I have often suspected that our main purpose was just to wander around until we found them - or they found us. Once in contact all we, as the sacrificial grunts, had to do was hold them there until we could get artillary or airpower on them.
The following article is taken from a government history of the Vietnam war. It is about operation Oklahoma Hills. It turns out we weren't always just wandering aimlessly. There were at least some reasons to go where we went, reasonably often we found what was expected.
I still think they could have passed the word on to us at least some of the time.
This is very lengthy. In places you will find where I have inserted comments in red text.
The large mountainous region west of Da Nang, ecompassing such well-known areas as Charlie Ridge and Happy Valley, had long been suspected as a region that not only harbored enemy troops, but major base camps and infiltration routes, all of which posed direct and ever-present threat to the Da Nang Vital Area. Considerable information on those routes had accumulated since October 1968 when the last major Marine operations in the area, Mameluke Thrust and Maui Peak, ended. Defectors and prisoners of war captured during operation Taylor Common and subsequent operations around Da Nang and throughout the An Hoi basin during Tet provided additional information.
One such prisoner, the senior captain and temporary commander of the 141st Regiment, captured by Lt. Col. Quinn's 3rd Bn., 7th Marines during the heavy fighting around Hill 41 on February 23, furnished intelligence on the major base camps and infiltration routes leading toward Da Nang and An Hoa. During his extensive interrogation, he related that the major supply routes for the 141st NVA Regt., and in all probability the 31st Infantry and 368B Artillery Regts. originated far to the west in the Ai Yen area, 20 kilometers east of the Laotian border, and could be traced east along Route 614. At the point where the road dividedwest of the Song Con, (Song is Vietnamese for river) one supply route continued east along 614 into Happy Valley, while the other route began at the meeting of the Song Con and Route 614 and followed the river south to its intersections with the Song Yang at An Dien, eight kilometers northeast of Thuong Duc, and then east to the Song Vu Gia (Song Vu Gai is the river that ran under Liberty Bridge). From there supplies and men were either diverted to Base Area 112 and then into the northen Arizona or north onto Charlie Ridge and into Happy Valley, From the terminus of Route 614 in Happy Valley, the enemy shifting supplies and men to units operating near the Song Tuy Loan (This is the river that flowed under Cobb Bridge), or to other units located in the northeast Charlie Ridge-Sherwood Forest-Worth Ridge area, overlooking Da Nang
Enemy infiltration and supply routes described by other prisoners of war and ralliers were of a general nature, but two common areas continued to emerge - Charlie Ridge and Happy Valley. Both regions contained not only major enemy suply routes, but also suspected base camps and storage facilities at the terminus of those routes. Both were to become prime targets for the Marines of the 1st Div. As Col. Robert L. Nichols, (Most of the time I couldn't have told you who the Bn. commander was, let alone the Regt. commander, what difference would it have made to me?)who replaced Col. Beckington as Commanding Officer of the 7th Marines on February noted: "This terrain mass has provided a haven for the enemy in which he could assemble his forces and institute his infiltration tactic into the Da Nang Vital Area. Of particular concern in recent months has been his tactic of using this infiltration approach to launch rockets into the Da Nang Vital Area."
Once Task Force Yankee had neutralized Base Area 112 and secured the southern flank of the Thuong Duc corridor as a result of operation Taylor Common, clearing the hills west of Da Nang and securing both the western approaches to the vital area and northern flank of the Thuong Duc corridor was the next logical step.
First Div. Marines would find it difficult operating within the region, Both Charlie Ridge and Worth Ridge were high, narrow ranges, cut by numerous steep-sided valleys, ravines, and gorges, and covered my multi-caonpied jungle, and dense undergrowth. Movement throughout Happy Valley, blanketed by dense underbush and elephant grass 7 to 10 feet high, likewise would be arduous. The irregular terrain and density of vegetation would thus make foot movement a necessity, but yet impede it. Supporting arms would have to be used sparingly because of the dense overhead cover, and helicopter operations, especially medical evacuations, would have to be restricted due to the lack of suitable landing zones. (It was extremly thick. As far as I can remeber every LZ had to be made by blasting the trees down.) Although terrain often favored the enemy, in this case, both Marine and NVA soldiers would be on equal footing, as Col. James B. Ord, Jr noted:
The enemy always has the advantage, as I see it, of operating in the jungle, in the
canopy. You only get a point to point contact. You cannot maneuver on a broad
front, so you are on a parity with him as far as the infantry is concerned. Since
your observation is limited and your fields of fire are limited, it is difficult to make
use of supporting arms in which we have a distinct advantage. And the enemy can
always break contact and he can always evade. And so this being the case, wer are
just about equal: we have no advantage.
The initial concept of operations, as outlined by Gen. Simpson, called for two Battalions of Nichols' 7th Marines to be helilifted into the southwestern and northwestern portions of the area of operations, on battalion to attack northwest from Hill 52 (In Happy Valley along Song Vu Gia) along Route 4, and the other to attack south from R.C. Ba Na, Hill 467, overlooking Happy Valley. A third battalion was to attack west along the axis of Worth Ridge and Charlie Ridge, placing pressure on the enemy from all directions. As the 7th Marines began planning for the operation, a number of potential problems arose. A landing R.C. Ba Na, followed by a sweep south from the ridge onto Charlie Ridge would be hazardous and time-comsuming due to the rough terrain. In addition, the 3rd Bn. would find it difficult to conduct effective search and destroy operations over the broad expanse of terrain formed by Charlie and Worth Ridges.