American Battlefield Trust’s map of the Battle of Fox’s & Turner’s Gaps
When Gen. George B. McClellan was given a mislaid copy of Lee’s Special Order 191, the Union army commander knew that portion of Robert E. Lee’s divided army was vulnerable to attack and ordered his troops toward South Mountain. A small Confederate force under D. H. Hill protected Turner’s and Fox’s gaps, two vital passes through the South Mountain range. An early assault by the Union Ninth Corps at Fox’s Gap was initially successful claimed the life of Confederate Gen. Samuel Garland, but lacked sufficient support to drive on to Turner’s Gap to the north. Reinforcements, however, were slow to arrive, giving James Longstreet’s Confederates time to strengthen Hill's position.
At 4 p.m.—seven hours after the fighting began—Union divisions under generals George Meade and John P. Hatch made a relentless charge on the Confederates left flank. At the same time, Jesse L. Reno’s Ninth Corps made an effort to seize Turner’s Gap from the south. A bloody see-saw battle for control of the pass continued until dark.
After nightfall, Lee, Longstreet, and D. H. Hill agreed to abandon South Mountain before daylight on September 15. The bloody, day-long struggle, bought the Confederate army valuable time to consolidate its position—and ready itself for the coming battle along Antietam Creek. McClellan had lost his best chance of destroying Lee’s army in detail.