Got a pop up that stated the wildlings had taken the wall and all the surrounding lands, so I go up there looking for a fight, but they actually didn't take a thing. The North declares war on them, but that's about the only thing that actually took place.
Are you sure they didn't take the wall then lost it again? I cant remember the stipulations for this so I will check it. It might be best if I make it fire when several Nights Watch locations are taken from the Wildlings.
This also happened to me just now. Got a letter that they breached the wall but they didn't take anything. In my recent notes log the last thing related to this is The Shadow Tower is no longer under siege.