Steep-sided hills and mountains, which sloped abruptly into narrow valleys pierced by many of the rivers and larger streams, predominated the terrain in the I Corps sector where the Marines located. The most rugged terrain was to the rear of the JAMESTOWN Line; six miles northeast of the Munsan-ni railhead was a 1,948-foot mountain, far higher than any other elevation on the Marine or Chinese MLR but lower than the rear area peaks supporting the Communist defenses. Ground cover in the division sector consisted of grass, scrub brush, and, occasionally, small trees. Rice fields crowded the valley floors. Mud flats were prevalent in many areas immediately adjacent to the larger rivers which intersected the division territory or virtually paralleled the east and western boundaries of the Marine sector.
The transfer from the Punchbowl in the east to western Korea thus resulted in a distinct change of scene for the Marines, who went from a rugged mountainous area to comparatively level terrain. Instead of facing a line held by predominantly North Korean forces the division was now confronted by the Chinese Communists. The Marines also went from a front that had been characterized by lively patrol action to one that in March 1952 was relatively dormant. With the arrival of the 1st Marine Division, this critical I Corps sector would witness sharply renewed activity and become a focal point of action in the UNC line.
Organization of the 1st Marine Division Area[18]
[18] Unless otherwise noted, the material in this section is derived from: PacFlt EvalRpt No. 4, Chap. 9; 1stMarDiv, 1stMar, 5thMar, 7thMar, 11thMar ComdDs, Mar 52; 1st KMC RCT Daily Intelligence and Operations Rpts, hereafter KMC Regt UnitRpts, Mar 52; Kimpo ProvRegt ComdDs, hereafter KPR ComdDs, Mar-Apr 52.
“To defend” were the key words in the 1st Marine Division mission—“to organize, occupy, and actively defend its sector of Line JAMESTOWN”—in West Korea. General Selden’s force to prevent enemy penetration of JAMESTOWN numbered 1,364 Marine officers, 24,846 enlisted Marines, 1,100 naval personnel, and 4,400 Koreans of the attached 1st KMC Regiment. The division also had operational control of several I Corps reinforcing artillery units in its sector. On 31 March, another major infantry unit, the Kimpo Provisional Regiment (KPR) was organized. The division then assumed responsibility for the Kimpo Peninsula defense on the west flank with this Marine-Korean force.
A major reason for transfer of the 1st Marine Division to the west, it will be remembered, had been the weakness of the Kimpo defense. Several units, the 5th KMC Battalion, the Marine 1st Armored Amphibian Battalion, and the 13th ROK Security Battalion (less one company), had been charged with the protection of the peninsula. Their operations, although coordinated by I Corps, were conducted independently. The fixed nature of the Kimpo defenses provided for neither a reserve maneuver element to help repel any enemy action that might develop nor a single commander to coordinate the operations of the defending units.
These weaknesses become more critical in consideration of the type of facilities at Kimpo and their proximity to the South Korean Capital. Seoul lay just east of the base of Kimpo Peninsula, separated from it only by the Han River. Located on Kimpo was the key port of Inchon and two other vital installations, the logistical complex at Ascom City and the Kimpo Airfield (K-14). All of these facilities were indispensable to the United Nations Command.
To improve the security of Kimpo and provide a cohesive, integrated defense line, CG, 1st Marine Division formed the independent commands into the Kimpo Provisional Regiment. Colonel Edward M. Staab, Jr., was named the first KPR commander. His small headquarters functioned in a tactical capacity only without major administrative duties. The detachments that comprised the KPR upon its formation were:
Headquarters and Service Company, with regimental and company headquarters and a communication platoon;
1st Armored Amphibian Battalion, as supporting artillery;