1862 Battle of Antietam

The Battle of Antietam, fought on September 17, 1862, was a pivotal Civil War clash in Maryland, marking the bloodiest single-day battle in American history with about 23,000 casualties. Union forces, led by General McClellan, confronted Confederate troops under General Lee as they tried to invade the North. Although tactically inconclusive, the Union's ability to halt Lee’s advance gave President Lincoln the opportunity to issue the preliminary Emancipation Proclamation, shifting the war's focus toward ending slavery. The battle's high casualties underscored the war’s brutality and greatly impacted subsequent military and political strategies.