Eric is spot on in his analysis of Civil War online discussion groups.
"Every group seems to have a real “know-it-all”."...and so many names come to mind when Eric relates the common characteristics of the self-appointed group overlord whose "standard response is to adopt an extremely insulting and condescending tone that stops just short of being a flagrant personal attack, dress it up in a veil of trumped-up courtesy, and then wait for the recipient to be offended. It’s obviously a calculated thing, because it happens all the time. Then, when the poor unenlightened fool responds angrily, he takes on the role of the martyr with a hurt tone. To make things worse, X’s got a group of sycofants who will defend him, even if he is being rude and insulting."
One set of boards where this phenomenon is noticeably absent are the Civil War Message Boards created and moderated by Jim Martin. Organized by specialized subject (artillery for instance) or by state, professional historians, authors, and multitudes of informed researchers and enthusiasts frequent them and contribute to the discussions, often sharing their research. I only follow a few of the boards regularly, but the ones I frequent the most (AR, MO, KY, and LA) are well-moderated.