Question: The Battle of Cedar Mountain, also known as Slaughter's Mountain or Cedar Run, took place on August 9, 1862, in Culpeper County, Virginia, as part of the American Civil War, Union forces under which Maj. Gen., that was an American politician from Massachusetts and a Union general during the Civil War, attacked Confederate forces under Maj. Gen. Thomas J. "Stonewall" Jackson near Cedar Mountain?
Sentence (from "Battle of Cedar Mountain"): The battle was the first combat of the Northern Virginia Campaign.
Relevant evidence: No