Despite their status as Earth's Mightiest Heroes, even the Avengers suffered the bitter sting of defeat in their early years. With members as different as Iron Man and The Hulk, it's no wonder they sometimes failed to work as a coordinated team. This was a weakness that strategic villains like Kang and Loki learned to exploit in the superheroes' fledgling days.
Source：https://www.cbr.com/avengers-first-losses-marvel-comics/
