Quote Originally Posted by Adrian II
There is a downside to this: when your province has 960+ troops in unit by unit stacks and the province is attacked, the AI wil group those units into an army for you and it will stack them in order of their entry into the province.

Beware of this effect, or you may end up on the battlefield with a totally clumsy army composed of, for instance, 14 Spearmen units, one unit of 3 Royal Knights (whose commander is a 'Coward') and one unit of 11 Elite Crossbowmen...
I don't think I've ever had this problem. When you go to the pre-battle screen you can pull whatever units you want out of the reinforcements pool and put them on as your starting army. If you have the Viking Invasion add on you can even arrange your reinforcements to come on in whatever order you wish.