Captain Marvel will be in theaters March 8, 2019. That's not too far away, but far enough that despite the years-long buildup typical of the Marvel Cinematic Universe (Brie Larson appeared onstage with her "fellow heroes" a year ago at SDCC, without a frame of film known to have been shot) very little is clear about its story, setting or even the background of its main character.

Some of that is owed to the challenges in adapting the character: The "Captain Marvel" of the film, Carol Danvers, is the seventh hero to carry that mantle in the comics; and her origins are so bound up in the convoluted history of the brand (to say nothing of the infamous "Rape of Ms. Marvel" storyline, which Marvel would prefer we all forget happened) that it was a foregone conclusion that the character would receive a significantly different backstory for the film.

But as of this year's SDCC, fans now have at least a few solid details to build their theories around: The film will be set in the 1990s, will involve a (still two-eyed!) Nick Fury, the shape-shifting aliens called Skrulls, and will incorporate elements of "The Kree-Skrull War," a famous 1971-1972 Marvel story that rates as one of the most influential comics of the Silver Age, and which prominently featured the original Captain Marvel as part of its sprawling narrative.

The story itself is a landmark, the quintessential early work of writer Roy Thomas - the most prominent of the first generation of 70s Marvel writers to originate as 60s Marvel superfans - and showed off his affection for the Lee/Kirby/Ditko mythos through the 9-issue story's weaving together of long-term plot threads not only from Avengers (the series where the story took place) but also Fantastic Four, Captain Marvel and Inhumans. In this respect, it served as one of the key ancestors of comic-crossover "maxiseries" like Marvel's own Secret Wars, The Infinity Gauntlet and Civil War as well as DC's various semi-annual "Crisis" events.

But what, exactly, was the story of The Kree-Skrull War? And how might a hero-filled crossover event from the early-70s fit into the plot of a single-hero (at least as far as we know) movie set in the 90s but made in the late-2010s? That takes some explaining - not just of the story, but of the players involved.

PRE-WAR: THE KREE

Ronan the Accuser in Guardians of the Galaxy

If you've seen the bulk of the Marvel Cinematic Universe movies (and at least one of the TV shows) you're already familiar with the Kree. They're a space-faring race of blue-skinned humanoid aliens who follow a techno-organic hivemind called The Supreme Intelligence and are really, really into war - Marvel's Klingons, essentially. In the comics (where they date back to Fantastic Four #65) they have one of the more complex and convoluted histories of any corner of the Marvel Universe, largely because their originally simple origin ("bad blue people from space") kept getting folded into the backstories of other alien/cosmic Marvel characters like the Inhumans (well after both had debuted) and the Celestials.

In the MCU, the connection between the Kree (whose most prominent MCU "name" figure was Guardians of The Galaxy nemesis Ronan The Accuser) and the Inhumans has already been established as of the second and third seasons of Agents of S.H.I.E.L.D., and largely reflects the relationship from the comics. Ever in search of new weaponry to fight their various intergalactic enemies (see below) the Kree experimented on prehistoric humans to create super-soldiers, resulting in a super-powered subspecies of humanity later known as Inhumans - the "modern" iteration of which are currently part of S.H.I.E.L.D's main storyline and the O.G. version of which will have their own series hitting at the end of the summer.

PRE-WAR: THE SKRULLS

Compared to the Kree, the Skrulls are a lot less complicated - particularly since they haven't appeared anywhere in the MCU yet. They were, supposedly, at one point meant to be Loki's henchmen in The Avengers, but were swapped out for the more straightforwardly soldier-like Chitauri. This was in part because of legal questions over how Marvel is able to use them as characters given that they debuted as villains in The Fantastic Four franchise, and are thus co-owned (in terms of movie rights) by Twentieth Century Fox.

The Skrulls are a green-skinned alien race distinguishable by their distinct ridged chins and ability to shapeshift into almost any other biological form - a power that Marvel has used to explain their way into and out of just about every kind of inconvenient plot point you can imagine. The first meeting of the Skrulls and the Fantastic Four ended when Mr. Fantastic tricked three Skrull advance-scouts into taking the form of (and then living out life as) a trio of common Earth dairy cows - and believe it or not, that's an extremely important detail.

PRE-WAR: CAPTAIN MARVEL

Mar-Vell and Captain Marvel

The original (male) Captain Marvel was an undercover Kree soldier named Mar-Vell who, after complications in his original mission, remained on Earth and adopted a superhero identity as "Captain Marvel;" fighting off alien threats (including those from his own people) alongside his ally Carol Danvers - who would later be discovered to have absorbed Kree Energy during a battle and become a hero in her own right as Ms. Marvel and, eventually, the seventh "official" Captain Marvel. Mar-Vell, meanwhile, later ended up gaining new powers (when Roy Thomas took over as writer) and entering into a "body-swapping" symbiosis with onetime Incredible Hulk sidekick Rick Jones.

Mar-Vell was created very quickly (even for them) by Stan Lee and Marvel in order to take advantage of a brief legal window wherein the rights to the unrelated mega-popular 1940s Captain Marvel had not fully transferred from defunct Fawcett Comics to DC. The character was never very popular, but in order to hold the trademark Marvel had to keep reviving him (or the name) every few years. Mar-Vell had his last self-titled original-run adventure in 1970, a little over a year before he re-appeared as a central figure in The Kree-Skrull War. This took place over nine consecutive issues of The Avengers which, because the concept of a full-on "maxiseries" hadn't yet taken complete shape in the comics medium yet, were more like a series of individual stories linked by events and characters.

"THE ONLY GOOD ALIEN..." (AVENGERS VOL 1 #89)

The story-proper begins in media-res with Captain Marvel back on Earth (after having been stuck in The Negative Zone and last seen there in Fantastic Four #109) confused and fighting Rick Jones and Avengers members Quicksilver, Scarlet Witch and Vision before flashing back to explain what happened: Rick, believing that the headquarters of the Fantastic Four held equipment that could be used to retrieve Mar-Vell from The Negative Zone (the way the duo's powers usually work is that they swap places between Earth and the Zone, unable to occupy the same universe at the same time) had broken into Reed Richards lab - triggering a distress alarm that was answered by the only Avengers who happened to be home at the time because Avengers Mansion, in the Silver Age, was basically a superhero hostel.

Following an unexpected encounter with Annihilus, a Negative Zone-based cosmic villain who's always kind of waiting by the door just in case things like this happen, it's revealed that Mar-Vell has been poisoned by Negative Zone radiation and will die unless Rick, The Avengers and a set of NASA scientists can cure him. Said cure works, but results in both Mar-Vell and the Vision being knocked out cold. This is noticed out in the stronghold of the Kree Empire, where Ronan The Accuser (who really, really dislikes Captain Marvel) is attempting a coup against his leadership and remotely activates a Kree Sentry robot on Earth to kill Mar-Vell while he's down.

"JUDGMENT DAY" (AVENGERS VOL 1 #90)

After the Sentry successfully abducts Mar-Vell to parts unknown, Rick Jones and the other the heroes are summoned to join three other Avengers (The Wasp, Hank "Ant-Man" Pym in his Yellowjacket persona and Clint Barton, aka "Hawkeye" but currently borrowing Pym's Giant-Man technology and calling himself "Goliath" - read it again, it'll makes sense) to investigate the sudden appearance of a tropical rainforest in the Arctic Circle. As it turns out, this is Ronan's doing: As part of his attempted takeover of the Kree Empire, he schemes to de-evolve Earth back to prehistoric form - and has already managed to turn Yellowjacket into an ape-man along with several other humans, the main psychological effect of which seems to be making them lust uncontrollably for the Wasp once she arrives on the scene.

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"TAKE ONE GIANT STEP - BACKWARDS!" (AVENGERS VOL 1 #91)

Ronan makes a mind-controlled Goliath fight the other Avengers, while Quicksilver and Rick Jones get Captain Marvel free and Hank Pym rediscovers his humanity. Everything gets cut short when Ronan gets word that Kree Space has been surprise-invaded by The Skrulls and heads back to fight - which sort of makes this the beginning of "the war," but also doesn't because they've technically always been at war. This is also the Avengers issue where the eventually long-running romance story between Scarlet Witch and Vision is set in motion, to be revisited for years to come, and arguably the arc that established the android Avenger as a permanent fixture of the team and the broader Marvel Universe.

"ALL THINGS MUST END" (AVENGERS VOL 1 #92)

The Kree-Skrull War was full of "big ideas" that Marvel would revisit in different forms for many subsequent maxiseries, and this issue dropped in one of the biggies: A U.S. Senator named Craddock is hopping mad about all this recent alien activity on Earth, and has launched a McCarthy-esque probe for "Alien spies" with a special focus on The Avengers themselves. This gets all "topical" when amped-up anti-alien protesters opt to trash Avengers Mansion while the heroes are in Washington testifying.

No sooner have they sent Mar-Vell, Rick Jones and Carol Danvers off into hiding than the Big Three (former, at the time) Avenger  - Captain America, Iron Man and Thor - show up more or less out of nowhere and tell the new(er) recruits that they're unhappy with their performance and are disbanding the team. In case you're wondering, Avengers membership in the Silver Age was effectively "whoever was staying at The Mansion at the time," so this is as close to a formal call to order as you'd expect to get.

"THIS BEACHHEAD EARTH (PART 1)" / "JOURNEY TO THE CENTER OF THE ANDROID (PART 2)" / "WAR OF THE WEIRDS (PART 3)" (AVENGERS VOL 1 #93)

The iconic image of The Kree-Skrull War is The Vision appearing suddenly before Cap, Iron Man and Thor and collapsing after shouting "Help me! Three... cows... shot... me... down..." It comes from the cover of this issue, and yes - it turns out he's talking about the cows who were actually Skrulls from way back in Fantastic Four #2, who attacked the "disbanded" Avengers at the farm where they'd stashed Mar-Vell and Carol Danvers in the guise of members The Fantastic Four. Also in this issue: Ant-Man shrinking down to repair Vision's circuits from the inside, a scene that will almost-certainly be recreated on film at some point. Oh, and the Cap, Thor and Iron Man who'd given the "disband" order in the previous issue were also these same Skrulls, while this "Carol" is actually the deadly Super Skrull - who uses all the confusion to abduct Mar-Vell.

While continuity nods had always been part of the Marvel Universe, reaching so far back to such a minor plot-point as the Skrull Cows was pretty extreme for the time. But Thomas knew what the older Marvel mainstays were still finding out: That there was a huge audience of ultra-devoted longtime readers (including teens and adults) like him who ate such details up - a conceit that now forms the core of the Marvel Cinematic Universe multimedia strategy.

"MORE THAN INHUMAN! (PART 1)" / "1971: A SPACE ODYSSEY (PART 2)" / "BEHOLD THE MANDROIDS!" (AVENGERS VOL 1 #94)

So what, exactly, was Super Skrull (at the time one of the most powerful villains in the Marvel canon) doing on Earth, apart from messing with the Avengers and Captain Marvel? He's here to destroy Attilan, the secret city of the Inhumans, as part of his people's war effort against the Kree. At the time this was new information, as the connection between the Inhumans and the Kree hadn't been fully revealed (read: invented) yet. Prevented from doing so by Attilan's defenses, Super Skrull decides to threaten Scarlet Witch and Quicksilver's lives in order to coerce Mar-Vell into building a superweapon back on Skrull Homeworld for him instead. Elsewhere, the Avengers fight a squad of Government-dispatched robots (the whole "alien oppression" thing is still happening) but get a change of plans when one of the Inhumans (Triton) shows up asking for help.

"SOMETHING INHUMAN THIS WAY COMES" (AVENGERS VOL 1 #95)

inhumans Old School

Short version: As happens on an almost monthly basis, Inhuman ruler Black Bolt has been ousted by his insane brother Maximus amidst all of this chaos, and could use Avengers help pulling things back together. Captain America, Goliath, the Inhuman Triton and Rick Jones opt to take care of this problem, while Vision, Iron Man and Thor go to space to settle up with Super Skrull. The Earth-based battle involves a trip to San Francisco to pick up Black Bolt (full name: King Blackagar Boltagon, lest you forget) and a relatively short battle to depose Maximus that mainly serves to get the Inhumans into the storyline - lest you be under the impression that the Marvel movies invented that kind of "Fancy meeting you here!" coincidental cameo. In the midst of all this, the Kree get hold of Rick Jones.

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"THE ANDROMEDA SWARM" (AVENGERS VOL 1 #96)

This would be where things get all Star Wars-ish (or, since Star Wars didn't exist yet, Flash Gordon-ish); with the Avengers borrowing a S.H.I.E.L.D. spaceship (S.H.I.E.L.D. has spaceships, because S.H.I.E.L.D. has everything) to go rescue Mar-Vell from the Skrull homeworld and battling through an armada to do so. Vision briefly loses his mind and nearly beats a random Skrull captain to death when he finds out they'd personally threatened Scarlet Witch's life - because, like any good 70s sci-fi android, Vision can do human emotions... just not very well.

Either way, they're almost too late. The Skrulls are in the midst of launching a plan that will destroy all life on Earth (this becomes specifically Goliath's job to solve) so that they can repopulate it - Earth actually being "destined" to be inhabited by their kind being a religious conviction in Skrull culture. The Kree Supreme Intelligence (which has only just wrested control over The Empire back from Ronan) also have a plan, which involves zapping Rick back to The Negative Zone to confront Annihilus.

"GODHOOD'S END" (AVENGERS VOL 1 #97)

So does this all end? Well, the trip to The Negative Zone and the skirmish with Annihilus unleashes "the full potential of the human race" in Rick's mind, and he uses it to conjure up projections of his all-time favorite superheroes from Marvel's pre-Marvel (re: Timely Comics) WWII-era comics - O.G. Captain America, Patriot, Fin, Angel, Namor, Blazing Skull and the original Human Torch - to bring the war to a standstill, immobilize and repel the Skrulls, rescue The Avengers and expose the head anti-alien Senator on Earth as (just guess) another Skrull impostor.

The personal melodramas between The Avengers and Mar-Vell also come to various ends, but most of them (including the fact that Goliath a.k.a. Clint is missing now) are left open to resolve in subsequent post-War storylines because Marvel wanted the story to be effectively wrapped at this point - though the whole thing would be revisited in (much) later stories to add details like how Rick's briefly-omnipotent powers actually work and Mar-Vell fathering a child with the Skrull Emperor's daughter during some period of down time.

THINGS TO COME

Captain Marvel's side in Marvel's Civil War II

Given how much... "stuff" goes on in The Kree-Skrull War and how many of the major details (Rick Jones, an already-existing Captain Marvel, all of the Avengers) won't be available for the 90s-set Captain Marvel movie, what could that film possibly be taking from this story (apart from, obviously, a war involving both Kree and Skrulls)?

Well, it's not too far removed from plausibility that Ronan might turn up again, death being relative in Cosmic Marvel. At least one of the alternate-dimensions/realities revealed in Ant-Man and Doctor Strange subbing in for The Negative Zone is probably also a decent bet, especially if they figure in whatever Carol Danvers new origin story turns out to be (alternately, they could explain how she'll eventually show up in the present for Avengers 4 without being around for all the other movies to this point.)  It also feels like the idea of a government "crackdown" on aliens (maybe not as public as in the comics) could fit in fairly logically, especially with S.H.I.E.L.D. and a younger Nick Fury (and maybe a younger Phil Coulson? Still-alive Peggy Carter? Tertiary space-traveling Guardians of The Galaxy bit-players?) already known to be in the mix.

There's no real way to be certain. But so long as Marvel continues to mine specific classic comics for their story points, the fans will likely never stop digging.

Next: What Does Captain Marvel’s ’90s Setting Mean for the MCU?

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