Umm you sure about the agressing of that triggered the second war? Don't remember that, only remember TC whipping new members from Rana during th first war. As for Borg peacefulness I think would go into a Borg history.
The TC's aggression toward neutral states is one of the things that caused our rivalry and even our cold relations. I don't think it provoked war, but it certainly didn't make relations any warmer.