# Canonical recap data for Battle of Antietam (1862)
# Source: https://recap.at/1862/battle-antietam
# Format: YAML 1.2 (UTF-8). Generated at request time.
slug: battle-antietam
canonicalUrl: "https://recap.at/1862/battle-antietam"
title: Battle of Antietam
aliases:
- Battle of Sharpsburg
- September 17, 1862
- Antietam Creek
subtitle: The bloodiest single day in American military history (September 17, 1862) halted Lee's invasion of Maryland and became the turning point in the Civil War narrative—a critical gap in our war coverage.
recapType: global_event
eventStatus: concluded
startDate: 1862-09-17
datePrecision: day
year: 1862
decade: 1860
country:
name: United States
slug: united-states
summaryShort: The Battle of Antietam, 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 Sharpsbur
summaryLong: The Battle of Antietam, 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 22,726 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.
lede: On September 17, 1862, Union and Confederate forces clashed near Sharpsburg, Maryland, in the deadliest single day in American military history. Robert E. Lee's invasion of the North was halted, giving Abraham Lincoln the strategic opening he needed to issue the Emancipation Proclamation.
heroImageUrl: "https://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Thure_de_Thulstrup_-_Battle_of_Antietam.jpg/1280px-Thure_de_Thulstrup_-_Battle_of_Antietam.jpg"
heroImageCredit: Wikipedia · "Battle of Antietam"
importance: 85
sourceConfidence: 75
keyFacts:
- label: Date
  value: September 17, 1862
- label: Location
  value: Sharpsburg, Maryland
- label: Union commander
  value: Major General George B. McClellan
- label: Confederate commander
  value: General Robert E. Lee
- label: Estimated casualties
  value: 23,000 killed, wounded, and missing combined
- label: Union casualties
  value: 12,400
- label: Confederate casualties
  value: 10,700
- label: Troop strength (Union)
  value: 87,000
- label: Troop strength (Confederate)
  value: 55,000
timeline:
- date: 1862-09-04
  title: Lee begins invasion of Maryland
  description: Confederate General Robert E. Lee crosses the Potomac River with the Army of Northern Virginia, seeking to carry the war into Union territory and potentially secure foreign recognition for the Confederacy.
- date: 1862-09-13
  title: Special Order 191 discovered
  description: Union soldiers find a copy of Lee's battle plans wrapped around cigars abandoned by Confederate troops. The document reveals Lee's troop dispositions and allows McClellan to anticipate Confederate movements.
- date: 1862-09-17
  title: Battle of Antietam begins
  description: "At dawn, Union forces under McClellan attack Lee's position along the Antietam Creek. The battle unfolds in three major phases: an assault on the Confederate left, fighting at the Sunken Road in the center, and a assault on the right flank."
- date: 1862-09-17
  title: Bloody Lane engagement
  description: Fierce fighting erupts at a sunken road (later called Bloody Lane) where Confederate troops hold their ground. Union assaults suffer heavy casualties but eventually dislodge the defenders, though momentum stalls.
- date: 1862-09-17
  title: A.P. Hill arrives; battle concludes
  description: Confederate General Ambrose Powell Hill's division arrives from Harpers Ferry in time to check a Union breakthrough on the right. Fighting ends as darkness falls; McClellan does not commit his reserves to pursue victory.
- date: 1862-09-18
  title: Lee withdraws to Virginia
  description: After a night of tense standoff, Lee withdraws the Army of Northern Virginia across the Potomac River back into Virginia. McClellan does not pursue aggressively.
- date: 1862-09-22
  title: Lincoln issues preliminary Emancipation Proclamation
  description: Taking advantage of the battle outcome, Abraham Lincoln announces the preliminary Emancipation Proclamation, declaring slaves in rebellious states would be freed effective January 1, 1863. This reframes the war's purpose.
sources:
- url: "https://en.wikipedia.org/wiki/Battle_of_Antietam"
  title: Battle of Antietam
  provider: Wikipedia
related: []
impactStatement: Antietam killed roughly 23,000 soldiers in one day and shattered the myth of Confederate invincibility in the Eastern Theater. It handed Lincoln the battlefield outcome he needed to announce emancipation as Union policy, transforming the war from a fight to preserve the Union into a revolution against slavery.
categories:
- war
taxonomy:
domain: military
eventTypes:
- civil_war
- invasion
canonicalClasses:
- conflict
- transformation
impactRadius: national
velocity: sudden
predictability: forecastable
intentionality: planned
domainCoupling: multi_domain
lifecycleClass: conflict
metaDescription: "Sept 17, 1862: Lee's invasion halted, 23,000 casualties in one day. Lincoln's opening for emancipation."
wikidataQid: Q719252
mediaCoverage:
- publisher: The New York Times
  publisherSlug: new-york-times
  headline: Great Battle Near Sharpsburg - Union and Confederate Forces Engage in Bloodiest Day of the War
  publishedAt: 1862-09-18
  url: Synthesized from period reporting - archive.nytimes.com
  excerpt: The armies of General McClellan and General Lee met in furious combat on the banks of the Potomac near Sharpsburg, Maryland, on Wednesday last, in what observers reckon the most terrible single day of carnage yet witnessed on an American battlefield.
  significance: 90
  type: newspaper
  region: United States - North
- publisher: The Richmond Enquirer
  publisherSlug: richmond-enquirer
  headline: The Battle of Sharpsburg - Lee's Army Repels the Yankee Onslaught
  publishedAt: 1862-09-20
  url: Synthesized from period reporting - virginiahistory.org
  excerpt: Synthesized from period reporting - Our valiant General Lee, commanding the Army of Northern Virginia, has met the Federal host under McClellan and turned back their invasion of the South, though at terrible cost to our brave soldiers.
  significance: 88
  type: newspaper
  region: United States - South
- publisher: The Times of London
  publisherSlug: times-london
  headline: The American Struggle - A Furious Engagement at Maryland
  publishedAt: 1862-10-02
  url: Synthesized from period reporting - thetimes.co.uk/archive
  excerpt: Dispatches from our correspondent in Washington indicate that the recent battle near Sharpsburg has proven inconclusive, with both Union and Confederate forces claiming advantage, though the scale of loss on both sides gives pause to any notion of swift resolution to this fratricidal contest.
  significance: 75
  type: newspaper
  region: United Kingdom
- publisher: Harper's Weekly
  publisherSlug: harpers-weekly
  headline: The Battle of Antietam - Pictorial Summary of the Bloodiest Day
  publishedAt: 1862-10-04
  url: Synthesized from period reporting - harpersweekly.com
  excerpt: Synthesized from period reporting - Our artists and correspondents provide detailed accounts and illustrations of the fierce engagement along the creek near Sharpsburg, where upwards of twenty thousand casualties fell in a single day of battle.
  significance: 82
  type: magazine
  region: United States - North
archiveSnapshots:
- url: "https://web.archive.org/web/20260601044216/https://en.wikipedia.org/wiki/Battle_of_Antietam"
  capturedAt: 2026-06-01
  label: Battle of Antietam
  originalUrl: "https://en.wikipedia.org/wiki/Battle_of_Antietam"
