What Was the Single Bloodiest Day in American Military History?

On September 17, 1862, the American Civil War saw its bloodiest day on the fields near Antietam Creek in Sharpsburg, Maryland.


The Confederate Army, led by General Robert E. Lee, had invaded Maryland with the hope of winning a decisive battle on Union soil. The Union Army, under General George B. McClellan, intercepted Lee’s army at Antietam Creek and prepared for battle.

The Battle Begins

The battle started early in the morning with Confederate soldiers attacking the Union forces. The fighting was fierce and both sides suffered heavy casualties. By noon, more than 8,000 soldiers had been killed or wounded.

The Sunken Road

One of the most brutal parts of the battle took place at a sunken road that ran through the battlefield. Confederate soldiers used this road as cover while firing at Union soldiers.

The Union troops tried to advance but were met with heavy fire and suffered tremendous losses. This part of the battle became known as “Bloody Lane.”

The Aftermath

By nightfall, both sides had suffered massive casualties. The Confederacy had lost around 10,300 soldiers while the Union lost around 12,400 soldiers. In total, over 22,700 men were killed or wounded in just one day of fighting.

  • Confederate casualties: around 10,300
  • Union casualties: around 12,400
  • Total casualties: over 22,700

The Impact

Despite being a tactical draw (neither side gained any significant advantage), the Battle of Antietam was a turning point in the Civil War. It gave President Abraham Lincoln enough confidence to issue his Emancipation Proclamation which declared all slaves in Confederate-held territories to be free.


The Battle of Antietam was the bloodiest day in American military history, with more casualties than any other single day battle. It remains a tragic reminder of the human cost of war and the sacrifices made by those who fought for their beliefs. The bravery and sacrifice of those who fought at Antietam will never be forgotten.