This story introduces Hate Monger.

A purple-hooded xenophobe comes to New York and starts causing race riots.  Ben Grimm has no tolerance for bigots.

But Sue, apparently, gives off a “not in my backyard” philosophy.

Hate Monger uses his abilities to increase hatred to get the FF to fight each other, with Mr. Fantastic identifying Thing’s weakness…

…and then all storm off, breaking up the FF (again).

But a new hero arrives to help…

Nick Fury. No eyepatch.

This is the first time Stan Lee tried to tie Marvel’s “period comics” (i.e., World War II comics) into the main Marvel Universe.  Fury is no longer a Sargent, he’s a Colonel.  And he’s after Hate Monger.  The team re-forms and they take him down.

Hate Monger, dies at the end and we see him unmasked as Hitler.

Later, when Marvel writers realized that the ending “twist” here was heavy-handed and very 1960s–and more than a bit stupid–it will be retconned, so that this is a clone of Hitler created by Arnim Zola.

Reed does acknowledge, though, that Hitler was rumored to have many “doubles” (and this has an historical basis).