Question: What  battle of the Civil War involved the largest number of casualties of the entire war and is often described as the war's turning point, Second Battle of Bull Run or Battle of Gettysburg?
Sentence (from "Eric J. Wittenberg"): His published works have focused especially on the Civil War cavalryman and the cavalry battles of the Civil War, with emphasis on the Army of the Potomac's Cavalry Corps.
Relevant evidence: No