Avengers :Season 1, Episode 17: "Come the Conqueror"

"Come the Conqueror" - Kang’s invasion of Earth begins in earnest! A fleet of ships from the future unleash war on the planet, and the Avengers are helpless to stop it. But while Iron Man searches for Kang himself, Captain America takes charge of the Avengers…but to fight a war, you need an army. And Wasp knows where Cap can get one. Welcome to the other dimensional prison called 42, maintained by a robot called Ultron.