I have played TI3 many times. But now my gaming group had enough of it for a while. The thing is that you spend most of your time building up an empire (even with simulated early turns), then get into a war and al is won or lost with a major battle, in which both sides spend all their extreme action cards. Then one side will have won that battle and their is no reason whatsoever to stop the war and let your victim live. Except if others attack you in the back.
We also play a lot of Napoleon in Europe (Eagle Games) and there you always have the opportunity to sue for peace. Sure, you’ll lose a couple of provinces, but you may not get DoW-ed by the aggressor for a year and your army is intact.