During the reign of King Sonjo from 1576, when he passed the state examination for military service, through 1598, when he died in action in the Noryang Sea Battle during the Japanese invasion of Korea, he fought the alien invaders self-sacrificingly for the defense of his fatherland. His invention of the turtle ship enabled him to annihilate the invading Japanese armada off Hansando Island and Pusanpo Bay, thus helping him greatly in overcomeing the national crisis. All the people of Korea, who respect and admire him highly, erected Hyunchungsa Shrine in Asan, Chungchong-namdo Province, in memory of his noble spirit of loyalty and his sublime personality.