One of the reasons for the high casualty rate at the Battle of Antietam was the combination of advanced weaponry and tactics used by both sides.

The battlefield was marked by the introduction of rifled muskets and artillery, which significantly increased the range and accuracy of fire. Union and Confederate forces engaged in close-quarter combat across open fields, leading to devastating losses. Additionally, the tactical decisions made, including frontal assaults against fortified positions, exacerbated the situation. The clash of outdated tactics with modern weaponry resulted in approximately 22,000 casualties, making Antietam one of the bloodiest battles in American history.