In Civil War, Captain America and Iron Man clashed in an ideological conflict that tore the superhuman community apart. Steve and Tony went to the mat for their conflicting conceptions of liberty vs responsibility, leading to Captain America's tragic assassination and Iron Man's elevation to the head of S.H.I.E.L.D. But events didn't have to go that way, and Tony Stark actually got a glimpse at another path in which he was the fallen hero, and Steve Rogers was the armored Avenger.
In What If? Civil War #1's 'What If Captain America Led All the Heroes Against Registration?' (from Kevin Grevioux, Gustavo Duarte, Sandu Florea, Victor Olazaba, Scott Koblish, Gustavo Duarte, and Joe Caramagna), Uatu the Watcher shows Iron Man what would have happened if, before the events of Civil War, Tony Stark had been killed during the events of Iron Man: Extremis. After the Avengers mourn Tony and defeat the supervillain Mallen, the Stamford Tragedy once again claims countless innocent lives, turning public sentiment against superheroes. But this time, without Tony to act as an alternative figurehead, Marvel's superheroes put aside their reservations and unite behind Captain America and his anti-registration mission.
Related: Fantastic Four's Alternate Civil War Ending Was a Stark/Rogers Romance
Sadly, without Tony to steer the government's response, the human supremacist and former Avengers liaison Henry Gyrich is able to fill the vacuum, redirecting the government's anti-mutant Sentinel program to take down Captain America's forces, killing Spider-Man and the Invisible Woman. After realizing he's losing the battle for public opinion, Captain America decides the heroes need additional inspiration, donning an Iron Man suit Tony gifted
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