I love those defensive hill battles, especially with gunpowder, since that´s one situation in which gunpowder units are of real use (bridge battles are the other), the height advantage gives the the necessary reach and their morale penalty sends the enemy to run. The good thing is, they´ll retreat, rally, charge again, lose a couple of men, rout, rally... an ideal situation if your goal isn´t to rout the enemy but to decimate his army.