hmmm this brings up all kinds of really good points and suggestions.
If battle length was determined by the odds of the troops, we get a much more interesting combat calculator.
I'd suggest if implimented the combat length calculator be based on 2 things. Max # of troops, and ratio of troops.
With the right number of troops, someone could create a battle against a much larger enemy and have their allies join the battle midway through to shift the battle in their favor. This seems like a great concept to advance military tactics without altering the current combat mechanics.
The full potential would be that the first army to attack an encampment/city would not have to suffer 100% casualties every time. They first army to attack would begin combat, and they would begin loosing troops much faster than the defenders. While combat is still going on additional troops could join forces.
This seems to heavily favor attackers instead of defenders, so defensive reinforcements midbattle would have to receive additional buffs to compensate. But I think it could be a fun addition to the game.
Max time for battle resolution would have to be like 2 hours or something. to prevent these things from lasting forever.