The Turtle ship was a Korean warship of radical and innovative design, and was used from the early 15th century to the 19th century, during the Joseon Dynasty.
The first references to older, first generation turtle ships come from 1413 and 1415 records in the Annals of the Joseon Dynasty. These turtle ships were mentioned as "spear-ships" or "ramming ships" and were mainly used against Japanese pirates and invasion forces in Korean coastal areas. These early turtle ships soon fell out of use, though, because of a long period of relative peace and almost no maritime military operations.
Turtle ships are famous for participating in numerous victories against Japanese naval forces that supported Toyotomi Hideyoshi's attempts to conquer Korea from 1592-1598, inflicting heavy losses. Korean admiral Yi Sun-sin is credited with designing and building the craft known today. His turtle ships were equipped with at least five different types of cannon. The turtle ship's most distinguishable feature was a fully covered deck that was shielded to deflect cannon fire with iron spikes to discourage enemy men from attempting to board the ship. It is also considered by most to be the first iron-clad ship in the world. Admiral Yi Sun-sin initially had five turtle ships built. By 1782, there were at least 40 turtle ships commissioned.
According to the Nanjung Ilgi, Yi's wartime diary, Yi decided to resurrect the turtle ship in 1591, from pre-existing designs, after discussing the matter with his subordinates, expecting a possible foreign invasion. Yi and his subordinate officers constructed the first modern turtle ship. Yi's diary, along with the book entitled Hangrok, by his nephew Yi Beon, described numerous important details about the structures, construction progress, and the use of turtle ships in battle, as well as the testing of weaponry used in the ships.
The mounted weapons, Korean Cannon with ranges from about 300 to 500 meters, were tested on March 12, 1592. Yi completed the first turtle ship and launched it on March 27, 1592, one day before the Siege of Busan and the Battle of Tadaejin.
On the bow of the vessel was mounted a dragon head which emitted sulfur smoke to effectively hide its movement from the enemy in short distance combat. The dragon head was large enough for a cannon to fit inside. The dragon head served as a form of psychological warfare, striking fear into the hearts of Japanese sailors. Early versions of the turtle ship would burn poisonous materials in the dragons head to release a poisonous smoke.
In the front of the ship was a large anchor. Below the anchor was a wooden crest that was shaped like a face, and these were used to ram into enemy ships. Similar to the standard Panokseon, the turtle ship had two masts and two sails. Oars were also used for maneuvering and increased speed. Another advantage the turtle ship had over its enemies, was that the turtle ship could turn on its own radius.
The turtle ship had 10 oars and 11 cannon portholes on each side. Usually, there was one cannon porthole in the dragon head's mouth. There were two more cannon portholes on the front and back of the turtle ship. The heavy cannons enabled the turtle ships to unleash a mass volley of cannonballs (some would use special wooden bolts several feet in length, with specially engineered iron fins). Its crew complement usually comprised about 50 to 60 fighting marines and 70 oarsmen, as well as the captain.
Sources indicate that sharp iron spikes protruded from hexagonal plates covering the top of the turtle ship. An advantage of the closed deck was that it protected the Korean sailors and marines from small arms and incendiary fire. The spikes discouraged Japanese sailors from engaging in their primary method of naval combat at the time, grappling an enemy ship with hooks and then boarding it to engage in hand to hand combat.
Korean written descriptions all point to a maneuverable ship, capable of sudden bursts of speed. Like the standard Panokseon, the turtle ship featured a U-shaped hull which gave it the advantage of a more stable cannon-firing platform, and the ability to turn within its own radius. The main disadvantage of a U-shaped bottom versus a V-shaped bottom was a somewhat slower cruising speed.
In a painting found in a Japanese castle, the turtle ships are depicted as three-decked mammoths, large enough in size to be compared to a modern ship. Cannons were positioned on the third deck, archers on the second deck, and troops on the first deck.
Contemporary Korean records
Contemporary Japanese records
It should be noted that the iron-plating of the turtle ship was motivated by very different fighting techniques than that of the 19th century ironclad. While the ironclad featured armour covering the sides, and later also all around, in order to protect the vessel from enemy shells, the iron roof of the turtle ship was meant to prevent the Japanese soldiers from boarding.
Yi's own diary explains that a cannon could be fitted in the mouth of the dragon to be fired at enemy ships.
The turtle ship was equipped with Cheonja (Heaven), Ghija (Earth), Hyunja (Black), and Hwangja (yellow) type cannons. There was also an arquebus known as Seunja (victory). The Seungja cannon ranged 200 meters, while the Cheonja was the heaviest with a range of 600 meters. The Hyunja and Hwangja cannons were medium-sized cannons that usually shot large fire arrows instead of cannonballs. One Japanese record of the Battle at Angolpo records the experience of two Japanese commanders on July 9th, 1592 in their of battle against turtle ships, "their(turtle ship's) attack continued until about 6 o'clock in the afternoon, by firing large fire-arrows through repeated alternate approaches, even as close as 18-30 feet. As a result almost every part of our ships - the turret, the passages and the side shielding - were totally destroyed..."
The turtle ship's main use of the plating was as an anti-boarding device, due to the top plating of the turtle ship and its protruded spikes. Grappling hooks could not gain direct hold on the plating, and jumping to the turtle ship often meant being impaled. The iron plating also made it more difficult for Japanese ships to destroy, because it allowed the turtle ship to survive enemy mortar-fire, as well as deflecting arquebus rounds and arrows.
Later, the turtle ship was used for other purposes such as spearheading attacks or ambushing Japanese ships in tight areas such as in the Battle of Noryang.
Despite popular depiction, the turtle ship was not an extremely slow ship. The turtle ship had oar propulsion as well as sails, and was relatively lightweight due to its very limited plating. Admiral Yi constructed the turtle ship to be fast and agile for the purpose of ramming.
Turtle ships and Admiral Yi Sun-shin can be played in the computer game Age of Empires II: The Conquerors in a one-episode campaign against the invasion of the Japanese navy.
In Pirates Constructible Strategy Game there are a great number of turtle ships.
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