However, the overuse of that trope elsewhere should not blind us to the fact that there are, sometimes, national catastrophes that genuinely are of historic proportions. The Iraq War will haunt U.S. foreign policy for a generation, as Vietnam did, though perhaps less severely. Or perhaps more severely: Vietnam did not become a breeding ground for terrorist organizations and deludedly utopian religious fundamentalists (unless you count the Vietnamese communist government, I suppose, but as theirs was not a religious conviction, it has mellowed over time).

Anyway, I don’t mind the trope as much as you do, I have to admit. Much good writing contains set pieces; I think they’re actually necessary in some ways, to give the reader’s brain time to catch up with the more original phrases.

It wasn’t entirely clear to me whether you were objecting to the trope no matter what the value of X, or just to the use of “historic”.

Ooh, I finally got to use the word “trope”.