American Battlefield Trust’s map of the Battle of Antietam
At dawn on September 17, Maj. Gen. Joseph Hooker’s I Corps mounted a powerful assault on Lee’s left flank from the Joseph Poffenberger farm near the North Woods. Repeated Union attacks and equally vicious Confederate counterattacks swept back and forth across farmer David Miller’s cornfield. Maj. Gen. Joseph Mansfield’s XII Corps supported Hooker’s left, attacking Jackson’s Confederates from the East Woods, Mansfield was killed near the Smoketown Road. Rebel dead lined the fences along the Hagerstown Pike as the Union infantry pushed south through the corn. Brig. Gen. John Gibbon’s Iron Brigade and Brig. Gen. George Meade’sPennsylvania Reserves fought particularly hard on the Union right and center.