[42] The description of Wonsan is based upon: GHQ, FECOM, Military Intelligence Section, General Staff, Theater Intelligence Division, Geographic Branch, _Terrain Study No. 6, Northern Korea_, sec v, 13–16; 1stMarDiv _OpnO 15-50_, annex B, sec 2, 1, 3, 10 Oct 50; and 1stMarDiv _SAR_, annex B (hereafter G-2 _SAR_), sec 2, 1.
Beaches around Wonsan are of moderate gradient, and the floor at water’s edge consists of hard-packed sand. Though slightly wet landings might be expected, amphibious craft could easily negotiate any of the several desirable approaches. The coastal plain, ranging from 100 yards to two miles in depth, provides an acceptable lodgment area, but the seaward wall of the Taebaek mountain range renders inland egress difficult from the military standpoint.
In 1940, the population of Wonsan included 69,115 Koreans and 10,205 Japanese, the latter subsequently being repatriated to their homeland after World War II. Under the Japanese program of industrialization, the city had become Korea’s petroleum refining center. The construction of port facilities, railways, and roads kept pace with the appearance of cracking plants, supporting industries, and huge storage areas.
Two airfields served the locale in 1950. One of these, situated on the coast about five miles north of the seaport, was of minor importance. The other, known as Wonsan Airfield, on Kalma Peninsula across the harbor, ranked high as a military prize. Spacious and accessible, it was an excellent base from which to project air coverage over all of Korea and the Sea of Japan. The Japanese first developed the field as an air adjunct to the naval base at Wonsan; but after World War II, a North Korean aviation unit moved in and used it until July 1950. Thereafter, with the skies dominated by the UN air arm, Wonsan Airfield temporarily lost all military significance. Its vacant runways, barracks, and dispersal areas were given only passing attention in the UN strategic bombing pattern, although the nearby industrial complex was demolished.
In addition to being situated on an excellent harbor, Wonsan is the eastern terminus of the Seoul-Wonsan corridor, the best of the few natural routes across the mountainous nation. This 115-mile road and rail passageway, once considered as a possible overland approach for X Corps, separates the northern and southern divisions of the Taebaek range, which rises precipitously from Korea’s east coast to heights of 5000 feet. Railroads and highways, primitive by western standards, also trace the seaward base of the Taebaek Mountains to connect Wonsan with Hamhung in the north and Pusan far to the south. Still another road and railway leads to Pyongyang, 100 miles across the narrow neck of the peninsula in the western piedmont.