Iron Spikes And A Dragon's Head: Yi Sun-sin's Turtle Ship

The Japanese invasion of Korea in the late 16th Century met its fiercest resistance in the sea, where the Korean hero Admiral Yi Sun-sin proved unbeatable. Today, South Korea’s veneration for Yi is demonstrated in his prevalence across multiple series of South Korean notes.

On the eve of his greatest victory at the Battle of Myeongyang, Admiral Yi Sun-sin attempted to rally the commanders of the Korean Joseon Navy in the face of overwhelming odds.

"He who seeks his death shall live," he said. "He who seeks his life shall die."

By day's end on October 26, 1597, Yi's forces had destroyed 31 of 130 enemy Japanese ships and sent all those remaining into full retreat in one of the unlikeliest victories in the history of naval warfare. Yi started and ended the battle with just 13 ships of his own.

Yi was undefeated in naval combat. In his honor, a memorial and museum stand at the sites of each of his 23 victories. He is credited with creating the turtle ship, or kobukson, a revolutionary iron-reinforced warship that dominated invading Japanese fleets in the late 16th Century. The 2014 South Korean blockbuster The Admiral: Roaring Currents, a dramatization of the events at Myeongyang, holds Korean box office records for admissions and total gross. Yi and his turtle ship are featured on 7 varieties of South Korean banknotes.

Yi Sun-sin's legend continues to thrive more than four-hundred years after his death. Surely, he took his own words to heart.

Yi Sun-sin was born on April 28, 1545 in Seoul, Korea (now in South Korea). He became a military officer in 1576 and briefly served in the navy in 1580 before returning to the army.

In 1587 he fell victim to a political rivalry and was demoted to a common soldier, but childhood friend and future Korean Prime Minister Yu Songnyong helped Yi regain his status. He became the Left Naval Commander of Cholla Province in 1591.

South Korea P-43, front

Yi’s new position allowed him to oversee preparations for an impending Japanese invasion of the Korean Peninsula. Engineers under his command constructed the turtle ship, an ore-and-sail warship with an iron skeleton, which accompanies Yi’s vignette on the face of South Korea P-43.

Replica of Yi Sun-sin's Turtle Ship

The turtle ship’s iron framework could support stronger cannon than Japanese craft, as Korean gun crews could fire without risking the ship’s structural integrity. Iron spikes lined the top “shell” to ward against boarding—a favorite tactic of the Japanese navy. The dragon’s head on the front of the craft could bear additional cannon and fire throwers. This additional payload supplemented the ship’s limited space below deck, as evidenced in the scale replica that occupies the first floor of the War Memorial of Korea in Seoul.

The turtle ship made its first appearance in the Battle of Sach’on on July 8, 1592. The Koreans revealed it in a surprise attack after luring the Japanese fleet in a faked retreat. Yi selected a brave captain to command the vessel, who led it on a devastating counterattack in which Korean forces sank every enemy Japanese ship pitted against them.

South Korea P-15

A more classical representation of the turtle ship adds some flair to the kinetic South Korea P-15. In addition to cannonballs and flame, engineers could also rig the dragon’s head to emit a smokescreen that masked the ship’s position. Furthermore, this minimalist portrayal of the gun ports highlights another security feature that Yi described in a 1592 report to the Korean King Sonjo, which said “Our men can look out from inside, but the enemy cannot look in from outside.”

The turtle ship was misnamed in terms of its speed. With up to 20 ores, a sail, and its oval shape providing cannon fire from any direction, it could assume its lead position with ease and chase down most models of Japanese craft attempting to retreat.

During the Battle of Hansando on August 14, 1592, Yi sprang a trap on an aggressive Japanese fleet using the crane’s wing formation: a u-shaped grouping of panokson, the standard Joseon Navy wooden battleships, which were anchored on both ends by turtle ships for protection. The crane’s wing formation achieved a balance of minimal casualties while ensuring maximum damage to enemies through establishing cannon crossfire.

In this case, Yi used his turtle ships offensively and ordered them to speed straight into the Japanese vanguard. Through a combination of ramming and unleashing broadsides at close range, the turtle ships decimated Japan’s front line and broke their formation. Panokson crews initially supported with cannon fire from afar, but went in to board any crippled Japanese vessels at Yi’s discretion. The Japanese fleet was almost entirely destroyed.

South Korea P-39, back

South Korea P-39’s reverse depicts a strafing maneuver of the panokson, the three rear ships on the note, spearheaded by two turtle ships. This brings to life one of many strategies Yi employed to overcome numbers disadvantages in the majority of his battles.

Admiral Yi Sun-sin died on December 16, 1598 at the height of the Battle of Noryang—the last sea battle of the failed Japanese invasions of Korea. His final orders to his nephew and eldest son, the only soldiers who witnessed him get hit in the left shoulder by a Japanese sharpshooter, were to keep his death a secret from the other men in order to maintain morale. His son and nephew hid his body under a shield and waited until the fight ended to allow the news to spread.

South Korea P-23, back

The reverse of South Korea P-23 (the Pick number a rather providential match to his victory count as an admiral) shows a regal statue of Yi flanked by another portrait of his turtle ship. According to military historian Stephen Turnbull, Yi’s statue “seems to be everywhere” in South Korea, especially throughout the southern island chains so near his many battlefields.

South Korea P-43, back

The Hyeonchungsa Shrine, built in 1706 in Asan-si, South Korea, decorates the reverse of South Korea P-43 and is referred to by the Official Korean Tourism Organization as a “sacred place.” Yi’s Nanjung Ilgi (his meticulously-kept war diary) and his sword are both displayed here and are designated national treasures.

Admiral Yi Sun-sin’s success at sea prevented Japan from reinforcing its troops on the Korean peninsula, which forced an early end to the seven-year war that had already tallied more than 185,000 Korean deaths. The last Japanese ships departed in December of 1598. Yi’s victories had assured Korea’s sovereignty and increased the nation’s standing in the eyes of their Chinese allies.

But 300 years later, even the Japanese continued to respect Yi’s tactical prowess. Admiral Togo Heihachiro, victor of the Battle of Tsushima in the Russo-Japanese War in 1905, didn’t refute claims comparing him to the British Royal Navy hero Horatio Nelson; his response to a comparison with Yi Sun-sin, however, was more definitive.

“He is too great to be compared to anyone.”

Sources:

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