Department of Defense (USMC) Photo A801132
An aerial view of the Marble Mountain Air Facility and base on Tiensha Peninsula across the river from the main airbase at Da Nang, which can be seen vaguely in the background to the right. Marble Mountain was home to the helicopters of Marine aircraft group based there.
In order to secure the approaches to the city and the nearby Da Nang Airbase, the 1st Marine Division had divided the sector into several defensive zones and tactical areas of operation. The city itselt, the Da Nang Airbase, and the Marble Mountain helicopter facility on the Tiensha Peninsula across the Han River from Da Nang and the main air base constituted the Da Nang Vital Area. In the immediate area west ot the city and the airbase, the Marines had established two defensive command sectors, the northern and southern. Under the operational control of the 11th Marines, the division artillery regiment, the Northern Sector Defense Command (NSDC), composed of troops from various headquarters and support units, encompassed the division command post on Hill 327 (called Division Ridge), the northern artillery cantonment, and the Force Logistic Command on Red Beach. Bounded by the Cu De River on the north and the Southern Sector Defense Command (SSDC) on the south, a distance of some 10 kilometers, the northern sector command in cooperation with its tenant units manned the fixed defenses and ran patrols in the surrounding paddies, scrub brush, and low-lying hills to the west. Similarly, the Southern Sector Defense Command, under the operational control ut the 1st Tank Battalion, covered the southern and southwestern