Which battle is known as the bloodiest single-day battle in American history?

The Battle of Antietam is recognized as the bloodiest single-day battle in American history. Fought on September 17, 1862, during the American Civil War, this battle resulted in approximately 23,000 casualties in just one day of fighting. The high number of deaths and injuries was due to the intense combat that took place in a relatively short timeframe, making it a significant event not just for its immediate military outcomes but also for its broader implications.

Antietam became a pivotal moment in the war, as it halted the advance of Confederate General Robert E. Lee's army into the North. This strategic victory for Union General George McClellan gave President Abraham Lincoln the opportunity to issue the Emancipation Proclamation, on the basis that the Union had seen a much-needed victory, even if it wasn’t a complete military triumph. Thus, the Battle of Antietam is viewed as a turning point in the Civil War, emphasizing the heavy costs of war and the ongoing struggles over issues such as slavery and national unity.