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CASUALTY RECORD // September 14, 1862

Battle of South Mountain

Estimated casualties — killed, wounded, captured, and missing — by side, with confidence labels per surviving record.

Casualties by side

2 sides catalogued · combined 5,010 estimated

  • United States

    2,325

    Medium-confidence figure

  • Confederate States

    2,685

    Medium-confidence figure

Battle context

The Battle of South Mountain was a component engagement of the Maryland Campaign, in which Union forces under McClellan pressed against Confederate positions holding three passes through South Mountain: Crampton's, Turner's, and Fox's Gaps. The engagement involved three separate pitched battles for control of these passes, with Confederate forces under Lee and D. H. Hill contesting a Union force that outnumbered them by roughly 10,000 men. Confederate casualties slightly exceeded Union losses despite the defenders' positional advantage. The battle is known in some early Southern accounts as the Battle of Boonsboro Gap, reflecting the geographic stakes of the contest over mountain passage routes during Lee's incursion into Maryland.

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Last verified June 2026
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