Yi Sun-Sin was born in April 1545 AD and destined to be Korea’s greatest (actually, only) naval hero. After passing examinations, he entered into military service to the Joseon dynasty in 1576. Although discharged a couple of times for misconduct, in 1591 he was appointed commander of the naval forces in the port of Yeosu; there he concentrated on training recruits, stockpiling munitions, and designing the kobukson (“turtle ship”). The kobukson was the first ironclad in civilization, its upper deck covered in armored plates, armed with cannons, with smoke pots to obscure the ship. Just in time for the Japanese invasions that commenced in 1592.
In four brilliant operations over the course of that year, Yi Sun-Sin’s forces – spearheaded by turtle ships – won fifteen battles and sank hundreds of the flimsy Japanese ships. In recognition, Yi was given command of the combined naval forces of three southern provinces – Jeolla, Gyeongsang and Chungcheong. But following peace negotiations, he was again accused of disloyalty and thus demoted to the rank of common sailor. But when the Japanese launched a second invasion and quickly destroyed most of the Korean fleet, he was promptly restored to his command.
Things looked dire for Korea as the Japanese landed, supported by a massive combined fleet of some 300 ships (at least 133 of these warships). Yi managed to gather 13 Korean ships – a mix of panokseon and kobukson – and maneuvered such as to lead the overconfident Japanese into a narrow strait. In the ensuing battle of Myeongnyang in October 1597, the Japanese lost 31 ships (and the commanding Japanese admiral was killed aboard his flagship) while Yi suffered only 13 casualties. But a year later, in December 1598 after Yi Sun-Sin had defeated yet another massive Japanese fleet, he was killed by a bullet during the pursuit.