The Battle of Antietam was an important battle of the American Civil War. About 50,000 Confederate troops led by General attempted an invasion of the North. They were intercepted on September the 17th, 1862, at Antietam Creek near Sharpsburg by a Union army of 70,000 men under the command of General George Brinton McClellan. In the ensuing action, the Union army suffered about 12,000 casualties, including 2108 killed. Robert E Lee lost some 25 percent of his force; at least 2700 Confederate soldiers were killed and 10,000 were wounded or missing. Robert E Lee's army retreated across the Potomac River the next day, making the outcome technically a Union victory and providing the positive news that President Abraham Lincoln felt was a prerequisite to the issuance of a preliminary Emancipation Proclamation. Research Battle of Antietam