Why were more Americans killed in the civil war than all US wars combined?

More Americans were killed in the Civil War than in all other U.S. wars combined due to the war's unprecedented scale and intensity, as well as the lack of advanced medical care and technology at the time. The conflict saw brutal battles with massive numbers of soldiers engaged, leading to high casualty rates. Additionally, diseases and poor sanitary conditions contributed significantly to the death toll, with many soldiers succumbing to illness rather than direct combat. The Civil War's deep social and political ramifications also meant that it pitted Americans against each other in a way that intensified the conflict's lethality.