In the United States, a Super-human Registration Act is passed, which decrees that all Mutants or Super-Humans must register with the government, giving all personal information, as well as powers.
Overview of Key events of the civil war. Note: Since the Civil War arc is so massive in its scope, some of the information included here will be from comics leading up to the actual arc, and comics that detail events that occur directly afterward.
Tony Stark and Peter Parker go to Washington D.C. to try to refute the Super-human Registration Act. Peter is to act as Tony's eyes and ears. However, things go awry and an assassination is plotted against Tony by Titanium Man. However, it is later revealed to the reader that Iron-Man (Tony Starks) plotted the assassination. His motive was to show the need for a Super-human Registration Act, so in fact he is playing both sides. When Captain America is approached by SHIELD to see if he could neutralize all of those against the Super-Human Registration Act, he refuses and has to run out after they try to shoot him down. Captain America is denounced as a criminal by the President, and he is ambushed by S.H.I.E.L.D, yet still escapes.
The New Warriors, a group of mutants with their own TV show, trying to get higher ratings ambush Nitro, Coldheart, Cobalt Man, and Speedfreek. But Nitro, powers amplified by Mutant Growth Hormone, sets off an explosion, killing around 600-1200 people, at least 60 confirmed to be children. Of the super-human individuals involved in the incident only Robbie Baldwin and Nitro survived. Speedball was rocketed from the incident, hanging on to life, and Nitro jumped into the back of a passing pickup truck and fled the scene. This horrific event rushes the Super-human Registration Act, and within a week it gets passed. Although it is not necessary for a superhuman to give away his secret identity to the public, he or she is required to register with SHIELD, giving away all personal information. In return, SHIELD will provide some sort of safe-haven, pay heroes a salary, and they will be scheduled holiday breaks. This is seem as a slap in the face to a large portion of heroes, being forced to choose between become a federal employee, or stop fighting crime. Others, such as Iron Man, see this just as an evolution of Super-humans' roles in society. As a sort of reward for his support of the act, Stark gives Spider-Man an new "Iron Spider" suit that will enhance Spider-Man's abilities with technology similar to Stark's own Iron man outfit.
In a move that would shock the world, Spider-Man would demonstrate his support for both Iron-Man and the bill by coming out publicly in support of the Bill as Peter Parker and Spider-Man. In a shocking conclusion to the secret identity that Peter spent his entire adult life protecting he pulls off his mask in a news conference, saying "I'm Peter Parker, and I've been Spider-Man since I was 15 years old. Any Questions?" It is in this instant that Peter's life will change forever. Friends and enemies are hurt and shocked by the deception. Now knowing that his most hated enemy and one of his most faithful employees are one in the same J. Jonah Jameson fires Parker and begins contemplating legal action he can take against Peter for fraud. Also enraged by the perceived betrayal, Doctor Octopus finds Peter in plain clothes outside of the high school Peter teaches at and fights Peter. Other former villains also begin to launch attacks on Peter and those closest to him, causing Peter to realize one of the greatest fears he had of losing his secret identity. In order to protect those he loves Mary Jane and Aunt May are moved into Stark Tower where they can receive 24 hour protection and monitoring.
Behind the scenes, the U.S. government is working on completion to construction of a secret facility that will come to be known as the Negative Zone prison. This Facility 42 is located in the Negative Zone, and will be accessible at first through a portal controlled by Stark, Mr. Fantastic, and S.H.I.E.L.D. The prison was designed by Tony Stark, Reed Richards, and Hank Pym with the intention of housing superpowered individuals that did not comply with the Superhuman Registration Act. Meant for security, there are facilities for neutralizing and restraining individuals with just about any power imaginable.
As many current and former superheroes and villains begin signing up for the registration act an underground resistance movement begins to grow. Other superheroes begin to band together with Captain America against the act including Luke Cage, Iron Fist, Goliath, Cloak, Dagger, the Young Avengers and many others. The growing friction escalates until the first major battle between Iron Man's registration act support and Cap's "Secret Avengers". This battle involves all of the heroes associated with either side of the conflict, and comes to a climax with the unveiling of a cyborg clone of Thor (presumed to be the actual Norse god at the time) as being in support of the Registration Act. The appearance of Thor surprises both sides of the conflict, as few knew of his existence before this point. The clone is much more violent than the real Thor and kills Bill Foster with a lightning blast through the chest. Horrified at what has happened, Invisible Woman creates a force field around the battered remainder of the resistance allowing Cloak to teleport the team to safety. After the battle Thor is revealed to be a clone rather than the original that was created by Iron Man and Reed Richards and that his violent behavior was an unintentional glitch in their work. This event move begins shaking the resolve of some pro-registration heroes such as Spider-Man and the Invisible Woman and causing anti-registration heroes Nighthawk and Stature to switch sides.
After the death of Bill Foster, the Civil War now spills into the personal lives of Susan Storm and Reed Richards and threatens their marriage by disagreement over the course of action which Reed and Tony have carelessly embarked upon. Offended and hurt when Reed says that he is doing what he is to protect Sue, she erects a cylindrical forcefield that comes crashing through the center of all 35 floors of the Baxter Building and asks Reed if she looks like she needs protection. Unable to come to an agreement, Susan and Human Torch leave the Baxter building under the cover of night to join Captain America's underground resistance to the act. The Thing also finds himself increasingly torn by the direction of the Civil War. He is watching those he loves and respects fight and take sides against each other. On one hand he is against the Superhuman Registration Act because he does not believe in what it stands for. On the other hand he believes himself to be a patriot, and as such does not believe that it is proper for him to be fighting his own government.
At this point the Thunderbolts have already began a recruitment drive, attacking and capturing other former villains for the government to train and employ as a means to capture more of the renegade super-heroes and super-villians. The Super-Human Restraint Unit, a sub-division of SHIELD also starts to neutralize mutants who still display their powers (e.g., stop crime) without registering with SHIELD. Individuals such as Prodigy even get taken down by Iron Man himself.
While transporting captured heroes to the containment facility Spider-Man finds himself uneasy when Iron Man asks him to remain at the head of the caravan of vehicles because of his ability to sense danger. Since he has never disclosed his Spider-Sense to Stark, Stark may have found out about his ability by using the suit to monitor him. A battle erupts when the Secret Avengers meet the caravan to release the captured members of the resistance. Using info from the Yancy Street Gang the anti-registration group tries to free captured heroes. Going after Captain America himself, Spider-Man finds himself in a fight he may not win. The two eventually stop fighting because Spider-Man cannot bring Captain America in himself even if he does win. Meanwhile, the Thing has been unintentionally drawn into the battle despite the Things insistence on remaining neutral. Both sides of the conflict mistake his intervention as acting on their behalf. After the battle the Thing angrily states that he cannot take any more of the fighting, and will be leaving for France. The government puts a hold on all of his finances and closely monitors him. Despite the unwanted attention, Ben Grim makes his way to France away from the conflict.
Possibly because he trusted Peter more (or possibly to watch him turn) Tony Stark takes Peter Parker on a tour of the Negative Zone prison so that Peter can finally see more of the inner workings of the act. Peter's faith in the act had been shaky ever since first agreeing to assist Tony, however it is finally broken as he sees the inhuman conditions in which former allies and enemies are to be kept in the negative zone for their civil disobedience. Occupants are locked up in their cells, and many will never leave because of the escape threat they pose. Some are fully restrained to the point they cannot move their bodies at all and others yet are put in virtual reality goggles to immerse them in a fake world to pacify them. Before leaving Tony leaves Peter alone with Reed briefly. Unbeknownst to Peter, Tony is monitoring their entire conversation (presumably using the bugs designed into Peters suit) where Peter questions a nearly broken Reed Richards about what they have found themselves in. When he gets back to Stark Tower Peter rushes Aunt May and Mary Jane to grab what they can and flee Tony Stark's grasp. Tony crashes in through the wall of the building and begins a fight with Peter that would flow into the streets of New York. Tony incapacitates Peter with a fail-safe he built into Peter's suit. Peter is able to gain the upper hand by reversing the fail-safe (Peter being quite adept with computer technology had already secretly discovered the secret code in his new suit and hack Tony's programming). Peter flees into the sewer and Stark unleashes several of Spider-Man's enemies in the Thunderbolts into the sewers to capture Peter.
Captured and beaten nearly to death, Peter is saved in the nick of time by the Punisher who shoots and kills his attackers. Carrying Peter over his shoulder, the Punisher breaks into Captain Americas secret hideout to get Peter medical attention. The Punisher did not have much patience for costumed superheroes before the Civil War, and probably would not have become involved had it not been for Stark's alliance with the Thunderbolts allowing costumed villains to become government sponsored bounty hunters. Captain America disagrees with Castle's involvement because of his track record, yet tentatively allows him to remain with the group. His tenure with the Secret Avengers is cut short when a pair of costumed villains come to the Secret Avengers hideout with offer of truce to join the cause. Castle automatically shoots and kills them in cold blood causing Captain America to give the Punisher a severe beating. Castle would not fight back due to his respect for Captain America (who as it turns out also played a role in training Castle's army regiment), and simply takes the attack.
Knowing that one of the members of the resistance is actually a double agent for Stark (specifically it is Tigra that is double crossing them), Captain America plans the most massive assault yet on the Registration Act. The plan is to infiltrate the Negative Zone prison and catch Stark off guard. What Tony does not know is that the morning of the attack Captain America sends Hulkling in disguised as Hank Pym to incapacitate Pym and take his place. As one of the key members of Stark's group, Pym has full access to everything about the Negative Zone Prison. Teddy, disguised as Pym, infiltrates the Prison and releases all of the anti-registration heroes and villains that had been captured until this point. Tony along with the registered heroes attempts to head off the Secret Avengers only to discover that the fixed fight that he had prepared in order to put an end to the resistance was now evenly matched. Attempting to stop the fight from leaving the prison, prison officials attempt to close down the portals to the Positive Zone, stranding everyone in the Negative Zone until things are resolved and the Secret Avengers are captured. Not allowing this to happen, Cloak uses everything he has to teleports all of the heroes and villains involved in the conflict through the portal into the middle of the skies of New York.
Raining down from the skies, flying heroes are instructed to assist non-fliers to the ground regardless of their affiliation. Once mobile, both groups begin fighting again, and inadvertently begin destroying everything around them. At the climax of the battle Iron Man has Captain America in his sights, and is ready to take him out of the battle. As instructed by Captain America, the Young Avengers's Vision phases into Iron Man's armor and partially solidifies to take his weapons out of the equation. Caught off guard and with his heavy armor effectively useless, Captain America is able to gain the upper hand against Iron Man. Pummeling him with his fists and his shield, Captain America raises his shield over the smashed helmet of Iron Man. Looking through the pieces of his broken armor up at Captain America he simply challenges "Do it." Before Captain America is able to bring his shield down upon Tony's face he is tackled by nearby government workers: police, firemen, and other emergency personnel. At first struggling against them, Steve Rogers stops and drops down. The battle around him begins to stop almost immediately. Rogers is horrified by the realization that he was no longer fighting for the people that he was sworn to protect. Looking at the carnage around him and seeing for the first time the true cost to everyone involved (civilian and super power alike), Captain America surrenders and tells his team to stand down. For better or for worse, Steve Rogers has single handedly ended the Civil War. While some heroes including Captain America are taken into custody following the final battle of the War, many escape including some key members of the Secret Avengers.
While sides were changed during the war, this is a tally of the main characters and teams involved on either side of the Civil War at the end and the official stance they took on registration.
Iron Man, Hank Pym, Mr. Fantastic, She-Hulk, Ms. Marvel, Sentry, Wonder Man, Tigra, Stature, Bishop, Doc Samson, Black Widow, Thor clone, Wasp, Henry Gyrich, Val Cooper, Tigra ,Venom
Avengers, Great Lakes Initiative
Captain America, Spider-Man, Invisible Woman, Goliath, Iron Fist, Hercules, Black Panther, Storm, Spider-Woman, Human Torch, Luke Cage, Cloak, Dagger, Hulkling, Arachne, Punisher, Falcon, Typeface, Vision, Madrox, Cable, Nick Fury, Jessica Jones, Namor, Patriot, Bucky Barnes, Kate Bishop
Secret Avengers, X-Factor
The Thing, Doctor Strange, Firestar, Deadpool
A list of those that died during the course of the Civil War. While the total number of deaths during the War were small, some major characters in the Marvel Universe rocking the course of Marvel continuity.
Deceased during the war: Captain America, Goliath, Thor clone, Typeface, Bantam, Jack O'Lantern,Jester
Stanford Incident: Night Thrasher, Namorita, Microbe, Coldheart, Cobalt Man, and Speedfreek
In the United States, a Super-human Registration Act is passed, which decrees that all Mutants or Super-Humans must register with the government, giving all personal information, as well as powers. Registration is required of all Mutants and other Super -Powered individuals. Anyone without powers that wishes to don a costume to fight crime is also required to register. Individuals that accept and register will effectively become government S.H.I.E.L.D.. Agents and will be trained by S.H.I.E.L.D. and are required to work for the government on government salary. Amnesty for past actions is also offered as an incentive to registrants. Parallels can be drawn between the Super-human Registration act and the Mutant Registration Act.