[Barnacle Bill]

In the latest Starfire rules, they have rules for the "AI" that create several levels of war. This basically determines how many systems the "AI" tries to grab before looking for a peace treaty. Other rules cover how much they will lose before looking for a peace treaty, and takes into account other wars, etc...

BTW, the American Civil War was not one "that wasn't going to end until one side or the other was utterly defeated". The North was fighting to utterly defeat the South, but the South was just fighting to get the North to go away. The North could have had peace at any time, just for the asking, by granting Southern indepenence. Had the South utterly destroyed the Union army, they had no intension or desire to annex the North to the CSA, just to gain independence from the USA.