659 thousand? Quite the coincidence of what he's talking about and this post.

u/#q659

The American Civil War is noted for being the deadliest conflict in U.S. history. Estimates of the number of deaths vary, but a commonly cited figure is around 620,000 soldiers. However, more recent research, particularly by historian J. David Hacker, suggests this number might be significantly higher, potentially ranging from 650,000 to 850,000 when considering both combat and disease-related deaths. This higher estimate reflects a reassessment using demographic methods on census data from the 19th century.