Well that must not have been enforced very well because I've been going to FW since I was a kid (so say for the last 30 years or so), and I can remember having fires at ours (and seeing others campfires) for pretty much as long as I can remember.
And I personally would take the word of someone that works at Ft. Wilderness over anyone else, but I guess we differ there. Unless a ranger asks me to put it out, if they tell me I can have one, I'm going to have one.
I'm not saying that there wasn't a fire ban back in the day, but in my 30 years of having fires in Ft. Wilderness (minus when they had, as you mentioned, signs up banning them) I have never once been told to put one out. Maybe it's just enforced more now a days, not sure, but if they tell us we can have a fire when we check in, it's marshmallow time
P.S. Considering both Ft. Wilderness said they were now allowed, and the recent poster saying they saw campfires all of last weekend, it appears the ban has been lifted. Could it return next week? Of course, but as of right now, it appears to be lifted. And that is fine and dandy with me, just keep it lifted for a few more weeks please
