. 'He told me that afterwards. He turned the blade aside, right at the last moment. It still took a week to heal. That damned sword.'

He chuckled Mornfully. 'It needed to be done, though. It cured the bad blood between us. Drained it out. We could speak again, after that.'

...

'He could keep a secret. He saw our imperfection, and he suffered it to remain, and that was the heart of his nobility. In the end, then, he truly was better then us. The archetype of Legions, the First of all..."

Leman Russ' opinion seems to differ from yours.

Leman Russ' opinion seems to differ from yours.

not really, as I said the Lion apparently needed to give Russ a good stabbing.


BTW you'll notice his comment on "that damned sword" there seems to be some evidance stacking up that there is something special about the Lion Sword

 Backspacehacker wrote:

 ripjaw wrote:
Overall it's definitely Guilliman. That said Perturabo is better in siege assault, Dorn better in defense, etc. That said, all the primarchs were likely brilliant generals, but Guilliman, Dorn, Perturabo, Alpharius, and Horus stand well above the others in my opinion. Top three are probably Guilliman > Horus > Perturabo.

See I would disagree, girlyman was the best diplomat and leader aside from Horus. But for battlefield twchtition, that goes to lion seeing as he has always been regarded and portrayed and the best tactition.

Guilliman was described as the best logistician and organiser of the lot, not diplomat or leader. He was not good at diplomacy; even before the Heresy he'd alienated Alpharius, Lorgar, Angron, Perturabo, and the Lion, and then came up with the codex to piss of more Loyalist ones. He was close with Russ, Ferrus, Dorn, and as almost everyone, Vulkan, Sanguinius, and Horus.

Testimonies:

Lion El'Johnson - "Insult me again, brother, and theoretically I will punch you in your practical face"
Angron - "What would you know of struggle, Perfect Son? When have you fought against the mutilation of your mind? When have you had to do anything more than tally compliances and polish your armour?" [...] "The people of your world named you Great One. The people of mine called me Slave. Which one of us landed on a paradise of civilization to be raised by a foster father, Roboute? Which one of us was given armies to lead after training in the halls of the Macraggian high-riders? Which one of us inherited a strong, cultured kingdom? And which one of us had to rise up against a kingdom with nothing but a horde of starving slaves? Which one of us was a child enslaved on a world of monsters, with his brain cut up by carving knives? Listen to your blue-clad wretches yelling of courage and honour, courage and honour, courage and honour. Do you even know the meaning of those words? Courage is fighting the kingdom which enslaves you, no matter that their armies outnumber yours by ten-thousand to one. You know nothing of courage. Honour is resisting a tyrant when all others suckle and grow fat on the hypocrisy he feeds them. You know nothing of honour."

I can probably look up where Guilliman forces him and the Word Bearers to kneel to the Ultramarines in the ashes of Monarchia too, and just look up the Tesstra Compliance for Alpharius.

The Emperor forced them to kneel. Not Guilliman.

 djones520 wrote:
The Emperor forced them to kneel. Not Guilliman.

now now don't let facts get in the way of bashing Gulliman his other arguements are similarly based on... a creative interpretation of the facts

In the unanimous judgment of the Primarchs themselves. the answer is Horus.

 Manchu wrote:
In the unanimous judgment of the Primarchs themselves. the answer is Horus.

Majority juedgement, definitely not unanimous. The Lion at least disagreed as did Horus himself (who felt it should have been Sanguinius).

 ChazSexington wrote:

Guilliman was described as the best logistician and organiser of the lot, not diplomat or leader. He was not good at diplomacy; even before the Heresy he'd alienated Alpharius, Lorgar, Angron, Perturabo, and the Lion, and then came up with the codex to piss of more Loyalist ones.

It fairness the stuff with Lorgar wasn't his fault and Angron was bitter and hated almost everyone. I don't recall Guilliman alienating Perturabo though. Breaking up the Legions was ordered by the High Lords of Terra so it's unfair to blame Guilliman for that.

As fro the Tesstra Compliance, Alpharius by his own admission deliberately dragged out a compliance so he could show off, resulting in far greater casualties among the populace they were trying to assimilate into the Imperium. Guilliman might not have been diplomatic about it but Alpharius' methods were definitely wanting.

SomeRandomEvilGuy wrote:

 ChazSexington wrote:

Guilliman was described as the best logistician and organiser of the lot, not diplomat or leader. He was not good at diplomacy; even before the Heresy he'd alienated Alpharius, Lorgar, Angron, Perturabo, and the Lion, and then came up with the codex to piss of more Loyalist ones.

It fairness the stuff with Lorgar wasn't his fault and Angron was bitter and hated almost everyone. I don't recall Guilliman alienating Perturabo though. Breaking up the Legions was ordered by the High Lords of Terra so it's unfair to blame Guilliman for that.

As fro the Tesstra Compliance, Alpharius by his own admission deliberately dragged out a compliance so he could show off, resulting in far greater casualties among the populace they were trying to assimilate into the Imperium. Guilliman might not have been diplomatic about it but Alpharius' methods were definitely wanting.

Actually breaking up the legions was a decision made by each leader it's not something that can be blamed on Guilliman at all. Russ for example chose to use the order as toilet paper.

 Dakka Wolf wrote:

SomeRandomEvilGuy wrote:

 ChazSexington wrote:

Guilliman was described as the best logistician and organiser of the lot, not diplomat or leader. He was not good at diplomacy; even before the Heresy he'd alienated Alpharius, Lorgar, Angron, Perturabo, and the Lion, and then came up with the codex to piss of more Loyalist ones.

It fairness the stuff with Lorgar wasn't his fault and Angron was bitter and hated almost everyone. I don't recall Guilliman alienating Perturabo though. Breaking up the Legions was ordered by the High Lords of Terra so it's unfair to blame Guilliman for that.

As fro the Tesstra Compliance, Alpharius by his own admission deliberately dragged out a compliance so he could show off, resulting in far greater casualties among the populace they were trying to assimilate into the Imperium. Guilliman might not have been diplomatic about it but Alpharius' methods were definitely wanting.

Actually breaking up the legions was a decision made by each leader it's not something that can be blamed on Guilliman at all. Russ for example chose to use the order as toilet paper.

actually thats wrong. Russ also spun off a sucessor chapter, forming the wolf brothers. he rejected the codex astartes, but he did split his chapter. truthfully if you look at it, almost all the surviving primarchs, except Dorn, cut a deal with Gulliman in one form or another

BrianDavion wrote:

 Dakka Wolf wrote:

SomeRandomEvilGuy wrote:

 ChazSexington wrote:

Guilliman was described as the best logistician and organiser of the lot, not diplomat or leader. He was not good at diplomacy; even before the Heresy he'd alienated Alpharius, Lorgar, Angron, Perturabo, and the Lion, and then came up with the codex to piss of more Loyalist ones.

It fairness the stuff with Lorgar wasn't his fault and Angron was bitter and hated almost everyone. I don't recall Guilliman alienating Perturabo though. Breaking up the Legions was ordered by the High Lords of Terra so it's unfair to blame Guilliman for that.

As fro the Tesstra Compliance, Alpharius by his own admission deliberately dragged out a compliance so he could show off, resulting in far greater casualties among the populace they were trying to assimilate into the Imperium. Guilliman might not have been diplomatic about it but Alpharius' methods were definitely wanting.

Actually breaking up the legions was a decision made by each leader it's not something that can be blamed on Guilliman at all. Russ for example chose to use the order as toilet paper.

actually thats wrong. Russ also spun off a sucessor chapter, forming the wolf brothers. he rejected the codex astartes, but he did split his chapter. truthfully if you look at it, almost all the surviving primarchs, except Dorn, cut a deal with Gulliman in one form or another

Russ only wanted the high numbers that successor chapters can generate, that's why he cut the Wolves in half as opposed to the ten or so successors that Guilliman made at the same time.
Russ wanted other recruitment worlds to supplement Fenris.

 Dakka Wolf wrote:

BrianDavion wrote:

 Dakka Wolf wrote:

SomeRandomEvilGuy wrote:

 ChazSexington wrote:

Guilliman was described as the best logistician and organiser of the lot, not diplomat or leader. He was not good at diplomacy; even before the Heresy he'd alienated Alpharius, Lorgar, Angron, Perturabo, and the Lion, and then came up with the codex to piss of more Loyalist ones.

It fairness the stuff with Lorgar wasn't his fault and Angron was bitter and hated almost everyone. I don't recall Guilliman alienating Perturabo though. Breaking up the Legions was ordered by the High Lords of Terra so it's unfair to blame Guilliman for that.

As fro the Tesstra Compliance, Alpharius by his own admission deliberately dragged out a compliance so he could show off, resulting in far greater casualties among the populace they were trying to assimilate into the Imperium. Guilliman might not have been diplomatic about it but Alpharius' methods were definitely wanting.

Actually breaking up the legions was a decision made by each leader it's not something that can be blamed on Guilliman at all. Russ for example chose to use the order as toilet paper.

actually thats wrong. Russ also spun off a sucessor chapter, forming the wolf brothers. he rejected the codex astartes, but he did split his chapter. truthfully if you look at it, almost all the surviving primarchs, except Dorn, cut a deal with Gulliman in one form or another

Russ only wanted the high numbers that successor chapters can generate, that's why he cut the Wolves in half as opposed to the ten or so successors that Guilliman made at the same time.
Russ wanted other recruitment worlds to supplement Fenris.

and your source for that is? we truthfully have no clue what Russ was thinking. myu gut feeling is he made a sucessor chapter mostly as sort of a token bit of cooperation that Gulliman could then take to the other high lords.

Horus > Guilliman/the Lion (depending on day and author > the rest... pre heresy. Guilliman edged the Lion on Strategy while the Lion edged Guilliman on tactics.

Post heresy, id put it as Horus > Guilliman > the Lion. Calth was a harsh lesson for Guilliman, it sharpened him into something more, while the Lion hasnt really had a kick in the pants like Guilliman did there.

As for Warmaster, it's pretty clearly Horus > Sanguinius > Guilliman as a distant third. Guilliman, at least, could be a politician. The Lion was too anti social, too brooding and prone to keeping secrets. Even then, with Horus and Sanguinius around, Guilliman and the Lion were never really in the running.

Edit: I always love that Angron quote. Nevermind that Guilliman had managed to make a multi system Empire before the Emperor even showed up, while Angron couldnt even take his own world. Corax managed to take his slave army and take over Deliverance!

Angron, who was going to be killed by mere humans. Guilliman managed to take Macragge after the coup into a multi system emprie, Angron couldnt even lead a bunch of gladiators made for battle to take his own planet. In fact, Nuceria ended up as part of the 500 worlds! Heck, Angron couldn't even get his own Legion to follow him until he had murdered the former master of the legion.

BrianDavion wrote:

 Dakka Wolf wrote:

BrianDavion wrote:

 Dakka Wolf wrote:

SomeRandomEvilGuy wrote:

 ChazSexington wrote:

Guilliman was described as the best logistician and organiser of the lot, not diplomat or leader. He was not good at diplomacy; even before the Heresy he'd alienated Alpharius, Lorgar, Angron, Perturabo, and the Lion, and then came up with the codex to piss of more Loyalist ones.

It fairness the stuff with Lorgar wasn't his fault and Angron was bitter and hated almost everyone. I don't recall Guilliman alienating Perturabo though. Breaking up the Legions was ordered by the High Lords of Terra so it's unfair to blame Guilliman for that.

As fro the Tesstra Compliance, Alpharius by his own admission deliberately dragged out a compliance so he could show off, resulting in far greater casualties among the populace they were trying to assimilate into the Imperium. Guilliman might not have been diplomatic about it but Alpharius' methods were definitely wanting.

Actually breaking up the legions was a decision made by each leader it's not something that can be blamed on Guilliman at all. Russ for example chose to use the order as toilet paper.

actually thats wrong. Russ also spun off a sucessor chapter, forming the wolf brothers. he rejected the codex astartes, but he did split his chapter. truthfully if you look at it, almost all the surviving primarchs, except Dorn, cut a deal with Gulliman in one form or another

Russ only wanted the high numbers that successor chapters can generate, that's why he cut the Wolves in half as opposed to the ten or so successors that Guilliman made at the same time.
Russ wanted other recruitment worlds to supplement Fenris.

and your source for that is? we truthfully have no clue what Russ was thinking. myu gut feeling is he made a sucessor chapter mostly as sort of a token bit of cooperation that Gulliman could then take to the other high lords.

Black Templars last Codex if memory serves. The Salamanders, Imperial Fists and Space Wolves almost incited a second civil war over not wanting the Codex or the chapter breakdown.

Lion El'Johnson - "Insult me again, brother, and theoretically I will punch you in your practical face"

Is this a real quote? Is Johnson really this much of a man-child?

 BlaxicanX wrote:

Lion El'Johnson - "Insult me again, brother, and theoretically I will punch you in your practical face"

Is this a real quote? Is Johnson really this much of a man-child?

He did spend most of his formative years in a forest. It doesn't hone your social skills. And I have the impression Guilleman isn't the nicest Primarch.

In fairness I imagine most of the Primarchs would be okay with settling things with violence. It's what they were made for and it's what they (travel to) do a large proportion of the time.

SomeRandomEvilGuy wrote:
In fairness I imagine most of the Primarchs would be okay with settling things with violence. It's what they were made for and it's what they (travel to) do a large proportion of the time.

it's also the snide remark about theoreticals and praticals, which is honestly not a bad way to approuch problem solving.

 BlaxicanX wrote:

Lion El'Johnson - "Insult me again, brother, and theoretically I will punch you in your practical face"

Is this a real quote? Is Johnson really this much of a man-child?

Sanguinius is probably the only Primarch who didn't act like a man-child at some point.

pm713 wrote:

 BlaxicanX wrote:

Lion El'Johnson - "Insult me again, brother, and theoretically I will punch you in your practical face"

Is this a real quote? Is Johnson really this much of a man-child?

He did spend most of his formative years in a forest. It doesn't hone your social skills. And I have the impression Guilleman isn't the nicest Primarch.

If by "forest" you mean catachan-esque death forest, then yes.

The Lion was a full grown man before he spoke his first words to another human being. He survived infanthood/childhood/adolescence, all those years you're developing your social skills, on a death world, killing warp beasts with nothing but his hands.

A consummate warrior. A brilliant strategist. The perfect hunter. All of the above. A oratory genius? Not so much...

Exactly. The Lion was the best straight up tactician.

I can accept that. He is essentially a borderline aspergers case in how focused he is on how he thinks things should be.

Put him in command of a cybernetica cohort, with a clearly defined battle objective, and he will do as well or better than any other primarch.

The reason he wasn't warmaster, and why making him a warmaster after Horus' treachery was a bad idea, is that he has essentially zero people skills and next to no ability to judge or allow for character.

In a game of chess -not an issue. In a civil war? He lurches from credulous to paranoid at exactly the wrong moment, reacts badly -even violently - to being questioned, when the things he's doing would be enough for him to see anyone else as a traitor (but he's loyal, so thats fine)

Ultimately, almost all the primarchs are 'the best'' in a given situation.

 Pilau Rice wrote:

SomeRandomEvilGuy wrote:

 Pilau Rice wrote:

But so had the Word Bearers, Iron Warriors and Alpha Legion. Horus had shown nothing but Loyalty to the Imperium. I think the problem is that in a time of uncertainty you shouldn't be trusting anyone with your WMDs.

None of three had been revealed as traitors yet. As far as anybody knew the Traitors had declared themselves openly. Trusting nobody would cripple you too and potentially cast aspersions on your own loyalties.

Exactly. Dorn's plan might have sucked in hindsight. But what options did he have really. Sending in 3 Legions to battle 3 Legions could have ended up being a stalemate that dragged on and on at the cost of the Legions themselves. How was Dorn to know that 4 of the seven had sided with Horus.

Well, Fulgrim told Dorn about Curze's visions of the future. Dorn had every reason to expect something like this.