In the comics, the first Annihilation War basically broke the galaxy. All of the different space empires were in shambles, and the techno organic alien race known as the Phalanx took the opportunity to try and take over the universe. They never would have been able to do it, either, if it wasn't for Star-Lord. He had invited a group of Space Knights (think of them as interstellar super-cops) to come update the Kree homeworld's security systems. It turns out, however, these Space Knights had already been infected and consumed by the Phalanx, who had actually been taken over by Ultron. One thing leads to another, and the entire universe is almost assimilated into the Phalanx consciousness—all because Star-Lord thought the Space Knights were cool. No, they're not cool. They're a dumb relic of the 1980s and everyone else has moved on, Star-Lord. Sure, he helped fight them off, but starting an intergalactic war isn't the sort of thing you can just apologize for and move on.