On Sept. 17, 1862, Union and Confederate forces clashed at the Antietam, one of the most important battles of the Civil War.
Union Army Maj. General George B. McClellan chased Confederate General Robert E. Lee's forces into Maryland. Union forces led an assault on Lee's men, who were occupying a defensive position behind Antietam Creek, thus starting the battle, the first to take place in the Union itself.
The Confederate and Union soldiers fought, each taking the upper hand at times. However, the Union troops were able to force Lee's army out of Maryland back into the Confederacy.
While the victory did little to change the war situation on the ground, it was a widely celebrated victory for the North, and led to a strategic advantage. The battle gave President Lincoln impetus to issue the Emancipation, thus discouraging the British and French from recognizing the Confederacy as an independent nation.
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