The outer defensive lines were more comparable to German WW1 trenches to my understanding, fortified trenches with bunkers and artillery support, as opposed to a Maginot style field of heavy fortifications, armoured gun emplacements, mobility restricting obstacles and such. Gorgons could drive right up to the first trench lines after all, which would have been pretty difficult if there were proper tank traps and similar there.
Yes, but all those are covering each other. The outwards ones are being covered by artillery and giant fucking guns from fortress, so while technically it's easier to walk into the outer line, since it's not like, giant walls, but you are constantly shelled by the guns on giant walls and artillery in more trenches, and generally there's so many fucking fortifications.
Things is there's plenty of things the DK did wrong on Vraks, some tactical and some just issues with poor equipment choices for the assault.
Sure, they do fuck up, like everyone does. You can't wage war and expect your plan to be 100% flawless, but in general they were amazing at it.
Holding tanks in reserve until breaches were already made in the outer trenches rather than bringing armour that could help suppress trenches with machine gun fire or explosives or burn them out with flamers is a pretty poor idea, a few close quarters armed Leman Russ tanks or Hellhounds coming up in the cover of the Gorgons could have incinerated whole trenches in minutes rather than forcing the DK to clear them by hand and face the heavy numbers of defenders and close quarters heavy units the DK lacked but the traitor's had in spades.
Tanks are expensive. Men are not. Also, Gorgon assaults are covered by heavy artillery shelling. Few tanks don't really make that much difference, and it only endangers them.
Poor communications equipment is another issue, they didn't even issue their elite grenadier units anything better than a squad vox unit, which was why they were so reluctant to try more complex assault plans, if they'd issued some of their elites with microbeads, even just the sergeants, they could have coordinated nighttime assaults easily for all the trench assaults rather than considering it too difficult to try.
Someone is gonna have to go there and pluck those microbeads out of their ears. Presumably microbeads, being much lower power than vox units, have been interferenced by weather and the sheer amount of ground and explosions flying in the air.
They also sent tons of Kriegsmen fresh out of training, they'd never seen any planets other than Krieg and had no real combat experience and were just thrown into a battle on alien terrain in incredibly hostile conditions they had never encountered.
Uh. So, like, Imperial Guard does regularly?
Sending a force from multiple worlds that were all experienced in actual combat would probably have been a better use of men than selecting all of them from one world if that force requires new recruits to bulk it out. Vraks was not a good place to get your first live fighting experience.
Experienced Kriegers are kind of a weird combination of words. Also, that is assuming you have the comfort of doing that, which Imperium presumably doesn't.
Air support does not seem to have been present at Vraks from what I can find,
Marauder bombers played a quite big role in the siege, and there were tons of other stuff.
and the original army list for the DK didn't have access to any fliers (though at the time they were all classed as skimmers anyway, but it was still a major distinction between them and normal IG.)
Lore =/= tabletop. And again, what Imperial Guard regiments mainly use is stuff like Valkyries, while what was used was mainly heavy air support like Marauder Bombers, Thunderbolts and such. I am not aware if stuff like that was in IG lists back then, but in terms of fluff those were certainly used at Vraks.
Granted this may have been due to the insane weather storms on Vraks making heavy use of fliers difficult, but the traitors still managed to use the odd thing like Arvus Lighters to ferry troops around, so I think it's more just that Kriegers don't care for air support due to their military traditions.
Kriegers, again, have absolutely no say in getting air support or not. If there weren't any fliers (and there were), blame Imperial Navy.
Most of this stuff can be blamed on Commander Zuehlke, his command staff and the Munitorum more than the field commanders, but I still feel the reason Vraks took so long and became such a mess was because the DK weren't actually the best choice for the assault, they aren't great with using mechanised and armoured forces, lack speed and are defined by squandering resources in futile assaults due to their penitence complex (an actual part of their regimental summary, they're Chenkov: The Faction.) In a war where time and available manpower isn't a factor those are fine, but when you have a set timeline to finish things in and only so many military assets to spare you need a regiment with a bit more speed and coordination to minimise losses relative to progress in taking the objective. Cadian/Steel Legion style mechanised regiments supported by rapid armoured assaults could have negated the advantages of the outer static defences in much the same way trench warfare was largely supplanted by tank warfare in the real world.
Mechanized regiments would be destroyed by enemy cannons. That stuff killed ships, the only reasonable option was a siege. Siege, where you hammer the enemy with as much artillery as you can, and what is left there is land that is horribly hard to traverse with vehicles. I mean, sure, if they deployed like 100 Imperator titans on Vraks, then that would be over pretty fast, but can't have everything, can we?
So if Big E was the result of practically every shaman psyker merging, and we can assume that the average shaman is 'modestly' to 'Black Ship hunts you down when because they feel the backlash of your birth' powerful, how did E get even strong enough to imprison the Void Dragon when he did? He was just a sexy, sexy balt then with a modest warband, right?
Okay, so, humanity is psychic. There's bunch of shamans, maybe like few hundred or thousand, and people are being sometimes eaten by enslavers and shit, so shamans decide to bunch up and do a ritual to focus humanity power in one being. Boom. There are no psykers for next what, 35000 years? Emperor, as a being, is filthy powerful, because his existence is essentially humanity trading becoming something akin to Eldar in terms of psykers to just focusing all that shit in one person. Presumably only now, with Emperor losing a bit of grip, humanity starts getting more and more psykers, which are then usually delivered to him anyway.
It'd be hard to frame "the collective reincarnation of all of humanity's psychic mutants fought a magic metal dragon wizard in 1300s Libya and hauled it off to Mars without anybody noticing" any other way, to be fair.
Quite a few sources imply legend of Saint George is people explaining Emperor fighting Void Dragon. I mean, think about it, in various versions there's stuff about statues possessed by Satan, then there's the Dragon, and all that shit. GW toys with history quite a bit, like placing Emperor's birth in Anatolia, and historically, "soon" after Hittite Empire appears. The royal symbol of Hittites was a double-headed eagle.