The latest post from Michael Akinde on the combat model of Imperium deals with how battles actually transpire. The best part:

Perhaps the most common situation when two sides meet is that one of them withdraws from battle. In this period, it was almost impossible to force a battle on a reluctant enemy, and the same will be the case in Imperium. Withdrawal comes with a price, though; whenever a General withdraws from battle, it will affect the “imperial morale” of the empire and the prestige of the General. The price will depend on the size of the forces and the relative strengths of the armies involved. The people are obviously not going to be as concerned when a force of 4000 men refuse to fight with 40,000 men, as they would if the opposite was the case. This is one more mechanism which I expect will make skilled enemy commanders like Hannibal a nasty proposition in the game. Imagine the 20+ Roman units that you have finally collected down in Apulia suddenly running into Hannibal with his 16 or so units. You might not fancy your chances too much, knowing that a large proportion of your troops are still recruits, that Hannibal is the best Commander of the period and leads a veteran army… nevertheless, you will have to make a choice: do you run away, further depleting Roman morale and the prestige of your General? Or do you face down the Carthaginians on the banks of the Aufidius?

So, Michael, what are the chance of this being done by the end of 2009?