At the Battle of Cedar Creek, in October of 1864, Jubal Early very nearly pulled off a surprise victory against Phil Sheridan's larger army in the northern Shenandoah Valley. With any number of PODs, a decisive Confederate victory could have been achieved.
Suppose that the battle turned into a Confederate victory on the level with Second Manassas, with Sheridan's broken army fleeing northwards towards Harper's Ferry and leaving the Confederates in possession of the battlefield. Would this has had any serious repercussions? It might be too late to influence the presidential election, and the agricultural productivity of the Shenandoah Valley had already mostly gone up in smoke thanks to Sheridan's scorched earth tactics. Would a Southern victory have been essentially meaningless, or could it have had a significant impact?