Responding to tragedy: The Guardian looks back at Marvel Comics' response to 9/11: Heroes and A Moment of Silence:

"Among the Marvel characters who make an appearance in Heroes, there are two who figure more prominently than the rest, both for a good reason. Captain America had been invented as Marvel's superweapon against Nazi Germany in 1941, leading the way a whole year before the US finally went to war. The Hulk, meanwhile, would unfold his devastating superhuman powers only if he was 'made angry'. Together, these two seemed a good choice for driving home the notion of yet another historic cause, stressing the connection between anger and justified violence without having to depict anything more than a well-known and well-respected protagonist."