Yi Sun-sin

Career and command

Born in Seoul, Yi entered military service after passing examinations and held a series of posts before receiving naval command in the southwest. When war broke out in 1592, he emphasized training, readiness, and clear command structure. His leadership made effective use of local waters, tides, and narrow channels, while Korean ships carried strong artillery that could engage at a distance. These strengths allowed him to win important actions even when facing dangerous odds.

Yi is especially linked with the geobukseon, or turtle ship, an armored warship used alongside larger panokseon vessels. Later tradition made the turtle ship famous, but his victories were not based on a single weapon alone. Careful preparation, coordinated cannon fire, sturdy ship construction, and experienced crews were central to his success.

Major battles

His early victories included Okpo and Sacheon, and the Battle of Hansan Island in 1592 helped secure Korean control of key sea lanes. Court intrigue later led to his temporary dismissal, but he was restored to command after a disastrous defeat suffered by the fleet without him. In 1597, at the Battle of Myeongnyang, Yi used a narrow strait and shifting currents to defeat a far larger Japanese force, one of the most celebrated naval actions in Korean history.

• He kept detailed records that are valuable to historians.
• He was known for strict discipline and personal frugality.
• His naval campaigns helped protect communications and supplies for Korean and allied Ming forces.

Yi was killed in 1598 during the Battle of Noryang, near the end of the war. Tradition holds that he ordered his death to be concealed until the fighting had ended so that morale would not break. His diary, Nanjung Ilgi, and official reports remain important sources on the conflict. Over time he became a national hero in Korea, honored in statues, memorials, scholarship, and popular culture as a symbol of courage, competence, and steadfast public duty.