The main reason for concern, however, was the testimony of the cooperative NVA lieutenant who had surrendered on the 20th. According to the lieutenant, the eastern avenue of approach was the key with which the Communists hoped to unlock the Khe Sanh defenses. First, the NVA intended to attack and seize Hills 861 and 881S, both of which would serve as fire support bases. From these commanding positions, the enemy would push into the valley and apply pressure along the northern and western portion of the Marines' perimeter. These efforts, however, were simply a diversion to conceal the main thrust--a regimental ground attack from the opposite quarter. An assault regiment from the =304th Division= would skirt the base to the south, hook around to the east, and attack paralleling the runway through the 1/26 lines. [Illustration: Two key figures in the defense of Khe Sanh: Major General Rathvon McC. Tompkins (L), CG, 3d MarDiv, and Colonel David E. Lownds (R), CO, 26th Marines. (Photo courtesy Colonel David E. Lownds)] [Illustration: General Tompkins (L) made helicopter trips into Khe Sanh almost daily in spite of heavy enemy fire. (Photo courtesy David D. Duncan)] [Illustration: MAP 6 LOCATION OF OUTPOSTS E. L. WILSON] Once the compound was penetrated, the North Vietnamese anticipated that the entire Marine defense system would collapse.(69) On 27 January, the 37th ARVN Ranger Battalion, the fifth and final battalion allotted for Khe Sanh, arrived.[24](70) Understandably, Colonel Lownds moved the ARVN unit into the eastern portion of the perimeter to reinforce the 1st Battalion. Actually, the Marines were backing-up the South Vietnamese because the Ranger Battalion occupied trenches some 200 meters outside the 1/26 lines. Lieutenant Colonel Wilkinson's men had already prepared these defensive positions for the new arrivals. The new trenchline extended from the northeast corner of Blue Sector, looped across the runway, paralleled the inner trenchline of 1/26, and tied back in with the Marine lines on the southeastern corner of Grey Sector. (See Map 7) The only gap was where the runway extended through the ARVN lines; this section was covered by two Ontos. At night, the gap was sealed off with strands of German Tape--a new type of razor-sharp barbed wire which was extremely difficult to breach. The North Vietnamese would now have to penetrate two lines of defense if they approached from the east.(71)