Ancient warfare was all about the pitched battle last time I checked. When you initiated contact there wasn't much more you could. There were skirmishes before all of this but they were not that important. The whole maneuvers were as to where you'd confront the enemy, on what terrain, and in what formation, etc. Armies could spend days watching each others before the commanders decided to fight or not. There could be some surprise attacks such as Caesar's jumping on the gaul lines. I'm not sure about the warfare in EU's timeframe and if it is well represented at all in the game, but the system should be different, at any rate. You can't engage a mass of men in melee and then just pull back, they'd all just get cut down as they try to escape, it makes sense.