?-1598

Korean admiral who built the first ironclad warships. In 1592, when the Japanese invaded Korea with the aim of conquering the peninsula and moving on to China, Yi ordered the building of 12 kobukson, or "tortoise ships." These lowdecked, armed galleys, covered with an iron-plated dome, faced a vastly larger Japanese force—133 ships—and won an overwhelming victory, sinking 31 vessels and routing the remainder. Despite this victory, however, the Koreans did not continue building ironclad warships, and the technique did not appear in the West until the nineteenth century.