Plei Trap Valley - Closing the Plei Trap Road


Lieutenant Colonel Elvin R. Eeiberg IIL United States Army

IN THE Central Highlands of Vietnam, the enemy threat in late 1968 was posed by main force North Vietnamese Army (NVA) elements. These units moved either against the population centers of the highlands - Dak To, Kontum, Pleiku, and Banmethuot or used the terrain to move troops and supplies east or south toward the coastal areas.  

Much of the heavy movement was along a vehicular road just to the east of the Cambodian-South Vietnamese border. The road varies in width from three to five yards, and every low spot and stream crossing is provided with a bridge, culverts or corduroyed ford. Sidehill cuts are revetted, and steep shoulders are marked by sturdy wooden stakes. About every 55 yards, there is a three or four-man proactive bunker since US air and artillery interdiction is a common occurrence. The road is generally viewable from the air because the numerous interdiction missions have killed the trees which although largely erect have shad their leaves.  

Through October 1968, it increasingly became apparent that the NVA were making extensive nightly use of the road. Foot traffic was heavy, and vehicular traffic including 1.5 ton trucks, was detected. The road had become virtually impassable for wheeled use during the June and September highland monsoon season, but had since been rehabilitated by NVA engineers who relied chiefly on hand labor.

The US 4th Infantry Division used all appropriate reconnaissance detection means along the route, chiefly helicopter and fixed-wing aircraft but also long-range reconnaissance patrols (LRRP’s) near the trail. Photos and reports by the LRRP’e confirmed the heavy feat and truck traffic. The commanding general of the 1st Field Force Vietnam directed that the road be closed.  

Considerable experience indicated that air and artillery interdiction could close sections of the road only temporarily. The resulting craters and randomly felled trees were removed or bypassed by the next morning. The lip of a 750-pound bomb crater was simply used on the new road after some reshaping and the installation of posts to mark the crater’s edge. Free World troupes would have to move onto the road to close it.  

In early November, the 4th Division engineer made aerial reconnaissance flights to determine a course of action to recommend. The reconnaissance revealed one stretch of road, just east of the Cambodian border, where a “chokepoint” existed. This stretch was vulnerable to engineer demolition. The road here, after crossing the border to the south, crossed a fairly wide stream, wound up a narrow valley into a saddle, over this saddle south into the Plei Trap Valley along a sidehill cut, and then onto the valley flat land.  

The stretch between the stream and the valley was about two mile long and offered a number of small stream crossings for craters and ford destruction work several hundred yards of rod flanked by huge dead mahogany trees, and the vulnerable sidehill cut leading into the valley. A detour around the pass was not possible without a tremendous construction effort or a lengthy road rerouting west of the border.  

An equally important consideration was the provision of effective fire support for the troops on the ground. Two existing land connections, Route 511, was closed in July 196S, it could be reopened with the installation of a 109-yard bridge, repair work on the road, and minesweeping.  

The 4th Infantry Division commander decided to conduct a one-week operation based out of Polei Kleng to former 4th Division firebases existed within accurate howitzer range of the chokepoint. Although both bases would require rehabilitating, the 4tb Division forces were well practiced in techniques of rapid firebase construction on seemingly inaccessible terrain.  

Since the two Firebases and the Plei Trap Road could only he reached by helicopter, a lift base was required to support the operation. The closest base - and, therefore meet attractive from the standpoint of consuming helicopter flying time was the Polei Kleng Special Forces Camp. The camp had a good C-7A strip, and, while the permit the engineers sufficient time to close the NVA route. He instructed his engineers to close the road in such a manner that attempts to reopen it would be immediately detected from the air. He directed the 2d Brigade to execute the operation in conjunction with an Army Republic of Vietnam (ARVN) paramilitary force.  

This ARVN element was composed of five Camp Strike Force (CSF) companies stationed at various camps throughout the highlands. The 2d Brigade had available its own direct support engineer company C, 4th Engineers; a detachment from Company A; and elements of Headquarters Company.

Polei Kleng was opened by 20 November after a 21-float M4T6 pontoon bridge bad been built and the necessary work on the road had been done. Some work was required at the camp to prepare it for the influx of CSF, the brigade, artillery, and support troops. The detachment from company A, which would construct a critical abatis at the chokepoint underwent training in airmobile techniques, cratering , and tree felling.  

During the week before the start of the operation, an extensive air and artillery interdiction program continued along the road. At the request of the engineers, the pass area of the chokepoint was untouched, so as not to complicate rapid engineer deployment in the area.


Map Central Highlands Vietnam