Which best states why the Battle of Antietam was considered a turning point in the Civil War?

Antietam was the bloodiest single day in U.S. history, with roughly 23,000 Union and Confederate casualties. Its high loss of life made it a major turning point, and the Union’s claim of a strategic victory also gave President Lincoln the opportunity to issue the Emancipation Proclamation. The Anaconda Plan was a Union strategy, not one adopted by the South.

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