Korean History › Late Joseon › Imjin War (Japanese invasions of Korea)
Admiral Yi Sun-sin
1545–1598· Person· Wars & invasions
Well documentedSolid records, physical evidence or scientific consensus.
Joseon's naval commander in the Imjin War, who never lost a sea battle he commanded; Korea's foremost national hero.
See it on the Korean History map →What happened
Yi Sun-sin (이순신) passed the military exam late, in 1576. Named commander of the Left Jeolla Navy in 1591, he readied ships, including turtle ships, before the invasion. In 1592 he won a string of battles, including Hansan Island, closing Japan's sea route west. Court rivalry and a Japanese deception got him arrested and demoted in 1597; his successor Won Gyun then lost nearly the whole fleet at Chilcheollyang. Restored, Yi won at Myeongnyang with 13 ships and was killed at Noryang.
Why it matters
He kept Japan from supplying its armies by sea, a key reason the invasions failed. His statue stands in Seoul's Gwanghwamun Square.
Legacy and how we know
His own war diary (Nanjung ilgi), listed by UNESCO in 2013, and his battle reports to the court, checked against Ming and Japanese records.
Still debated
His exact battle tally varies by count; popular theories that he sought death at Noryang have no solid evidence.
Inside this (4)
Connections (4)
▸Admiral Yi Sun-sin used Turtle ship (geobukseon)Well documented
The connection
Yi Sun-sin and his officer Na Dae-yong revived an old idea, building turtle ships on panokseon hulls for the Jeolla Left Navy. Yi test-fired one's cannon the day before the invasion and used turtle ships as shock ships to break enemy lines at Sacheon, Hansan Island and other battles.
When and how
Built at Yeosu, the Jeolla Left Navy's base, in 1591–1592; first used at the Battle of Sacheon in July 1592.
How we know
Yi's diary records the cannon test on the eve of war, and his battle reports describe the ships in action.
Debates and open questions
How much of the design was Yi's, Na Dae-yong's, or a revival of the 1413 turtle ship is unclear.
▸Admiral Yi Sun-sin won Battle of Hansan IslandWell documented
The connection
Yi Sun-sin planned the trap: a few ships lured Wakisaka's fleet out of the narrow Gyeonnaeryang strait, then the main fleet wheeled into a crane-wing arc and fired broadsides. His choice of ground, formation and timing turned an even fight into a rout.
When and how
August 14, 1592, off Hansan Island near today's Tongyeong; Yi Sun-sin with Yi Eok-gi and Won Gyun against Wakisaka Yasuharu.
How we know
Yi's battle report to the court and Japanese records of Wakisaka's defeat.
Debates and open questions
How to share credit among Yi and the other Korean commanders, especially his rival Won Gyun, has been argued since the war.
▸Admiral Yi Sun-sin won Battle of MyeongnyangWell documented
The connection
Restored to command with a shattered navy, Yi Sun-sin rejected a court suggestion to give up the sea and fight on land. He picked Myeongnyang because its narrow width and fierce tides cancelled Japan's numbers, and he held the line in his own flagship until the current turned.
When and how
October 26, 1597, in the Myeongnyang strait off Jindo, South Jeolla; Yi's 13 ships against a fleet including Todo Takatora and Kurushima Michifusa.
How we know
Yi's diary entry for the day and his report to the court; Japanese records also note the defeat.
Debates and open questions
Why most of Yi's captains hung back at first, as his diary complains, and how much the tide alone decided the battle, are discussed.
▸Admiral Yi Sun-sin died winning Battle of NoryangWell documented
The connection
Yi Sun-sin insisted on attacking the retreating Japanese rather than letting them sail home, and persuaded the reluctant Ming admiral Chen Lin to join. In the pre-dawn battle a bullet struck him; he ordered his death hidden so the fighting would not falter, and his nephew kept the battle drums going.
When and how
Before dawn, December 16, 1598, in the Noryang strait between Namhae Island and the mainland; Yi Sun-sin and Chen Lin against Shimazu Yoshihiro.
How we know
The Sillok and the Jingbirok record his death and last words; Ming accounts confirm the joint battle.
Debates and open questions
Korean accounts say Konishi bribed Chen Lin to let a messenger boat slip out and summon Shimazu; how far Chen Lin was complicit is debated.