Immediate after his stunning victory at Second Bull Run, Lee decided to thrust into Maryland. Lee crossed the Potomac
River into Maryland on September 4, 1862.
General McCellan moved the Union Army westward to intercept the Confederates.
On September 10, 1862 Lee orders a four-way split of his army.
Stonewall Jackson, John Walker and Lafayette McLaws are sent to Harpers Ferry to open a Confederate supply line through the
Shenandoah Valley, and James Longstreet and D.H. Hill are to head north to threaten Southern Pennsylvania.
General McClellan (Union) started his army
advancing toward Frederick, Maryland on a front 25 miles wide. On September 11, General McClellan's advance guard approached
Frederick, Maryland. General McClellan is pushing his army westward hoping to catch General Lee
On September 14, after an opening clash at Stone Mountain, Lee's army falls back
toward Sharpsburg to await the oncoming Union army. Lee makes his Headquarters in the area of Dunker Church.
On September 14, McCellan arrived at Stone Mountain. The Union army
drove the Confederates from the pass breaking thru at Stone Mountain. However, Stonewall Jackson had triumphed at Harpers
Ferry, maintaining an open path for Lee's supply line. That same day Lee orders all Confederate units to concentrate
at the town of Sharpsburg.
By first light on September
17, most of Lee's army was ranged on a ridge north and ease of Sharpsburg.
Union General Hooker's I Corps launched their attack at 5:30 a.m.. There in a cornfield the armies clashed back
and forth until 7:00 a.m., when the bloodletting finally forced a stalemate.
At 7:30 a.m., Joseph Mansfield's XII Corps advances pushing the Confederates from
the cornfield. The Union Army continues it's advance, but when reaching the high ground around the Dunker
Church it was low on ammunition and around 9:00 a.m., the fighting subsides and a lull settled over the battlefield.
About 9:15 a.m., the Union's II Corps fords Antietam Creek and Plunges into the
fighting. The confederates were waiting for them and in within minutes almost half of the attacking Union troops were
killed. But, more Union troops crossed Antietam Creek and by 12:00 the Union Army had cracked the Confederate center.
Meantime Union General Burnside had been ordered to cross Antietam Creek to the south at the Lower Bridge, soon
to be called the Burnside Bridge.