yes "War"
It's never used on my server because the Towny dev half assed implementation leaves a lot to be desired.
Still there is hope, I had noticed not so long back another developer who had the right idea and was working on plugin for towny, a way of allowing individuals towns to goto war (much better), this takes things out of the Nation context and server "War" for all towns/nations, forcing town owners to goto war just because the of the Nation they are in (which just opens things up to retarded greifers. Nations which is another stupid thing from Towny that really serves little useful purpose in its current state as it doesn't provide enough finite control on town/player permissions. Right now its only purpose is giving players a way to get a green chat name