With the cinematic Marvel Universe expanding at a seemingly exponential rate, historian Daniel Immerwahr‘s essay in n+1 takes a step back to look at the evolution of superheroes: they used to stick up for the underdog and actively work for justice, and there was a lot of Nazi-punching. Now, they fight villains who look a whole heck of a lot like themselves, and their main function is protection (at least, for the dudely superheroes; Wonder Woman remains an exception). And looking at this shift teaches us a lot about U.S. attitudes toward war and peace.

What these heroes are fighting, in the end, is themselves. And in doing so, they’re channeling a cultural ambivalence regarding the weapons of today’s wars. Iron Man intervening in global affairs is good, but Iron Monger (the villain of the first film) doing so is bad. The world needs SHIELD but fears HYDRA. It’s as if the films can’t put forth a hero to protect society without immediately imagining how he might threaten it.

Often, the lines blur. “Hey Cap, how do we know the good guys from the bad guys?” one of the Avengers asks, as he tries to sort HYDRA from SHIELD. “If they’re shooting at you, they’re bad,” is Captain America’s less-than-conclusive answer. It’s a quick joke but a meaningful one, because it gets at the central, uncomfortable truth about life in the United States that these movies dance around. The good guys—surveilling everyone’s communications, calling down air strikes, fortifying themselves against the world—look an awful lot like bad guys.

Read the essay