Battle of Antietam

The Battle of Antietam (/ænˈtiːtəm/ an-TEE-təm), also called the Battle of Sharpsburg, particularly in the Southern United States, took place during the American Civil War on September 17, 1862, between Confederate General Robert E. Lee's Army of Northern Virginia and Union Major General George B. McClellan's Army of the Potomac near Sharpsburg, Maryland, and Antietam Creek. Part of the Maryland Campaign, it was the first field army–level engagement in the Eastern Theater of the American Civil War to take place on Union soil. It remains the bloodiest day in American history, with a tally of 22,727 dead, wounded, or missing on both sides. Although the Union Army suffered heavier casualties than the Confederates, the battle was a major turning point in the Union's favor.

After pursuing Confederate General Robert E. Lee into Maryland, Major General George B. McClellan of the Union Army launched attacks against Lee's army who were in defensive positions behind Antietam Creek. At dawn on September 17, Major General Joseph Hooker's corps mounted a powerful assault on Lee's left flank. Attacks and counterattacks swept across Miller's Cornfield, and fighting swirled around the Dunker Church. Union assaults against the Sunken Road eventually pierced the Confederate center, but the Federal advantage was not followed up. In the afternoon, Union Major General Ambrose Burnside's corps entered the action, capturing a stone bridge over Antietam Creek and advancing against the Confederate right. At a crucial moment, Confederate Major General A. P. Hill's division arrived from Harpers Ferry and launched a surprise counterattack, driving back Burnside and ending the battle. Although outnumbered two-to-one, Lee committed his entire force, while McClellan sent in less than three-quarters of his army, enabling Lee to fight the Federals to a standstill. During the night, both armies consolidated their lines. In spite of crippling casualties, Lee continued to skirmish with McClellan throughout September 18, while removing his battered army south of the Potomac River.

McClellan successfully turned Lee's invasion back, making the battle a strategic Union victory. From a tactical standpoint, the battle was somewhat inconclusive; the Union Army successfully repelled the Confederate invasion but suffered heavier casualties and failed to defeat Lee's army outright. President Abraham Lincoln, unhappy with McClellan's general pattern of overcaution and his failure to pursue the retreating Lee, relieved McClellan of command in November. Nevertheless, the strategic accomplishment was a significant turning point in the war in favor of the Union due in large part to its political ramifications: the battle's result gave Lincoln the political confidence to issue the Emancipation Proclamation. This effectively discouraged the British and French governments from recognizing the Confederacy, as neither power wished to give the appearance of supporting slavery.