On the map of Asia the Korean peninsula resembles a thumb dipping down into the Yellow and Japan seas. For centuries it has been the sore thumb of Asiatic power politics, so that trouble in Korea resulted in a twinge being felt in the capitals of Europe. But small as Korea appears on the map, it is actually about 575 miles in length—a peninsula resembling Florida in shape but having about the area of Minnesota.
Variations in climate are comparable to the gradient from Maine to Georgia along the Atlantic seaboard of the United States. Extremes ranging from summer weather of 105° F. to winter temperatures of 40° below zero have been recorded. A monsoon season of floods is to be expected in July and August, followed by a period when typhoons are a possibility. Altogether, it is a climate which can contribute no little to the difficulties of a mechanized invader.
It would be almost an understatement to say that Korea is mountainous. Few areas of the earth’s surface are so consistently rugged. Bleak cliffs seem to thrust themselves dripping out of the sea on the East Korean littoral. The peaks become higher and more perpendicular as they march inland, until altitudes of 9,000 feet are reached.
The principal chain of mountains extends from the Yalu in the north along the east coast to the Pusan area. Just south of the 38th parallel a spur branches off diagonally to southwest Korea in the region of Mokpu. The remainder of the peninsula consists largely of smaller ranges and foothills.
The few broad valleys are found chiefly on the west coast, which has a good many indentations and estuaries. Here also are most of Korea’s large rivers, flowing west and south. Of little aid to navigation, these streams are broad and deep enough to hamper military operations; and in the monsoon season, floods become a menace.
As if the west coast were paying a penalty for being less mountainous, mud flats and islands hamper navigation. And here the tides are among the highest in the world, with an extreme range of about 30 feet existing at Inchon in contrast to unusually moderate tides along the east coast.
The west and south are the agricultural areas of Korea. Nothing is wasted by peasants who till every inch of the lowland flats, rice paddies, and terraced hills. Due to their back-breaking toil rather than many natural advantages, Korea was able to export as much as half of its two food staples, rice and fish, under the Japanese administration.
The population, estimated at 25,000,000 in 1945, increased both by immigration and a high birth rate during the next 5 years until as many as 29,000,000 inhabitants were claimed. Seoul was a capital of a million and a half residents, and the two leading seaports, Pusan and Inchon, had not far from a quarter of a million each. Modern office buildings, factories and street railways were found in combination with muddy streets and thatched huts on the outskirts.
A standard-gauge rail network, built largely by the Japanese, linked the principal cities and connected in the north with the Manchurian railways. The highway system was good for an Asiatic country but inadequate for the purpose of an invader on wheels and tracks. Hard-surfaced roads were few and far between, and the ordinary earth roads were churned into bogs during the monsoon season. Air transportation was limited to only a few large airfields and emergency landing facilities.
Altogether, Korea promised to be a tough nut to crack, when it came to geography, for the officers poring over maps in Tokyo.