How many people really died because of the Civil War? And why does it matter?

(NYTimes) Even as Civil War history has gone through several cycles of revision, one thing has remained fixed: the number of dead. Since about 1900, historians and the general public have assumed that 618,222 men died on both sides. That number is probably a significant undercount, however. New estimates, based on Census data, indicate that the death toll was approximately 750,000, and may have been as high as 850,000. Continued