Chapter 5

Offensives and Redeployments: Imperial Lake, Catawba Falls, and Keystone Robin Alpha, July-October 1970

Preliminaries to Imperial Lake-Operation Imperial Lake - Keystone Robin Alpha Redeployments Begin Operation Catawba Falls-The Regiments Realign

Preliminaries to Imperial Lake

While battalions of the 7th Marines swept the hills west of the Thu Bon during Operation Pickens forest, the staffs of the regiment and the 1st Marine Division kept much of their attention fixed further to the cast on the Que Son Mountains. This range, which projects toward the coast from the rugged, jungle-covered mountains of Base Area 112 about 20 miles south of Da Nang, long had constituted a major military problem for the allies. From its hilltops, as Colonel Edmund G. Derning, Jr., commander of the 7th Marines, put it. ''you could see all of Da Nang; you could see any airplane chat took off; you had complete observation ... of the whole terrain up to the north.'1 The canopied ravines and numerous caves of the range sheltered Communist headquarters, hospitals, supply dumps, and training and rest camps- Innumerable infiltration routes connecting hinterland base areas with the coastal rice fields and hamlets ran through the tortuous terrain. Here North Vietnamese regulars and main force Vice Cong often massed for operations in the lowlands, and guerrilla units gathered for training or political indoctrination, A 1st Marine Division staff officer called the Que Sons 'a geographical tragedy .... If those mountains were not there, the war. as far as the NVA or the Viet Cong are concerned, would have been over years ago in Quang Nam Province.'2

Since late spring, the 7th Marines had maintained forces in the Que Sons. The effort began with a multi-company operation by the 3d Battalion in late May and early June which resulted in numerous small contacts and discoveries of enemy camps and hospitals. From the results of this operation. Colonel Doming concluded that 'it didn't take a battalion to go into the Que Son [s].'3 In late June. he proposed, and Major General Widdecke approved, a plan for keeping a reinforced Marine rifle company continually in the mountains.

Thereafter, throughout July and the first pan of August, company after company from the 7th Marines spent five days at a time combing the ridges and ravines. Each company went in by helicopter and was reinforced with an additional rifle platoon, an engineer detachment, and a forward air controller. By day, the company deployed in platoon patrols and ambushes to cover a search area assigned on the basis of current intelligence and reconnaissance information, and by night it pulled into defensive positions. At the end of five days, helicopters would land a relieving company in a zone covered by the out-going unit,4 The companies had many small contacts with enemy parties and uncovered a growing number of installations. In one day, 3 July. for example. Company I of the 3d Battalion killed four NVA in two encounters, lost one Marine killed, and found a large cave containing weapons, food, and medical supplies. Marine commanders believed thai this continuous pressure was disrupting enemy operations by denying the NVA and VC use of their bases.5

In addition to pursuing the VC/NVA aggressively in small-unit patrols, the 7th Marines also developed deceptive measures to conceal the actual movement of units by helicopter within its area of operation. Normal practice was for the troops to board the helicopters, lash in, then sit upright next to the windows (assuming the zone was not hot) as they entered the landing zone. Recognizing thai enemy observers around the Que Sons got fairly accurate troop counts and knew the precise locations of some Marine units, Colonel Derning changed tactics. In a given zone the unit might enter by helicopter with the Marines visible through the windows. Rather than deploy, the Marines would lay down on the floor of the aircraft and the aircraft would exit the zone, giving the impression that a unit had landed. In another zone, the lactic might be reversed with the unit unseen on the way in but visible when extracted. A third option was to keep the Marines concealed on the way into the zone, crawl the unit off quickly, and exit the zone, making it appear thai the helicopter had gone empty both into and out of the zone. Since the enemy had observers throughout the Que Son mountain area, the intent was to confuse the reports to enemy command posts, thus immobilizing or slowing down the movement and reaction time of enemy forces.6

On 5 August, the 7th Marines changed com-