The Antietam Campaign during the Civil War is significant for several reasons. The Battle of Antietam, fought on September 17, 1862, was one of the bloodiest single-day battles in American history, resulting in heavy casualties on both sides. It marked a strategic turning point for the Union, as it halted General Robert E. Lee's invasion of the North. The Union victory provided President Abraham Lincoln the opportunity to issue the Emancipation Proclamation, which transformed the Civil War's focus to include the abolition of slavery alongside preserving the Union. The campaign also bolstered Northern morale during a dire phase of the conflict.