Before Meryvn came over for our Conquest of Paradise game Nevin and I played the Rohan Battle scenario from War of the Ring: Battles of the Third Age. Nevin took command of Saruman's forces and I took Rohan. The game went to position 12 or 13 of the Fate Track when Saruman cried uncle after his forces attempting to take Helm's Deep were decimated by the Ents storming out of Derndingle (Fangorn) and then regrouping in the Deeping Coomb forming a defensive barrier to future Shadow attacks. Before the Ent attack the Shadow forces were making good progress first eliminating Eomer and his forces on their way to Helm's Deep and overrunning the forces in the Fords of Isen and the East Fords. Theoden appeared in Edoras and Aragorn in the East Entwade both prepared to march to relieve the siege of Helm's Deep before the Ents appeared.
Posts on Boardgamegeek say that the Rohan player has little chance if the Saruman player chooses the third position exclusively, The Pits, on Shadow Box after the first few turns. I'd like to play this one again to test this out.