“Of all the days on all the fields where American soldiers have fought, the most terrible by almost any measure was September 17, 1862. The battle waged on that date, close by Antietam Creek at Sharpsburg in western Maryland, took a human toll never exceeded on any other single day in the nation’s history. So intense and sustained was the violence, a man recalled, that for a moment in his mind’s eye the very landscape around him turned red.”
Stephen W. Sears
Landscape Turned Red: The Battle of Antietam
The New York Times coverage from 1862 is online.
America’s bloodiest day:
| Killed: | Union 2,000 | Confederate 1,550 | Total Killed: 3,650 |
| Wounded: | Union 9,550 | Confederate 7,750 | Total Wounded: 17,300 |
| Missing/Captured: | Union 750 | Confederate 1,020 | Total Missing: 1,770 |
| Total: | Union 12,400 | Confederate 10,320 | Total Casualties: 22,720 |
As a rule of thumb, about 20% of the wounded died of their wounds and 30% of the missing had been killed (in the days before dog-tags to identify the dead). Accordingly, an estimate of the total dead from the one-day battle: 7,640.
Source: National Park Service