One thing I learned the hard way, is never let the AI control your re-enforcement....in RTR the Gauls were besieging that one settlement with a B next to arretium(I forget the name) where Maesa Haemus was..a two star General, 21 years of age and son of Decimus Haemus whom was a five star general. Well in the battle where Decimus is attempting to keep his son from certain death, bum rushes the Gauls with his Merc army, destroyed and killed. He did enough damage to allow Maesa(me) to rout the seiging army...

I dont know how far off that is, but when it comes to battles, never trust the AI with your warriors.(I've been playing RTW for a year or so now, I avidly visited these forums but now im seeking to be more active in the community)