Up until now, Marvel Studios has mostly avoided basing their movies on specific storylines. Captain America: The Winter Soldier was actually the first to be named after one, but both that and this year’s Avengers: Age Of Ultron very much told their own stories from their print namesakes.
Civil War however is a very different animal. One of the most successful Marvel events of all-time, the comic book changed how these types of stories are handled, making them a yearly fixture which encompass pretty much every title on the stands. The wildly popular storyline is one fans have been dreaming of seeing ever since Captain America and Iron Man first met in The Avengers, but the downside to a story with so many iconic moments is of course the fact that not all of them are going to make it into the movie.