Last night came the shocking announcement: Robert Downey, Jr. will star in 'Captain America 3' alongside Chris Evans, kicking off the Civil War storyline in the Marvel Cinematic Universe. But, what exactly is the Civil War storyline and what does it mean for 'Captain America 3,' 'Avengers 3,' the Infinity Gauntlet plans, Spider-Man and the rest of the Marvel Cinematic Universe?! (Whew!)

What is Marvel's Civil War?

Civil War is one of those classic comic book crossover storylines that was published in 2006-2007 in a seven-issue limited series written by Mark Millar (while also running through comics like Black Panther, New Avengers, The Amazing Spider-Man, Fantastic Four, Captain America and Iron Man). The basic gist of the story will be familiar to those who've seen the recent 'X-Men' movies: like the Mutant Registration Act, which has provided much of the conflict in the X-movies, Civil War revolves around the "Superhuman Registration Act." The act would require anyone with superhuman abilities to register with the government; not so they can be shut down, but so that they can receive proper training and essentially become government employees. While superheroes like Iron Man, Spider-Man, Captain America and others debate the merits of the SRA, the act was swiftly passed after the New Warriors, in a battle with Nitro, accidentally leveled a city block, killing over 600 civilians, including an elementary school.

Tony Stark, previously against the SRA, was now a strong supporter of the movement. Spider-Man even joined his side, revealing his secret identity in public. Captain America led the anti-SRA movement, a group called The Secret Avengers. As tensions escalated, Captain America met Iron Man in what was supposed to be a peaceful discussion, but used a device to disable the Iron Man armor, punching Tony Stark and starting an all-out superhero brawl. Yes, 'Captain America 3' will be an Iron Man vs. Captain America movie.

How Will This Work in the Marvel Cinematic Universe?

While the Civil War comic storyline was epic in its scope, reaching across a multitude of comic titles, you shouldn't expect the same in the Marvel Cinematic Universe. Think of what Joss Whedon is doing with 'Avengers 2'. While the film is subtitled 'Age of Ultron' the actual movie is only loosely based on the crossover storyline from the comics. We'd expect that same approach here. Don't expect the Civil War storyline to dominate the next five or six Marvel movies. Think more along the lines of 'Captain America: Civil War' with the story being told in one contained film with ramifications that will impact future Marvel movies.

(While the New Warriors incident triggered the SRA in the comics, it will be interesting to see what Joe and Anthony Russo come up with as the inciting factor in the film. If we had to guess? It'd be Scarlet Witch related.)

One film this will specifically impact is 'Avengers 3' as we've heard the rumors that that film's lineup will be completely different. At the time, we speculated on an 'Avengers 3' without Iron Man and Captain America and now we know why Captain America and Iron Man will likely not be a part of that film. In the comics, Tony Stark retires to become the new head of S.H.I.E.L.D. and Captain America...

Will Captain America Die?

The Civil War storyline ends in the comics with the death of Captain America, shot by Crossbones and a hypnotized Agent 13/Sharon Carter. The death of Captain America was later explored in a comic series titled "Fallen Son." Both Crossbones and Sharon Carter have been confirmed as returning for 'Captain America 3' and Badass Digest is reporting that, for at least a certain time, the working title of 'Captain America 3' has been 'Fallen Son.' So, is Marvel really going to kill off Captain America?

Probably not. He didn't even really die in the comics (as superheroes never do). The gun fired by Sharon Carter actually froze him in space and time at the moment before his death. He was sorta bouncing around time and eventually regains control of his body and...well, it's pretty complicated and we just don't think it's something Marvel would want to attempt in their films. More likely, Captain America will go off the grid and disappear. The final Iron Man vs. Captain America battle ends with Captain America about to deliver the final blow to a beaten Iron Man before he looks at the destruction the fight has caused and surrenders. We can imagine him escaping custody and essentially sitting out 'Avengers 3' before he's recruited to return for the big massive 'Avengers 4: Infinity Gauntlet' movie.

What Impact Does This Have on Thanos and the Infinity Gauntlet Storyline?

Not a ton. We still expect Thanos to be the big bad of this overarching storyline with 'Avengers 4' culminating in a major battle against him. But, we need to get to that point first. What Civil War does is it allows The Avengers to become vulnerable. They're not the all-powerful superhero team. They're friends at the beginning of 'Avengers 2' but those friendships and alliances will be severely tested through that film and over the following films. The events of Civil War, and the battle between Iron Man and Captain America will result in a weakened superhero team, allowing Thanos to make his move. Then, ALL the Marvel superheroes will have to reunite for that epic 'Avengers 4: Infinity Gauntlet' movie to stop him. So, Civil War isn't replacing Infinity Gauntlet, it's just one of the small parts leading up to it.

Doesn't Spider-Man Play a Big Part in Civil War?

Good question. Yes, he does. As we mentioned before, Peter Parker sides with Iron Man and has a very public outing of his secret identity. Recently there have been rumors that Sony and Marvel were working on a way to get Spider-Man slowly worked into the Marvel Cinematic Universe. What if their plan is to test the waters with a Spider-Man cameo in 'Captain America 3,' essentially mirroring the bit from the comics? It would be a small step towards a larger plan, but would allow for some minor crossover into the Marvel world, and would give Sony an exciting way to relaunch a character they have no idea how to work with in their own universe. It's still a longshot, but if all the rumors are true, this is a way for it to happen and to make sense.

Where is Hulk While All This is Going On?

Here we go again. Planet Hulk.

One of the big events that starts the call for the Superhero Registration Act in Civil War is Hulk's rampage in Las Vegas, which leaves most of the city destroyed. Hulk goes into exile, but Tony Stark and Mr. Fantastic trick him onto a satellite and send him through a wormhole to exile on a far away planet. So, while the entire Civil War is going on, Hulk is fighting gladiators on Sakaar.

We have been told repeatedly by Joss Whedon, Kevin Feige and James Gunn that Planet Hulk is NOT happening in the movies, despite frequent and reappearing rumors. And, here's more fuel to add to the fire. If the 'Avengers 2' rumors are correct, it could very much explain how the SRA gets started, why Hulk is gone and, yes, even start up that Planet Hulk movie noise again.

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