Miraculously, the outlook for the wounded changed just two weeks later. On September 17, 1862, Union and Confederate forces clashed again at Sharpsburg, Maryland, in the Battle of Antietam. After 12 hours of fighting, some 23,000 men (over 12,000 Union soldiers and more than 10,000 Confederates) had fallen-the bloodiest single day of combat in American history. In stark contrast to the delays experienced at Manassas, every injured Union soldier was evacuated from the Antietam battlefield within 24 hours.
The author of this dramatic turnaround was a lanky, bearded, Donald Sutherland look-alike-Maj.