The recent role of Korea as the battle-ground between the Communist land-powers, Russia and China, and the forces of the United Nations, based initially upon Japan and maintained in the field by western sea power, is the latest among many manifestations of a problem which is inherent in the geography of the country. Owing to its character as a land bridge, projecting some 600 miles from the parent continental mass to within 120 miles or so of the Japanese archipelago, Korea has been the scene of repeated move? ment between the two. Both the northern Mongoloid strain in the present Japanese population and the broad stream of Chinese culture which flowed into the islands during the first millennium a.d. passed this way; again in 1274 and 1281 Kublai Khan used the peninsula as the springboard for his attempted invasions of Japan, and over three hundred years later Hideyoshi reversed the process in what proved to be an equally abortive attack on China. In respect of its internal geography Korea was likened by Karl Ritter to Italy, but from many points of view the comparison with Japan is more significant. Geologically it is an area of ancient folding much modified by more recent dislocation and endowed with considerable mineral wealth, especially in the north. Like Japan moreover it is predominantly mountainous, with a series of rugged transverse ridges separating it from the Manchurian lowlands and an axial range1 running parallel with the east coast almost to its southern tip. Nearly all the larger rivers, whose plains account for the bulk of the 22-25 per cent. of the total area which is suitable for culti? vation, flow westwards to the submerged coastline of the Yellow Sea. The latter abounds in natural harbours, though the best and most commodious anchorages are found along the southern coast, directly facing south-western Japan. The climate of Korea may be described as continental monsoon in type and its range is considerably greater than that of the main island of Japan (Honshu) with which it is almost identical in size and latitudinal extent. While in southern Korea summer temperatures are very similar to those in central Honshu though winters are colder, northern Korea, which adjoins the continental mainland and is exposed especially along the coast to fierce north-east winds, has much lower average temperatures and extremely bitter winters. Both in its effect on the relative agricultural productivity of the two halves, and in the strategic implications of the winter freeze which immobilizes the northern ports for up to three months in the year but nor? mally does not affect those of the south, this difference, which is merely one aspect of the deeper contrast between the maritime and continental halves of the country,* is all important. At the time when Korea first appears in reliable historical records shortly before the beginning of the Christian era, the cleavage between north and south was already evident in its political geography. For the north, forming,