In Fantasy Warmaster I've won a game with a single round of fire from a pair of cannons at a unit that the opposing general had joined by wiping it out with driveback... A big block of zombies, which I bounced the general into the centre of, then proceeded to engage all of the other seven or so units in combat, so that my nearby cannon brigade on a hill could only target the unit containing the general, as units in combat are not eligible as targets for shooting, and combined with the firing overhead rule, I took out his Vampire General with cannon balls...
Of course even if the shooting hadn't taken him out the combat round would have. Since it was actually part of a tournie, I shouldn't have done any shooting, or just shot with one of the units to take a stand out and cause some confusion. As I would have received far more VP's from taking all of those units out...