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cut a landing zone, and again search down the fingers. Using this
technique a battalion could search a major ridgeline thoroughly and
in the process discover major enemy trail networks and supply caches.
Both of these search and clear methods proved highly successful in the
operations carried out southwest of Khe Sanh and would become standard
for all future division operations run in the mountainous areas of Quang
Tri Province.

The use of these two search methods resulted in the disclosure of
the enemy's mode of logistical support. The North Vietnamese, it was
discovered, relied heavily on a series ofpre-positioned store sites
and interconnecting trail networks to support his forces. Along a trail
at intervals of about an eight-hour walk apart. Marines would find a
sizeable enemy way station, composed generally of bunkers, supply caches,
huts, and a hospital. Enemy porters apparently would carry supplies
from large depots in Laos or North Vietnam, stopping at a way station
where they would remain hidden during the day and then proceed to the
next station or return for another load. In general, most enemy porters
relied on guides instead of maps and used well-marked, high-speed trails.
"We came to realize," noted General Davis, "that if we were able to
keep Marines on these trails, even from time to time, and were able
to clean out his way stations, destroy his bunkers and his supplies
periodically, that we could severely limit his activity." This realization,
he concluded, "was a major reason for our change in our concept of operation."14

With the end of Operations Robin North and Robin South, the 1st Marines
returned to the task of providing mobile security for Khe Sanh Combat
Base, the surrounding high terrain, Route 9, and supply convoys travelling
the road from Landing Zone Stud to Khe Sanh. Colonel Edward J. Miller's
4th Marines, instead of returning to Camp Carroll, were helilifted to
Ca Lu where a temporary regimental headquarters was established, and
the regiment's battalions were assigned the task of securing vital installations
along Route 9, east from Khe Sanh to Camp Carroll.

In early June the decision was made to deactivate Khe Sanh Combat
Base and shift the major Marine installation in western Quang Tri eastward
to Landing Zone Stud. The 3d Marine Division units were now operating
well beyond the range of Khe Sanh-based artillery, and the base itself
had become more of a liability than an asset since it tied down large
numbers of division troops to defend it, while they might have been
better employed in mobile operations carried out on the pattern of Robin
North and Robin South. Finally, the base presented a large and continuing
target for North Vietnamese attacks, and was no longer considered as
vital to allied defensive plans as it had under those championed by
former MACV commander, General William C. Westmoreland.*

Echoing the views of General Creighton Abrams, who relieved Westmoreland
in mid-June, General Cushman of III MAF, General Rosson of Prov Corps,
and General Davis, the MACV press release noted:

forces must make maximum use of their superior fire power and mobility.
Mobile forces, tied to no specific terrain, must be used to the utmost
to attack, intercept, reinforce or take whatever action is most appropriate
to meet the increased enemy threats. Therefore, we have decided to continue
the mobile posture adopted in western Quang Tri Province with Operation
Pegasus in April. This decision makes the operation of the base at Khe
Sanh unnecessary.15

During the latter days of June as Marine engineers made steady progress
in converting Landing Zone Stud into a permanent forward operating base,
the 1st Marines, now under the command of Colonel Ross T. Dwyer, Jr.,
continued with the evacuation and destruction of Khe Sanh. The regiment
also provided security for Route 9 and Fire Support Bases Shepherd and
Gates, formerly known as Landing Zones Mike and Lima, respectively,
and the development of Landing Zone Hawk. But the enemy, who in the
past had exerted such strenuous efforts to dislodge Marine forces from
the base, now appeared reluctant to let them leave. In a series of sharp
engagements fought during late June and the early days of July, elements
of the 1st and 4th Marines thwarted repeated enemy attempts to break
the security screen around Khe Sanh and Route 9 and disrupt the orderly
deactivation of the base.**

The closing of Khe Sanh marked the definite abandonment of the static
defense concept against North Vietnamese Army units in western Quang
Tri Province. The 3d Marine Division henceforth was committed to what
General Davis termed the "mobile concept" of offensive operations. This
concept, or combination of techniques, was to rely on forward artillery
positions and deep vertical envelopment to carry the war to the enemy
throughout the division's area of operations.

* See the discussion in Chapter 16.

** For a more detailed examination of the deactivation of Khe Sanh
Combat Base, see again Chapter 16.

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