This series of events did not go unnoticed at higher headquarters. General Cushman saw that Colonel Lownds had more on his hands than could be handled by two battalions and directed that 2/26 be transferred to the operational control of its parent unit. On 16 January, 2/26, commanded by Lieutenant Colonel Francis J. Heath, Jr., landed at the Khe Sanh Combat Base; its arrival marked the first time that the three battalions of the 26th Marines had operated together in combat since Iwo Jima. The rapid deployment of Lieutenant Colonel Heath's unit was another example of the speed with which large number of troops could be committed to battle. The regimental commander knew that he would be getting reinforcements but he did not know exactly when they would arrive; he was informed by telephone just as the lead transports were entering the landing pattern. The question that then arose was: "Where could the newcomers do the most good?"(37) Outside of the combat base itself, there were several areas which were vital. The most critical points were the hill outposts, because both General Tompkins and Colonel Lownds were well aware of what had happened at Dien Bien Phu when the Viet Minh owned the mountains and the French owned the valley. It was essential that the hills around Khe Sanh remain in the hands of the Marines. Shortly after its arrival in mid-December 1967, 3/26 had relieved 1/26 of most of this responsibility. Company I, 3/26, along with a three-gun detachment of 105mm howitzers from Battery C, 1/13, was situated atop Hill 881S; Company K, 3/26, with two 4.2-inch mortars, was entrenched on Hill 861; and the 2d Platoon, A/1/26 defended the radio-relay site on Hill 950. This arrangement still left the NVA with an excellent avenue of approach through the Rao Quan Valley which runs between Hills 861 and 950. The regimental commander decided to plug that gap with the newly arrived 2d Battalion.(38) At 1400 the day it arrived, Company F, 2/26, conducted a tactical march to Hill 558--a small knob which sat squarely in the middle of the northwestern approach. The rest of the battalion spent the night in an assembly area approximately 1,300 meters west of the airstrip. The following day, Lieutenant Colonel Heath moved his three remaining companies and the CP group overland to join Company F. Once the Marines were dug in, the perimeter completely encompassed Hill 558 and blocked enemy movement through the Rao Quan Valley.(39)