As an English or math teacher for the past 19 years, I weigh heavily on the "not as important" side. However, there isn't ANY topic that I teach that isn't more interesting for students. They read the historical accounts of past US wars like they are fiction. They get "into" the characters.
It's a win-win if you can incorporate history topics into the other subjects.
Do I think it's relevant to recite the Preamble? No.
Do I think it's necessary to know every date? No.
Do I think SOME history teachers kill the content? Yep.
I think it's important to tell the stories, good and bad.