Star Wars
From Rumblepedia
There once was a time where almost every thread was a Star Wars thread, spurred on by invasions from outside sites; each of these threads ended in bannings and general hate. The conflict was ended however with the end of the Star Wars Prequals fad and repeated moratoriums.
In the past Star Wars topics had resulted in no less than two 'anti-idiot' invasions from outside sites proclaiming the unfairness of how Star Wars would lose battles at CBR that they felt that they shouldn't. However, due to difference between The Rumbles rules on validatity of secondary source information and the other site's; neither side could really understand the other's position, and no common ground was found.
In the past ages of CBR this continuing battle while a nusicense wasn't a problem, only recently in 2004 and 2005 with release of The Prequals did it ever result in serious conflict.
All in all Star Wars remains a very popular topic dispite the looming threat of invasion from the other site.