Saturday, September 13, 1862
Union General George McClellan came into possession of Confederate General Robert E. Lee's Special Order Number 191 to his subordinate officers, dated September 9, which revealed the movements of the Confederate Army in Maryland and Virginia. McClellan now had the means to crush the Confederate Army, but, as in the Peninsula Campaign, he delayed in taking action for eighteen critical hours.1
1George A. Bruce, The Twentieth Regiment of Massachusetts Volunteer Infantry 1861 - 1865 (Cambridge, Massachusetts: The Riverside Press, 1906), 153-4. Richard F. Miller, Harvard's Civil War: A History of the Twentieth Massachusetts Volunteer Infantry (Lebanon, New Hampshire: University Press of New England, 2005), 164.