A space marine legion appears on the door step of mars demanding to gain access to the Librarius Omnis to reclaim it for the imperium of man.
What would mars do?
Fucking wreck their shit, of course.
Even if this Legion were one of the bigger ones, on its own it'd be no match for the millions of Skitarii that would undoubtedly be guarding Mars, whole Titan Legions, and all the Space Marine chapters or Guard regiments that would be willing to join in the fight - and lets not forget that Mars produces the absolute best stuff, so they would not be fucking about.
Worst case scenario, they could just open the vaults and see how this random space marine legion enjoys having thousands of crazed machines up in its business.
Send a communiquee out
"First chapter that gets those bums away from our doorstep gets a free landraider" 15 minutes, and the biggest inter marine battle after the Badab War later, the invading space marine legion is slaughtered with no survivors.
>"First chapter that gets those bums away from our doorstep gets a free landraider"
>Magi around the galaxy start using this and similar things to lure in Astartes chapters to do their bidding
>Sometimes the tech isn't even useful, it just looks old
>A space marine legion
Is this a trick question?
It would be a fun rampage for all of a day or so, and then reinforcements from Terra would arrive. Probably some Grey Knights as well, and whoever else happens to be hanging around throughout the Sol system with time on their hands.
Alternatively, if they really were the original untainted organization they claim to be, imping some time-jump warp shenanigans, then there'd be a surprise techno-priest pile on the Primarch. This would be quickly followed by the scenario above. Not a problem as long as they get their manipulators on that Primarch. As for all the rest, well, they can make more space marines, so ...
>legions are strong and vast
Why do I find this phrasing so funny?
The only legions are fucking chaos though, because Emprah realized having only 20 armies of Spess Mehreens was retarded, so they wouldn't be trying to reclaim shit for the Empire, and if they actually got that close to Earth the nerd army would be the least of their problems. They'd have billions of troops on their asses in minutes, and an entire segmentum fleet to deal with.
One does not just approach Holy Terra.
Oh. Well then.
It would be a fun twelve hour rampage, followed by a twenty four hour curb-stomp. Followed by a query from Terra: "What's with all the explosions? Did something just happen?"
"Game over. Oh, and, if you could spare a discreet Inquisitor, have him pay us a visit. We have a few questions he might wish to purse."
Honestly I don't even think it'd last that long. This IS Mars we're talking about, not some backwater with IDFs with rocks. Mars is so built up I'd be more surprised if the marines could even get to their destination before being stonewalled by giant robots and tech priests.
Implied by OP the intruding Chapter has *complete* surprise. I also think the tech-priests would not wish to trash the cyber-hood, so they'd go about it with some restraint.
It would still be a curbstomp.
A Legion proper would be a serious problem. Mars would still win on its own, but overwhelming reinforcements would start showing up in orbit in a day, at most. Even if they did not ask for them. Weather Mars could easily beat that Legion on it's own isn't really relevant. Beaten they would be.
Why? They messed with the wrong Martians, and Astartes aren't much for diplomacy. Talking is for when you're peaceful enough to want to avoid bloodshed, or desperate to not fight and lose.
Hm according to the lexicanium its a huge arse ancient library
This legion is decimated in minuites by whatever old cannons and shit they have laying around
They are bound to have at least 1 dark age planetary defense system on planet somewhere. And if the legion are already on the surface they will be torn apart by thousands of turrets.
Mars is probably one of the best defended places in the imperium.
What with the Treaty of Mars and all that, isn't the Mechanicus technically its own empire overlapping and cooperating with the Imperium?
I don't think they have to take shit from anyone when it comes to Mars.
They aren't even going to pretend to be diplomatic while getting their forces in position to take less casualties in the fight ?
They aren't even going to 'ask' the High Lords to tell this legion to fuck off ?
Not even when the legions response to such an order will either make them stand down or clearly show to everyone that they are blatant traitors ?
Remember that tech priests make the average robot look like a spin doctor.
You'd be lucky if their communications had anything more to them than "GET OUT, CHAD MARINE REEEEEEEEEEEE"
Fuck no, those marines are getting fucking immolated. You forget that the fabricator general of Mars is also a high lord of Terra in his own time, any assault on Mars will immediatly bring the full might of battlefleet solar to it's aid.
Mars is the second most heavily defended planet in the galaxy, situated in the most heavily defended solar system in the galaxy. These marines wouldn't even make it past Saturn, let alone all the way to Mars.
This is mars there not going to have many auctual people in the fight the amount of turrets that must be covering that planet is insane.
I suppose depending on whos in charge at the time theymight delay for a few minuites but that does run the risk of them sneaking in.
So I guess it depends on who you end up talking to.
Either way those marines are fucking dead.
Yeah, they might have a bit of a problem with the sheer amount of shit the Sol system has.
Mars is...Mars. Jesus Christ I'd had to see the sort of guns it's got pointed at space.
There are entire moons that are now battle stations.
A space marine chapter calls it home
3 SOB Orders.
And whatever the guard presence is on Earth itself.
Even a Legion is going to have trouble with that.
It was *not* the Emperor that split the Legions. It was Gulliman.
Only one of the first fouding chapters is legion-building; the Dark Angels.
The Ultramarines are not Legion-building. They *do* hold posts in Ultramar not normally permitted to Space Marine chapters, but their successors do not answer to the command of Marius Calgar, nor would Calgar seek to have them do so. It was their precious spiritual liege who split the Legions in the first place.
All Ultramarine successors for a council headed by Ultramarines. they ARE legion-building.
also there are Blood Angels, who are bound with their successors by the secret of Black Blood Rage Thirst whatever that emo shit is called, so they all answer to Dante in the end.
then there are Black Templar, who are independent from Imperial Fists and not really Legion-strength, but still twice or thrice larger than your regular chapter.
The Fabricator-General might well call in some chits in the Senate Imperialis, but I think it's more likely to be for something in the form of
"[Chapter] and those of their successors who have followed them in unlawfully approaching the Sol System in open rebellion against the Imperium, in violation of the Codex Astartes, the Treaty of Mars and their fealty to the Emperor and his licitly appoint regents, the Senate Imperialis, are hereby declared EXCOMMUNICATE TRAITORIS and permanently attainted as traitors, renegades and heretics."
"Would you please back down chaps?"
It's like crossing the Rubicon; you come to Sol as a Legion, you are ending up either as the new Regent of Terra or as corpses.
I wouldn't trust space marines to do that. Once the tech gets more complicated than a bolter they have no idea what they're looking at.
Sure, they'd probably wipe out a number of infernal intelligences and corrupt machines that are skittering around down there, but they'd probably also destroy a number of priceless useful artifacts that happened to beep while a jumpy scout was walking past.
I ain't got the actual sauce, but part about Ultramar senate looks trustworthy and probably comes from some Ultramarine codex, I reckon.
>Second Founding successors.
THAT is massively more plausible. That's be 24 Chapters or 24,000 marines.
Which is...a lot of marines, but not quite what I'd call a Legion.
Whereas, all Ultra successors would be something on the order of 666,000 marines. And that's a legion and then some.
Don't be foolish. The most loyal chapter in the history of the Imperium which has never transgressed in any way whatsoever would never engage in such a blatant violation of Imperial command.
The point would be moot. If two-thirds of all Marines (and given the diversity of Ultramarine successors, we're talking, effectively, Space Bat mind control to them pointed the same way), abandoned their posts to try to take Mars and Mars called in all it's various favours to hold fast, the winner would be Abaddon the Despoiler, cutting a path to Terra as a dozen different front-lines collapsed at once.
>the winner would be Abaddon the Despoiler
Neh, it's Abaddon we're talking about. He'd declare a Black Crusade to capture Lion El'Jonson's favorite mug or something irrelevant and then bugger off back to the Eye once he has it, declaring victory.
After defeating the billions of skitarii and servitors the priests vomit at them, the multipule full titatn legions permanently stationed on mars, all the various segments of the imperial navy stationed in the Sol system, and the billions of guardsmen that immediately deployed, the space marines begin fighting their way past the daemon engines and pre-fall abominable intelligences that infest the bowls of the planet whilst their rear guard hold off the steadily growing tidal wave of reinforcements. Finally, after days of grueling battle, the last handful of survivors make it into the Librarius and hail victory. They commence a search and find nothing of great value. In the exact spot where their librarian had seen a shining golden beacon in the vision that led them here, they find a depression in the dust as if something large was moved quite recently, footprints matching very old power armor patterns, and a pair of dead traitor marines who have been shot in the back with a plasma and bolt pistol, respectively. Then they get eaten by haunted robots.
coming soon from the black library.
You want the Librarius Omnis?
Ask a certain Chapter to get it.
They once defeated a whole Hive Fleet with nothing more but a single Force Commander, a 4-man Tactical Squad, a 3-man Assault Squad, a 3-man Devastator Squad, a 3-man Scout Squad and a Dreadnought.
I'll have you know that this Librarius Omnis was gifted to our chapter by the Mechanicus. Very generous people, those tech priests.
>Vandire was betrayed by the SoBs
It was only a matter of time. And that was only a few Chapters.
2/3 of all Marine Chapters would shit down Mar's throat. 6000 Marines is considered an almost unstoppable force.
Mars is mostly a shit pile. Significantly less Marines have taken down daemon worlds, tomb worlds, hive fleets, sectors of space. Mars would not have any chance.
Mars during the Heresy was mostly an internal affair, and five Legions averaging ~100,000 Marines each is less than 667,0000 Marines.
Even Terra only held there becuase they had their own hundreds of thousands of Space Marines, Mars would have none in this scenario.
Mars has a space station surrounding the entire planet, which is covered in guns.
Then the surface of the planet is covered in guns. The parts which aren't covered in guns are covered in radiation, toxic waste, and mad robots.
The bits which aren't inhospitable wasteland are basically hive cities made out of guns, most of the fun shit is underground, which is full of robots covered in guns.
Mars is basically 90% guns at this point.
>then there are Black Templar, who are independent from Imperial Fists and not really Legion-strength, but still twice or thrice larger than your regular chapter
They got retconned into 1005 marines
A chapter would get wrecked fast. Mars is the second mostly heavily defended place in the galaxy, filled with skitarii who have more deadly tech than guardsman in addition to being tougher
Then you get titan legions. The fleetness orbital defenses, myrmidons, Knights, thallax, ordinatus, etc
>how do they fight the urge to incinerate all Mechanicus?
By playing politics and respecting the essential "agree to disagree" beliefs of the Ecclesiarchy and Mechanicus. They need what Mars provides, and they're willing to overlook their particular brand of the Imperial Cult in order to deal with real heretics. The Machine Cult has been deemed an "acceptable" version of the Imperial Cult for political purposes.
Then how do you explain the current lack of Caliban?
Shit, son. Luna IS Gun. No, it's not guns, or made of guns, it's apparently one insane orbital weapon that doubles as real estate. You have the Sol fleet, and the Saturn pickets alone are enough to annihilate damn near anything. There's just too much weight of fire that can be brought to bear. If it's truly Legion -vs- everyone else, no matter if tens or hundreds of thousands, the rest of the Imperium will annihilate them in an eyeblink.
I don't even think of it as a retcon. At that time, the Black Templars were only slightly bigger than Codex. That doesn't mean they haven't been much bigger than codex (and quite possibly beneath codex strength after particularly brutal Crusades) in the past, just that they were'n't much overstrength during the Third War for Armageddon.