Number of soldiers killed in US Civil War?

Combatants in the US Civil War:

United States of America (Union)

Commanders: Abraham Lincoln, Ulysses S. Grant

Strength: 2,200,000

Confederate States of America (Confederacy)

Commanders: Jefferson Davis, Robert Edward Lee

Strength: 1,064,000

Despite this disparity in troop strength, armies of comparable size met on several battlefields. Much of the Union Army was scattered from the West to the Atlantic coast in defensive positions. Much more of the Confederate strength was in the large mobile fighting forces.