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 "Battle of Gettysburg"): Union Maj. Gen. George Meade's Army of the Potomac defeated attacks by Confederate Gen. Robert E. Lee's Army of Northern Virginia, halting Lee's invasion of the North.
Relevant evidence: No