Conversation so far:
What happened in western Virginia to William McKinley during the Civil War?
McKinley and the 23rd Ohio, led by Colonel Eliakim P. Scammon, set out for western Virginia in July 1861 as a part of the Kanawha Division.
Who were William McKinley's enemy in conflicts in western Virginia?
The Army of Northern Virginia was the enemy of Union forces.
Did The Union win the Second Battle of Bull Run?
The Union lost the Second Battle of Bull Run to the Confederacy.

Question: what happened in antietam?
Self-contained rewrite: What happened in Antietam to William McKinley?