Antietam MD003
1862-09-16 to 1862-09-18 · MD · Maryland Campaign [September 1862] · frozen result: Inconclusive · NPS summary (as listed)
On September 16, Maj. Gen. George B. McClellan confronted Lee's Army of Northern Virginia at Sharpsburg, Maryland. At dawn September 17, Hooker's corps mounted a powerful assault on Lee's left flank that began the single bloodiest day in American military history. 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. Late in the day, Burnside's corps finally got into action, crossing the stone bridge over Antietam Creek and rolling up the Confederate right. At a crucial moment, A.P. Hill's division arrived from Harpers Ferry and counterattacked, driving back Burnside and saving the day. 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 the 18th, while removing his wounded south of the river. McClellan did not renew the assaults. After dark, Lee ordered the battered Army of Northern Virginia to withdraw across the Potomac into the Shenandoah Valley.
Dossier claims
Draft dossier, revision antietam-review-correction-2026-10-06. Claims are extraction records with their quoted passages, not historical adjudication. JSON
information
unknownunresolved
Not established by the sources inspected for this draft.
logistics
unknownunresolved
Not established by the sources inspected for this draft.
objectives
unknownunresolved
Not established by the sources inspected for this draft.
outcome
supportedpost_outcome The frozen CWSAC result is Inconclusive; its result text adds a Union strategic victory. The NPS page as retrieved on 2026-09-20 gives Indecisive and does not carry the strategic label.
Retain the frozen result value Inconclusive. The parenthetical is a strategic label, not a tactical result: do not relabel the tactical outcome to fit it, and do not read the live page's omission as a contradiction. All three cells are in the nps-cwsac group, so they are not independent corroboration.
Inconclusive (Union strategic victory.)arnold-cwsac-battles, battle MD003; column results_text · snapshot
952b5d08402a…supportedpost_outcome NPS records that after dark, following skirmishing throughout the 18th, Lee ordered the Army of Northern Virginia to withdraw across the Potomac.
Campaign consequences need a separate outcome definition.
disputedpost_outcome The frozen casualty text reads 23,100 total; the NPS field as retrieved on 2026-09-20 reads 22700 total (US 12400; CS 10300;).
Original casualty returns were not inspected; preserve both totals and their difference without averaging or reconciliation. No casualty-based opening count. Both records are in the nps-cwsac group, so they are not independent.
responsibility
supportedunresolved NPS lists McClellan (US) and Lee (CS) as principal commanders and displays both as Major General. Its narrative attributes the commitment decisions to them: Lee committed his entire force, while McClellan sent in less than three-quarters of his army and did not renew the assaults.
This is a modern NPS narrative attribution, not a contemporary record. It names army-level decisions; it does not measure each commander's contribution. NPS's 'enabling Lee to fight the Federals to a standstill' remains its interpretation, not an established causal effect. The corps and division actions it names (Hooker, Burnside, A.P. Hill) are not attributed to the army commanders. The displayed rank is a structured field that needs scrutiny: the frozen arnold-cwsac-commanders row gives Lee as General.
Lee committed his entire force, while McClellan sent in less than three-quarters of his armynps-md003, Description · snapshot
d71c7a983804…Generalarnold-cwsac-commanders, battle MD003, belligerent Confederate, fullname Robert E. Lee; column rank · snapshot
6c587c298717…strength
disputedunresolved The NPS page as retrieved on 2026-09-20 displays zero troops on both sides; treat this as an unresolved source-data problem.
A zero displayed in a populated historical battle page is not a valid measured force estimate. The frozen CWSAC row has no numeric strength (blank strength, blank force rows); a missing value is not a zero.
supportedunresolved The same page describes numerical asymmetry and partial commitment of the Union army.
This conflicts with the displayed zeros and distinguishes available from committed troops; it does not establish a numerical count. NPS does not state whether the two-to-one ratio refers to present, available or engaged troops.
terrain
supportedunresolved NPS places the fighting at Miller's cornfield, the Dunker Church and the Sunken Road, and has Burnside's corps crossing the stone bridge over Antietam Creek.
A modern NPS narrative that names features but does not describe ground, cover or their tactical effect, which remain unknown. It also does not show that any commander chose or created these conditions.
Attacks and counterattacks swept across Miller's cornfield and fighting swirled around the Dunker Churchnps-md003, Description · snapshot
d71c7a983804…Open questions
- Reconstruct present, available, and engaged strengths for each side from independent sources.
- Define tactical and campaign outcomes before assigning numeric utilities.
- Investigate the provenance of the live-page zeros; do not overwrite the archived source.