direction" over Marine fixed-wing aircraft. Despite Marine Corps protests, Westmoreland's order prevailed. While obtaining major modifications to the ruling, Marine air in Vietnam would operate under the single manager system to the end of the U.S. involvement in Vietnam.
With the end of the enemy offensive, the allies planned to breakout from Khe Sanh. While North Vietnamese ground forces did not follow up on their Lang Vei attack, they incessantly probed the hill outposts and perimeter. Employing innovative air tactics, Marine and Air Force transport and helicopter pilots kept the base supplied. Finally on 14 April, the U.S. 1st Cavalry Division reinforced by a Marine regiment relieved the base. On 14 April, the 77-day "siege" of Khe Sanh was over.
The North Vietnamese were far from defeated, however, and in early May launched their "mini-Tet offensive." Except for increased fighting in the capital city of Saigon and the heavy fighting in the eastern DMZ sector, the North Vietnamese May offensive was largely limited to attacks by fire at allied bases and acts of terrorism in the hamlets and villages. In I Corps, the major attempt was to cut the supply lines in the DMZ sector which led to the very bloody fighting at Dai Do and around Dong Ha. The result again, however, was the defeat of the North Vietnamese forces.
By mid-1968, the allied forces were on the offensive throughout I Corps. General Abrams had succeeded General Westmoreland as Commander, USMACV. Unlike Westmoreland, Abrams had little or no commitment to either keeping a garrison at Khe Sanh or to the barrier. The closing out of the base at Khe Sanh in July 1968 permitted the 3d Marine Division under Major General Raymond G. Davis to launch a series of mobile firebase operations ranging the length and breadth of the northern border area. Long neglected, the barrier concept was officially abandoned in October.
In the late summer of 1968, the Communists launched another "mini-Tet" offensive, but were again bloodily repulsed. By the end of 1968, both the 3d Marine and 1st Marine Divisions were conducting large mobile operations. After a standstill for most of the year, Marine measurements of pacification showed progress in regaining the countryside. In December, enemy-initiated attacks fell to the lowest level in over two years.
Still, no one was about to predict victory and the Communists were far from defeated. The various "Tet" offensives had provided a benchmark for both sides, forcing both to reassess their strategies. After the last "mini-Tet," the North Vietnamese and Viet Cong scaled down their large-unit war, probably out of both weakness and the expectation that the Americans would eventually withdraw. While Tet was a military setback for the Communist forces with the decimation of the Viet Cong and many of their political cadre in the South, the American government, people, and military establishment also realized that there was a limit to American participation in the war. As Marine Lieutenant General John R. Chaisson, later stated, the Marine Corps "had adopted from 1969 on, the idea that we were in the postwar period."1