For the battle of Atlanta, 10,000 soldiers and civilians.
Source: Statistical Record of the Armies of the United States, Frederick Phisterer.
Ten thousand total causalties? That would place it well behind the casualty count for Antietam and Gettysburg and Shiloh. I haven't seen anything that would indicated 10,000 dead at Atlanta. What's your point? Are you claiming that there were thousands of civilians killed at Atlanta? Where is your evidence for that? Not even Fellman claims that, and he's about as hard on Sherman as any biographer is.