I've actualy maniged to loose the battle, just once but it was a clear loss, I though ALL my forces on the enemy lines and in the end all my soldiers were, dead, woulded or ran away I had nobody left, the enemy had held with no problems they only lost a few % of what I did.
But yes, with out the Full ai you don't realy know just how good the ai is, but even so, I have had a few close calls