As the regiment noted, the earlier withdrawal of the OPLR had “altered to a considerable extent the tactics employed in this area. This is especially apparent in the number of patrol contacts close to the MLR and displayed the eagerness of the enemy to move in on any ground not held by friendly forces.”[128] At the same time the increased number of troops made available for the MLR defense considerably strengthened the JAMESTOWN Line itself. Sector responsibility changed on 11 May. Colonel Russell E. Honsowetz’ 7th Marines relieved the 5th Marines in the center regimental sector, with 2/7 and 1/7 occupying the left and right battalion positions, respectively. [128] _Ibid._, p. 1. When it took over the peace corridor sector the 7th Marines also assumed the responsibility for emergency rescue of the Allied truce delegates at Panmunjom.[129] The regiment advanced a mile nearer the objective when it moved the pick-up force’s assembly area to within 400 yards of the line of departure. The 7th Marines also replaced the tanks in the force with M-39 personnel carriers, a U.S. Army-developed tracked vehicle similar in appearance to the Marine amphibian tractor. Another vehicle the 7th Marines retained in its task force was a medium tank equipped with additional radios. This armored communication and control vehicle was used as a radio relay station on the MLR to assist in liaison between moving infantry and tank units. Marine riflemen dubbed this command tank the porcupine, to describe the effect of many bristling antennas sticking out from its top. While the Marine division right sector, occupied by the 1st Marines, remained relatively quiet during the spring months on JAMESTOWN, the 7th Marines in the center MLR would shortly be involved in the division’s major ground action in late May. [129] This force and its mission at various times were known as “Task Force Jig” or “Operation Snatch.” As part of the active defense of its JAMESTOWN line, Lieutenant Colonel Daughtry, commanding 1/7, issued a directive on 26 May intended to deny to the enemy key terrain remaining on the old OPLR. Operation Plan 16-52 called for an attack to seize two parcels of high ground to the regiment’s right front. At the same time, the battalion was to neutralize two Chinese positions west of the main objectives, Hill 104 (Objective 1) and the Tumae-ri Ridge (Objective 2), approximately a half-mile further north. The designated attack force, Captain Earl W. Thompson’s Company A, was heavily reinforced. While Company A pursued its mission to the right, a Company C reinforced platoon under Second Lieutenant Howard L. Siers would conduct a feint on a pair of enemy positions to the left. Support for the operation would come from 2/11, two tank platoons, and from air, which was to be on call.