#41, Battle of Antietam: America's Bloodiest Single Day
Antietam on September 17, 1862, produced 22,717 casualties in 12 hours, approximately 3,650 dead and 19,000 wounded or missing, making it the single bloodiest day in American military history. George McClellan's 75,000-strong Army of the Potomac attacked Robert E. Lee's 38,000 Confederates along Antietam Creek near Sharpsburg, Maryland, in three uncoordinated assaults that squandered Union numerical superiority.
The Cornfield changed hands 15 times in four hours, with entire regiments advancing into point-blank musket fire and being annihilated. The Sunken Road, afterward called "Bloody Lane", was filled with Confederate dead stacked two and three deep after Union troops finally flanked the position. Burnside's Bridge, which 500 Georgians defended for three hours against 12,000 Federal troops, became a symbol of tactical incompetence meeting stubborn courage. Though tactically inconclusive, Antietam was a strategic Union victory that gave Lincoln the political cover to issue the Emancipation Proclamation, transforming the Civil War from a fight to preserve the Union into a crusade to end slavery, and ensuring that Britain and France would never recognize the Confederacy.
