How do you beat Plains of Rohan in Lord of the Rings the game

You first kill all the nubered orks then go up the hill and when the elphants close shoot the crossbow missle and keep hiting it till it dies. Then when its on the other side keep doing the same thing until you face the nazgul and ring wrath use legolas and shoot it with arrows until it dies but try to kill the orks that are charging at you while your firing at the nazgul then the dead will finish it for you then your done that's it