 Atop the Rockpile's is a plateau-like summit that is 40 feet long by 17 feet (12 by 5 m) across at its widest point.The Rockpile was first observed and made note of by a small Marine reconnaissance team on 4 July 1966.The area later became a key outpost from which American and South Vietnamese forces could observe movements by the North Vietnamese Army (NVA) and Viet Cong (VC) troops near the DMZ and in the central and west sectors of northern I Corps.