Imperium of Man v. Great Crusade

[Stravo]

Inspired by Ender's thread on just when is the Imperium of Man at its height it got me thinking. What if the Forces of the Great Crusade, right before the corruption of Horus were transported forward into the current 41st Millenium Imperium of Man and they had the mission of retaking Imperium space?

They are connected back to the past via a series of heavily defended wormholes (warp storms that the Great Crusade ships are immune to) and the Emperor of Man from the Past engages the current EoM in a titanic psychic duel that locks them both out of the fight.

Horus leads the Great Crusade Forces with all the Primarchs and their legions at his disposal. The "current" Space Marines will be unflappably loyal to the "current" Imperium of Man and will not defect thinking these Great Crusade forces are Chaos forces masquerading as the mythic heroes of the past.

Chaos and the Xeno filth decide to sit this one out and let the forces of the Imperium slaughter each other.

Victory conditions for the Great Crusade forces: Siege and take Holy Terra

for the Imperium: Repulse the Great Crusade fleets and kill Horus

The location of the wormholes are on the outskirts of Imperium space and thus no lightning strikes straight for Terra, Horus will have to cut a bloody swath through Imperium space.

What do you think would happen? Can the Great Crusade restore order to the Imperium and bring it back to the Golden Age? Will Horus lay siege to Holy Terra only this time on the side of the Angels? Will the current battle hardened geared for war Imperium teach these mythic heroes from the past a lesson in pain? How will the "current" Space Marines fare against their progenitors?

[Guardsman Bass]

I'm pretty sure that the Great Crusade forces, assuming they didn't run into nasty logistical problems, would dominate the current Imperium. I think the space marine chapters were actually far, far more numerous than the current 1,000 that you see in the Imperium. Plus, of course, you have the Emperor himself, who is no doubt a formidable foe for anyone in the Imperium who would choose to face him.

[Brother-Captain Gaius]

I don't think this is very clear cut. On one hand, the Crusade forces have all the Primarchs and a significant organizational advantage in its eighteen Legions. The M41 forces have a slight technological edge and from what we've seen of the Horus Heresy books, a vastly superior Imperial Guard. There are also a number of doctrines and organizations established in the wake of the Heresy and other events that M41 will have on its side, notably the Adepta Sororitas, the Officio Assassinorum and the Inquisition, who while not necessarily a huge factor in an all-out war, could wreak havoc with any Crusade reconnaissance and espionage.

Without external threats being a pain in the ass, the M41 Imperium can afford to mobilize quite a bit. So I think it comes down to whether or not Horus can get to Terra before a significant portion of the Imperium can be mobilized and sent to the front. If it really comes down to the wire though, it'll be interesting to see the M41 Imperial Fists (and perhaps the Black Templar) hold Terra a second time.

[Ford Prefect]

Without external threats being a pain in the ass, the M41 Imperium can afford to mobilize quite a bit. So I think it comes down to whether or not Horus can get to Terra before a significant portion of the Imperium can be mobilized and sent to the front. If it really comes down to the wire though, it'll be interesting to see the M41 Imperial Fists (and perhaps the Black Templar) hold Terra a second time.

Really, it'll come down to seeing how good Sol System's defenses are. How many ships can the guns around Terra take down before they can start dropping troops?

[Stravo]

I'm pretty sure that the Great Crusade forces, assuming they didn't run into nasty logistical problems, would dominate the current Imperium. I think the space marine chapters were actually far, far more numerous than the current 1,000 that you see in the Imperium. Plus, of course, you have the Emperor himself, who is no doubt a formidable foe for anyone in the Imperium who would choose to face him.

The OP does stipulate that the Emperor is neutralized since he is currently engaged in a titanic psychic struggle with himself. This is Horus' show.

Also I think the 41st Imperium's vast experience with Psykers might prove a tipping point since the Horus Heresy Novels I've read so far indicate a distinct lack of knowledge/experience with Psykers.

[Hawkwings]

I'd think that the "modern" imperium would win this one, mainly due to the Guard. I mean, most of the enemies the modern Imperium will be facing are going to be pretty bog-standard humans with even lower tech equipment than the current Guard. Against Marines they're not gonna be able to do much, but you can't conquer the Imperium with several million Marines, which is all that's going to be left when they get to Terra. Basically, everything the Crusade fleet has got, besides Space marines and the odd high-tech war machine, the Guard can take on and beat. They can even take out the odd space marine with missiles, meltas, plasma, and heavy ordinance. Plus they've got the numerical advantage. And Commissars, which are going to be critical in keeping the disciplined fire going.

Specialist forces: Sisters of Battle, Inquisitors, Assassins, and of course modern Space Marines are pretty evenly matched with the Crusade marines I would think. Perhaps a psychic edge to the modern specialists because of the years of study since the Crusade.

Primarchs are the wildcard. If they personally take the field in battle, better virus-bomb the planet. If you do manage to kill one though, think of the morale boost!

How do Assassins compare to Marines? And I'd be interested in seeing what a Culexus could do to a Primarch (if anything).

[Sidewinder]

I'd think that the "modern" imperium would win this one, mainly due to the Guard.

Horus had a lot of Titans at his disposal, didn't he? So if the 41K Imperium can't deploy a comparable number of Titans in time, the Imperial Guard is going to be ass-raped by the walking cathedrals.

Besides, Horus had the Imperial Army (precursors to the Guard and Navy) on his side. (Source: Wikipedia.) How would 41K Guard fare against 31K Army?

[Sidewinder]

I just remembered: Horus had command over 18 Space Marine Legions during the Great Crusade, versus the 41K Imperium's command over the chapters formed from the nine loyalist Space Marine Legions. It seems that the 31K Space Marines outnumber their 41K breathren, which means the 41K Space Marines are going to be overwhelmed. (I may be wrong-- comments from someone with relevant data?)

[Fingolfin_Noldor]

I'd think that the "modern" imperium would win this one, mainly due to the Guard.

Horus had a lot of Titans at his disposal, didn't he? So if the 41K Imperium can't deploy a comparable number of Titans in time, the Imperial Guard is going to be ass-raped by the walking cathedrals.

Besides, Horus had the Imperial Army (precursors to the Guard and Navy) on his side. (Source: Wikipedia.) How would 41K Guard fare against 31K Army?

Aren't some of the Baneblades configured to kill Titans? Or can they only kill the smaller varieties.

[Sidewinder]

Aren't some of the Baneblades configured to kill Titans? Or can they only kill the smaller varieties.

According to Wikipedia, yes.

Shadowsword
Weaponry: Volcano Cannon, two sponson-mounted, twin-linked heavy bolters.
Role: Tank destroyer-style Titan-hunter
Details: The massive size and energy requirements of the Volcano Cannon preclude the Shadowsword from mounting any other significant weapon. Unlike the Baneblade which fulfills a general purpose on the battlefield, Shadowswords are used in a specialized role with their main armament best being used against war engines and titans. The single Volcano Cannon is one of the strongest anti-armour weapons in the 40K universe.

Stormblade
Weaponry: Plasma Blastgun with co-axial heavy bolter, two turreted lascannons, two sponson-mounted twin-linked heavy bolters.
Role: Tank destroyer-style Titan-hunter
Details: One of the many 'counterfeit' Shadowsword variants, all of them replacing the Volcano Cannon with some other Scout Titan weapon. Though less powerful and having a shorter range, the Plasma Blastgun is cheaper and consumes less energy than the Volcano Cannon, making the Stormblade more easily produced.

The article doesn't say WHEN these Baneblade variants were produced, however. It's possible Horus will also have Titan-hunters under his command.

[Hawkwings]

I just remembered: Horus had command over 18 Space Marine Legions during the Great Crusade, versus the 41K Imperium's command over the chapters formed from the nine loyalist Space Marine Legions. It seems that the 31K Space Marines outnumber their 41K breathren, which means the 41K Space Marines are going to be overwhelmed. (I may be wrong-- comments from someone with relevant data?)

well, a Legion was about 100K Marines, right? And the stated size of the modern Imperium's Marines are 1000 x 1000 = 1 million. But not every chapter follows the codex, and we have chapters like the Black Templars that have somewhere over 3000 Marines, just all scattered around.

So, about 1,800,000 Marines vs somewhere around 1,100,000 Marines? That's not too bad, considering tech advances since then. Also, modern Marines would have experience fighting Marine enemies, while the Crusade Legions would not.

What's the average experience level of a Legion Space Marine? As in, years being a Marine?

How would 41K Guard fare against 31K Army?

Weren't they still using autoguns back then?

The navy would probably get beaten by the older/better ships, but I'm fairly confident that on the ground, the 41K Guard beat the 31K Army.

[Brother-Captain Gaius]

What's the average experience level of a Legion Space Marine? As in, years being a Marine?

Most of the Legions would still have proto- and first-generation Marines in them from the conquest of Terra and the Crusade prior to finding the Primarchs, so while there is a definite experience base there, the most experienced Marines will be the least reliable and of a clear-cut previous generation than the bulk of the troops (which as we've seen in the Heresy novels does cause friction and other issues).

Contrasted with the post-Codex Chapters who tend not to have that generational divide so clearly pronounced (since they've been doing things the same way for 10,000 years), as well as much longer histories and accumulated experience. First Company veterans are easily as old and probably older than even the Crusade's first generation Marines (who would be about 200-250 years old if I'm not mistaken?), so the experience advantage definitely goes to M41's Astartes.

[Ritterin Sophia]

I just remembered: Horus had command over 18 Space Marine Legions during the Great Crusade, versus the 41K Imperium's command over the chapters formed from the nine loyalist Space Marine Legions. It seems that the 31K Space Marines outnumber their 41K breathren, which means the 41K Space Marines are going to be overwhelmed. (I may be wrong-- comments from someone with relevant data?)

You're forgetting that the Grey Knights aren't a Codex Chapter, and the fractured nature of the Black Knights keeps the Inquisitorious from knowing their full numbers, and I can't remember if the Deathwatch is considered a chapter of it's own or what, for all we know these two alone could make up the extra marines required.

Then there's the fact that the 41st have some things the 31st don't. I believe the Mk 8 Power Armour has more armour plates to protect the cables and respirator from fire (both were left unprotected in the Mk 7), as well as better protecting the kneck. The Land Raider Crusader is completely missing from their inventory. Whilst the Imperium may be rather stagnant in terms of technology, it is not completely so.

Though it would be amusing to see Bjorn the Fell-Handed fight against himself and Leman Russ.

[white_rabbit]

Off the cuff, I'd go with an initial massive spread of victories for the Crusade force, but eventually the tremendous weight of numbers of the Imperium in both manpower and very likely, fleet assets, along with the current state of affairs in 40k making for a rather horrifically intense and drawn out conflict with waay too many variables to even make an educated guess about.

I don't think a decapitation strike at Terra would be a fantastic idea, it'd probably be like sticking your dick into a live socket, it doesn't matter how big it is, nothing good will come of it.

Horus had a lot of Titans at his disposal, didn't he? So if the 41K Imperium can't deploy a comparable number of Titans in time, the Imperial Guard is going to be ass-raped by the walking cathedrals.

The Adeptus Mechanicus have actually gotten rather tooled up militarily since the Heresy era, the Imperial Guard would be getting support from both Titans, their own superheavy platforms, and the Ordinatus Major and Minor, both of which are toting Titan and Superheavy Titan weapons. The key difference as far as Guard superheavies is that the Imperial Army fielded them much more often in large formations, while the current IG parcels them out. (although they do still have entire Heavy tank regiments etc that take the field)

How do Assassins compare to Marines? And I'd be interested in seeing what a Culexus could do to a Primarch (if anything).

In Wolfblade, an assassin of unknown temple (he used a super rare poison dart gun though, so there is an obvious inference there) was rather a bit faster than Ragnar, a space marine noted for his reflexes and speed in combat. He was also strong enough to give Ragnar a bit of a surprise, but ultimately not strong enough to wrestle a Marine.

I think if he had a power blade, or some other weapon, he'd have killed Ragnar effortlessly, but with just a dart pistol and his bare hands, he was a bit stuck, and eventually got mangled.

Vindicares obviously can destroy tanks with their rifles from 10km away, so its not a problem for them to kill your average marine, Eversors are well equipped to take on marines and could kill the average marine pretty neatly.

Callidus are equipped with weapons that can canonically kill Primarchs, so I think they might be okay.

Culexi might have a bit of a problem unless the target is psychic, and really powerful psykers can kick the shit out of them.

Heh, that reminds me, the best way to deal with the Blood Angel is to kill lots of his Marines, the big poofter can't cope with it

[Teleros]

In Wolfblade, an assassin of unknown temple (he used a super rare poison dart gun though, so there is an obvious inference there)

I believe think the Venenum temple is the one specialising in poisons.

[Skelron]

I think in the end the tipping point is that, for all it's horridness and flaws, the 41st Imperium is better suited for the universe ofthe 41st Millienium. Their is fear of the Warp, knowledge that dark things crawl out there, and want to deour the soul.

The great Crusade was a dream, it was glourious and bright, and an attempt to herald in a new age, and yet it was also built on a lie, sustained by (Willful) ignorance to a dangerous level. The question is not will they win, the question is will they still have the drive to fight when faced with over-whelming evidence that the Crusade is a lie, that the Imperial-Truth is a lie.

[NecronLord]

One interesting thing to consider: 41st Millennium Astropaths and Navigators have got to contend with a lot worse, as far as we know, during the Heresy, warp activity skyrocketed and stayed up. Pre-heresy equivalents will never have experienced the like. 41st Millennium ones sent into the past will think they've died and gone to heaven.

[AbyssalDaemon]

My vote would go the 41st simply becouse there's no way I can actully see other side being able to take Sol which is by this point the most heavily fortified area in the entire galaxy, Hell they have their own FLEET for the system and almost all the major player IoM have a small fleet their as well too make matter worse.