Thursday, September 4, 1862
As the advanced unit of the Confederate Army, Confederate General Daniel Harvey Hill crossed the Potomac River near Leesburg. General Robert E. Lee, buoyed by his successes during the Seven Days Battles and Second Manassas, led his army into Maryland, hoping to attract recruits from this border state and to gather food and supplies for his army. Lee wished to remain on the offensive, maintaining an aggressive campaign to relieve pressures on Richmond.1
1George A. Bruce, The Twentieth Regiment of Massachusetts Volunteer Infantry 1861 - 1865 (Cambridge, Massachusetts: The Riverside Press, 1906), 147-8.