Frontline units, from the west, were the 1st KMCs, the 5th, and 1st Marines. To the rear, the 7th Marines, designated as division reserve, together with organic and attached units of the division, had established an extensive support and supply area. As a temporary measure, a battalion of the division reserve, 2/7, was detached for defense of the Kimpo Peninsula pending a reorganization of forces in this area. Major logistical facilities were the division airhead, located at K-16 airfield, just southwest of Seoul, and the railhead at Munsan-ni, 25 miles northwest of the capital city and about five miles to the rear of the division sector at its nearest point. Forward of the 1st Marine Division line, outposts were established to enhance the division’s security. In the rear area the support facilities, secondary defense lines, and unit command posts kept pace with development of defensive installations on the MLR. Throughout the 1st Marine Division sector outpost security, field fortifications, and the ground defense net were thorough and intended to deny the enemy access to Seoul. _The Marines’ Home in Western Korea_[16] [16] Unless otherwise noted, the material in this section is derived from: 1stMarDiv ComdD, Mar 52; CIA, _NIS 41B_, South Korea, Chap I, Brief, Section 21, Military Geographic Regions, Section 24, Topography (Washington: 1957–1962); Map, Korea, 1:50,000, AMS Series L 751, Sheets 6526 I and IV, 6527 I, II, III, and IV, 6528 II and III, 6627 III and IV, and 6628 III (prepared by the Engineer, HQ, AFFE, and AFFE/8A, 1952–1954). In western Korea, the home of the 1st Marine Division lay in a particularly significant area. (See Map 2.) Within the Marine boundaries ran the route that invaders through the ages had used in their drive south to Seoul. It was the 1st Marine Division’s mission to block any such future attempts. One of the reasons for moving the Marines to the west[17] was that the terrain there had to be held at all costs; land in the east, mountainous and less valuable, could better be sacrificed if a partial withdrawal in Korea became necessary. At the end of March 1952, the division main line of resistance stretched across difficult terrain for more than 30 miles, from Kimpo to the British Commonwealth sector on the east, a frontage far in excess of the textbook concept.