Although it is little remembered now, for at least a few hours, the Battle of South Mountain, September 14, 1862, was almost one of the most memorable of the Civil War. As historian Scott Hartwig put it, “thanks to Jacob Cox’s early initiative and aggressive generalship, McClellan had nearly won Fox’s Gap and Turner’s Gap cheaply and early in the day.”
That is, Cox and his men of the Kanawha division (including future presidents Rutherford B. Hayes and William McKinley) almost pushed the Confederates off South Mountain — and would have with better support (which arrived too late). As it was, the Union victory that day caused Robert E. Lee to decide to return to Virginia, ceasing his movement to the North at least for a time. Ultimately he reversed that decision and the Battle of Antietam three days later was one result.