Yi Sun-sin was appointed commander of the Left Jeolla (Jeolla-jwa) naval forces, a post from which he strengthened training, logistics, and shipbuilding (including development of the geobukseon “turtle ship”) in anticipation of war.
Toyotomi Japan launched the opening attacks of the Imjin War at Busan and nearby defenses, establishing a critical beachhead and port for the invasion of the Korean Peninsula.
Yi Sun-sin and allied forces struck Japanese ships anchored at Okpo, destroying numerous transports in what is commonly described as the first naval battle of the war and Yi’s first major victory at sea.
At Sacheon, Yi Sun-sin’s fleet defeated Japanese ships; sources describe this engagement as the first battle in which Yi deployed the turtle ship, reinforcing Joseon advantages in gunnery and ship protection.
Yi Sun-sin’s fleet defeated a Japanese force at Dangpo, sinking its ships and continuing a sequence of victories that disrupted Japanese coastal movements and supply efforts.
Yi Sun-sin defeated the Japanese fleet at Hansan Island, a major victory often credited with curbing Japanese naval operations and helping sever or endanger sea-based supply lines.
Shortly after Hansan, Yi Sun-sin engaged Japanese forces again at Angolpo, inflicting further ship losses and consolidating Joseon control in key southern waters.
Yi Sun-sin and allied commanders bombarded Japanese ships concentrated off Busan, destroying large numbers of vessels; however, the action did not eliminate the Japanese foothold at the port.
Court intrigue led to Yi Sun-sin’s arrest and removal from naval command; he was replaced by Wŏn Kyun, a command change that would soon coincide with catastrophic losses for the Joseon navy.
Under Wŏn Kyun, the Joseon navy suffered a near-total defeat at Chilcheollyang, losing most of its ships and key commanders—leaving only a small remnant force for subsequent defense.
Reinstated to command the surviving ships, Yi Sun-sin won a dramatic victory at the Myeongnyang Strait, using the narrow waters and currents to defeat a much larger Japanese fleet and restore strategic naval resistance.
In the war’s last major naval battle, Joseon and Ming forces attacked Japanese ships at Noryang Strait. The allies prevailed, but Yi Sun-sin was killed in action during the fighting.
Joseon Korea and Admiral Yi Sun-sin's naval campaigns (1592–1598)
