Waterloo (BBB).
This was the scenario we put on at the Oxfordshire military museum last year. I ran it twice on successive days with different teams of players. First game: Allied dice on the right wing were absolutely dire throughout. The French were able to seize La Haye Sainte and Hougoumont, repel counterattacks and smash Allied units with massed artillery, and comfortably fend off the Prussians. A clear French win. Second game: a different story. More aggressive (and less unlucky) Allies contested everywhere vigorously. Hougoumont changed hands twice, La Haye Sainte three times, and the Prussians drew large French forces off to protect Plancenoit and their line of communications. The French were fortunate to escape with a draw.