I know there were a great many casualties in the Civil War - but isnt that ratio on the high side?
The number of men who died during the Civil War: I include those who died of “camp diseases” (deaths due to the spread of diseases in military camps involving as they did assembleges of men from various places), as does Jeffrey Rogers Hummel.
https://www.amazon.com/Emancipating-Slaves-Enslaving-Free-Men/dp/0812693124