Two armies attacking the same province

[Forrest]

You missed my favoritest reason of all. In nations with stealth a third of your army will not fight because it moved in stealth mode by error. Of course it is the H Inf.

Here is a good one. You just captured a castle so when you move in a defending army it does not defend but hides inside while your 8 mages take on the enemy to their deaths.

Of course when you are giving move orders to 20 commanders you will miss someone in the confusion. Usualy longbow or H Inf.

No it does not always work even when it should.