This 1862 photo made available by the Library of Congress shows dead Confederate soldiers in a ditch on the after the Battle of Antietam near Sharpsburg, Md. When dawn broke along Antietam Creek on Sept. 17, 1862, cannon volleys launched a Civil War battle that would leave 23,000 casualties on the single bloodiest day in U.S. history and mark a crucial pivot point in the war. And yet it might never have occurred - if not for what a historian calls a "freakish" twist of fate. Days earlier, a copy of Gen. Robert E. Lee's detailed invasion orders, wrapped around a few cigars, accidentally fell in a farm field and were discovered by Union infantrymen who passed their stunning find up the chain of command, spurring action. (AP Photo/Library of Congress, Alexander Gardner)
