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.
