The bloodiest single day in American history, it gave Lincoln the political basis to issue the Emancipation Proclamation and halted Confederate expansion into Union territory.
Key Facts
- Date
- September 17, 1862
- Total casualties
- 22,726 dead, wounded, or missing
- Confederate force ratio
- Outnumbered approximately two-to-one
- Union forces engaged
- Less than three-quarters of McClellan's army
- Political outcome
- Enabled issuance of Emancipation Proclamation
- Theater
- Eastern Theater, first on Union soil at field army level
Location
Cause → Event → Consequence
Confederate General Robert E. Lee launched the Maryland Campaign, crossing into Union territory with his Army of Northern Virginia. Union Major General George B. McClellan pursued Lee, intercepting his forces near Sharpsburg, Maryland, along Antietam Creek, setting the stage for a confrontation between the two armies.
On September 17, 1862, Union forces launched a series of attacks against Lee's defensive positions. Fighting raged across Miller's Cornfield, the Dunker Church, and the Sunken Road, temporarily piercing the Confederate center. A late Confederate counterattack by A. P. Hill's division from Harpers Ferry repulsed Burnside's corps, ending the battle in a tactical standoff, though Lee withdrew his battered army south of the Potomac.
McClellan's repulsion of Lee's invasion was declared a strategic Union victory. Lincoln, bolstered by the result, issued the Emancipation Proclamation, which discouraged British and French recognition of the Confederacy. McClellan was relieved of command in November for failing to pursue Lee aggressively, and the battle marked a decisive shift in the war's political and diplomatic momentum.
Belligerents & Mobilization Analysis
Side A
1 belligerent
George B. McClellan, Joseph Hooker, Ambrose Burnside.
Side B
1 belligerent
Robert E. Lee, A. P. Hill.