In ETW and NTW, there was no option to allow another army of the player's faction to fight alongside the player's army in the field. This is extremely unrealistic. I am no psychology expert, but if there was a general that is reinforcing you, I would tell that general to fight too. Not just wait and replace the army limit as the units start to route or die. Was there this option? If so, I could not find it. I know it was in Rome Total war and Medieval 2.
Does anyone know if this is implemented into Total War : Shogun 2?