㉞ The History of the Turtle Ship (Geobukseon) Through the Records

I have already written six posts about the turtle ship on this blog: the series "Why Did the Turtle Ship Fight for Only Three Months?" That series was about how the turtle ship was used in battle.

👉 ⑮ Why Did the Turtle Ship Fight for Only Three Months? (Part 1)

In this post, I will follow the old records of the turtle ship (geobukseon), the armored assault ship that Admiral Yi Sun-sin — the commander who saved Joseon at sea during the Imjin War — sent into battle against the Japanese.

The name "turtle ship" first appears in 1413 and continues until 1886. That is more than 470 years. I will set down that long span of time in order.

A Turtle Ship Seen 180 Years Before Admiral Yi

The Turtle Ship King Taejong Saw

The first record in which the name "turtle ship" appears is the Annals of King Taejong.

"As the king passed Imjindo (臨津渡), he watched a turtle ship [龜船] and a Japanese ship (倭船) fight each other." (Annals of King Taejong, Vol. 25, 5th day of the 2nd month, 13th year of Taejong)

This was 1413. At a ferry crossing on the Imjin River, a mock battle was held between a turtle ship and a ship dressed up as a Japanese vessel. The king watched it.

Two years later, Tak Sin, a royal secretary (jwadaeeon), submitted his opinion.

"The method of the turtle ship [龜船] is such that even when it collides with many enemies, the enemy cannot harm it; it may truly be called a fine plan for winning a decisive victory. I ask that it be built again, sturdy and skillfully made, so that we may be equipped with a tool for victory in battle." (Annals of King Taejong, Vol. 30, 16th day of the 7th month, 15th year of Taejong)

It was a ship that took no harm even when it rammed the enemy. It appears to have been an assault ship built to fight off the waegu, the Japanese pirates. For this reason, some see the roots of the turtle ship in the late Goryeo period, when the Japanese pirates were at their worst. But there is no record of what the turtle ship of Taejong's time looked like. Only the name remains. After that, the turtle ship disappears from the records for a long time.

1592: Back on the Sea

Preparations Left in the Diary

In the 2nd month of 1591, Admiral Yi became Left Jeolla Naval Commander and took up his post at Yeosu. And in the spring of the following year, the turtle ship appears in his diary, the Nanjung Ilgi.

"On this day I received twenty-nine bolts of sailcloth for the turtle ship." (Nanjung Ilgi, 8th day of the 2nd month, imjin year [1592])

"At the same time, I also tested the firing of cannons from the turtle ship." (Nanjung Ilgi, 27th day of the 3rd month, imjin year)

"For the first time, sails were made from cloth." (Nanjung Ilgi, 11th day of the 4th month, imjin year)

"After the meal, I boarded the ship and fired the jija and hyeonja cannons of the turtle ship. Nam Han, an officer of the Provincial Inspector, watched and left." (Nanjung Ilgi, 12th day of the 4th month, imjin year)

On the 12th day of the 4th month, he test-fired the turtle ship's cannons. The next day, the 13th day of the 4th month, the Japanese army appeared off Busan. It was one day's difference.

It is said that the officer Na Dae-yong played a large part in building this ship.

👉 ④ The Turtle Ship's Shipbuilding Supervisor: Na Dae-yong

The Turtle Ship in the Admiral's Own Words

There is only one piece of writing in which the Admiral himself described the turtle ship: his report to the throne on the Battle of Sacheon.

"Anticipating trouble from the island barbarians, I had earlier built a turtle ship separately. At the front a dragon's head is attached, and cannons are fired through its mouth; iron spikes are planted on its back; and from inside one can see out, but from outside no one can see in. So even in the midst of several hundred enemy ships, it can easily charge in and fire its cannons." (Yi Chungmugong Jeonseo, Vol. 2, "Report on Destroying the Japanese Forces at Dangpo")

The Admiral made four things clear. It had a dragon's head, and cannons were fired through its mouth. Its back had iron spikes. From inside one could see out, but from outside one could not see in. And so it could charge into the very middle of the enemy ships.

The Turtle Ship His Nephew Left Us

A somewhat more detailed record is found in the Haengnok, the account of the Admiral's life written by his nephew Yi Bun.

"He also created a warship. It was about the size of a panokseon and covered on top with planks. On the planks a narrow cross-shaped (+) path was made so that people could walk across the top, and all the rest was studded with knives and awls so that there was no place to set foot anywhere. At the front a dragon's head was made and attached, its mouth serving as a gun port, and the stern was shaped like a turtle's tail, with a gun port beneath the tail as well; on the left and right there were six gun ports each. Because its shape as a whole was like that of a turtle, it was called the turtle ship." (Yi Chungmugong Jeonseo, Vol. 9, Haengnok)

It was the size of a panokseon, the standard Joseon warship of the time. It was a panokseon covered on top with planks. There was one gun port in the dragon's head, one beneath the tail, and six on each side: fourteen in all.

The Haengnok also describes how it looked in battle. The knives and awls were covered with straw mats, and it went out at the very front. When the enemy leapt aboard, they were pierced by the blades. When the enemy surrounded it, it fired from front, back, left, and right all at once.

The Turtle Ship the Enemy Saw

There is also a record on the Japanese side: the Koraisen Senki (高麗船戰記, "Record of the Battles with the Korean Ships"). It was written at Busanpo in the 7th month of 1592 by Sotooka Jinzaemon, who served with the Japanese navy. He wrote it after seeing the Battle of Angolpo with his own eyes.

"Three of the large ships were 'blind ships' (盲船: the Japanese nickname for the turtle ship), fortified with iron (鐵), and they took turns charging in and firing ishibiya (石火矢), bōbiya (棒火矢), ōkarimata (大狩俣) arrows and the like until the hour of the rooster (about 6 p.m.), so that everything from the upper deck to the passageways and the shields below the rails was completely smashed." (quoted from the Koraisen Senki)

The Japanese called the turtle ship a "blind ship." This was probably because no one could see inside it. It is exactly the ship the Admiral described when he wrote that "from outside no one can see in."

How Many Ships, and How Many Men Aboard

In 1595, Joseon reported the state of its navy to Ming China.

"Naval Commander Yi Sun-sin … leads 60 warships, 5 turtle ships, and 65 scout boats (哨探船) …" (Sadae Mungwe, Vol. 12, quoted in the appendix to The Diary of Yi Sun-sin)

In 1595, there were five.

How many men were aboard can be estimated from a memorial submitted by Na Dae-yong after the war. He said that the archers and oarsmen of a turtle ship were no fewer than the 125 of a panokseon. I estimate the number at about 130.

Was It an Ironclad?

What the Records Say

The turtle ship is often called the world's first ironclad.

But the Admiral's report says nothing about iron armor. It says only that "iron spikes are planted." The Haengnok, too, says it was "covered with planks." Iron armor does not appear in the description of the turtle ship in the Yi Chungmugong Jeonseo, published in 1795, either.

Two records are cited as evidence of iron armor.

One is the phrase "fortified with iron (鐵)" in the Koraisen Senki, which we saw above. It is read as meaning that the ship was firmly protected with iron.

The other is a 1748 report to the throne by the Left Gyeongsang Naval Commander. It describes the turtle ship like this:

"The so-called turtle ship has no deck tower; it is covered with planks, and on top of them scale armor is layered again." (report to the throne by the Left Gyeongsang Naval Commander, "Record of the Scale Armor" [鱗甲記錄], quoted in the appendix to The Diary of Yi Sun-sin)

Ingap (鱗甲) means armor joined together like scales. This is the first time iron armor on the turtle ship appears in our own records. But it is a record from 150 years after the Admiral's death.

The Turtle Ship After the Admiral

Lost at Chilcheollyang, Then Rebuilt

In the 7th month of 1597, the Joseon navy collapsed at Chilcheollyang. It is said that all the turtle ships were lost then as well. There were no turtle ships at Myeongnyang, nor at Noryang.

In 1606, Yi Un-ryong, Naval Commander of the Three Provinces, forwarded a memorial from Na Dae-yong to the court. It contains this passage:

"The turtle ship [龜船] is good for use in war, but it must carry no fewer archers (射手) and oarsmen (格軍) than the 125 of a panokseon (板屋船), and it is also inconvenient for shooting arrows; therefore only one is stationed at each naval command, and no more are being built." (Annals of King Seonjo, Vol. 206, 24th day of the 12th month, 39th year of Seonjo)

This was eight years after the war ended. By then, each naval command already had one turtle ship.

In 1622, King Gwanghaegun gave this order:

"Tell them specially to quickly build Sun-sin's turtle ships, repair their weapons, and train their soldiers, so as to prepare faithfully for any emergency, doing everything just as Sun-sin did." (Diary of Gwanghaegun, Vol. 179, 22nd day of the 7th month, 14th year of Gwanghae)

After the seven-year Imjin War had ended, the order to build turtle ships again came from the king's own mouth. Gwanghaegun, the reigning king, clearly said, "just as Sun-sin did," but this order was not kept.

No One Knew the Dimensions

The problem was the original form.

In 1615, Inspector Gwon Ban set the dimensions of warships according to the Admiral's old system. At that time, officers and old soldiers who had served under the Admiral were still alive. But when the court looked at this document again seventy years later, the dimensions of the turtle ship were missing.

"Since the system and measurements of the turtle ship are not included in the Inspector's regulations, the claim that it will gradually grow taller and larger, just like the warships, seems indeed to be so." (Bibyeonsa Deungnok, 1st day of the 1st month, 13th year of Sukjong)

Here, "measurements" (jasu) appears to refer to the dimensions of the ship.

While the people who knew the Admiral's turtle ship exactly were still alive, no one wrote down its dimensions.

Bigger and Heavier

After that, the turtle ship grew steadily larger. In 1751, Bak Mun-su, the tax commissioner for Yeongnam, reported to the king:

"I have looked at what Chungmugong (忠武公) Yi Sun-sin (李舜臣) recorded: he made six gun ports on each side of the turtle ship, but now eight ports are made on each side. From this, too, one can see that the turtle ship has grown excessively large compared with before, so it cannot but be remodeled." (Annals of King Yeongjo, Vol. 73, 21st day of the 2nd month, 27th year of Yeongjo)

The crew grew too. A record from 1704 gives the complement of one turtle ship as 148 men (Annals of King Sukjong, Vol. 40, 28th day of the 12th month, 30th year of Sukjong). That is about twenty more than on Admiral Yi's turtle ship.

A Turtle Ship in Name Only

By the 19th century, there were even words like these, spoken by Kim Jae-chan, Chief State Councillor under King Sunjo:

"From what I have heard recently, the turtle ships at each naval command are called turtle ships in name, but it is a case of hwaho bulseong (畵虎不成); they are no different from other ships." (Ilseongnok, 17th day of the 4th month, 9th year of Sunjo, quoted in the appendix to The Diary of Yi Sun-sin)

Hwaho bulseong means "trying to draw a tiger and failing." It means they were turtle ships in name only and no different from other ships.

And yet their number actually grew. In 1606 and 1716 there were five. The Sok Daejeon of 1746 lists fourteen, and the Mangi Yoram of 1808 lists thirty (as summarized in the appendix to The Diary of Yi Sun-sin). There were more of them, but perhaps it was only a count of ships that, as hwaho bulseong suggests, had merely been given the name "turtle ship."

1795: The Turtle Ship of the Yi Chungmugong Jeonseo

The Turtle Ship Pictures We Know

Most of the turtle ship pictures we saw in our textbooks come from the Yi Chungmugong Jeonseo, the collected works of Admiral Yi, published in 1795 by order of King Jeongjo. At the front of the book are two pictures of turtle ships: the "Turtle Ship of the Unified Naval Command" (Tongjeyeong Gwiseon) and the "Turtle Ship of the Left Jeolla Naval Command" (Jeolla Jwasuyeong Gwiseon).

The descriptions are detailed too. They say the length of the bottom planking was 64 cheok 8 chon (about 19.9 m). They also record what came out of the dragon's head.

"Inside it, sulfur and saltpeter are burned, and smoke is breathed out like fog through the open mouth to confuse the enemy." (Yi Chungmugong Jeonseo, front volume, "Illustrated Explanation of the Turtle Ship" [龜船圖說], quoted in the appendix to The Diary of Yi Sun-sin)

The Admiral's turtle ship fired cannons through the dragon's mouth. The turtle ship two hundred years later breathed smoke through the dragon's mouth.

Turtle Ship of the Left Jeolla Naval Command (Yi Chungmugong Jeonseo)

The number of gun ports was different, too. The commentary in the appendix to The Diary of Yi Sun-sin counts 74 on the Unified Naval Command turtle ship and 36 on the Left Jeolla Naval Command turtle ship. Admiral Yi's turtle ship had 14 in all. And I cannot help but point out something about the turtle ship's head. The Admiral clearly wrote in his report: "At the front a dragon's head is attached, and cannons are fired through its mouth." Yet in the Yi Chungmugong Jeonseo, two hundred years later, the turtle ship's head has a long neck, which makes firing a cannon through it look impossible. I maintain that the turtle ship had no neck and that only a dragon's head was attached at the front.

The Compilers' Confession

The compilers of this book were honest. After transcribing the Haengnok and the record of Hua Yu of Ming China, they wrote:

"Yet none of them, taken together, speaks in detail of its dimensions. The turtle ship of the present Unified Naval Command mostly derives from Chungmugong's old system, but it is not without some additions and subtractions in its measurements." (Yi Chungmugong Jeonseo, front volume, "Illustrated Explanation of the Turtle Ship," compilers' note, quoted in the appendix to The Diary of Yi Sun-sin)

They stated plainly that the dimensions of the Admiral's turtle ship could not be known. So these pictures show the turtle ship of 1795. They do not show the turtle ship of 1592.

The full-size restored turtle ship first launched at the Jinhae naval base in 1979 was also modeled on these pictures, mainly the turtle ship of the Left Jeolla Naval Command. Iron armor and iron spikes were added to it, to present it in a form commemorating the Admiral's turtle ship.

The Size of the Restored Turtle Ship

The appendix to The Diary of Yi Sun-sin includes a cross-section and the dimensions of this restored turtle ship (Korea Naval Academy, 1979). They are given in cheok (尺), so I have converted them to meters. I counted one cheok as about 30.65 cm, following the yeongjocheok, the carpenter's foot of late Joseon.

Item	Recorded value	In meters
Overall length	113 cheok	about 34.6 m
Hull length	84 cheok	about 25.7 m
Beam (width of the ship)	34 cheok	about 10.4 m
Hull height	21 cheok	about 6.4 m
Draft (depth below the waterline)	4.5 cheok	about 1.4 m
Displacement	150 tons	—
Crew	130	—
Speed	about 7 knots	about 13 km/h

The overall length of 113 cheok matches the 113 cheok that the "Illustrated Explanation of the Turtle Ship" gives as the length of the topmost board of the side planking. The restoration appears to have followed the dimensions in the "Illustrated Explanation." So these dimensions, too, are based on the turtle ship of 1795. They are not the dimensions of Admiral Yi's turtle ship. I set them down here for my readers' reference.

👉 ㉘ Comparing the Warships of Joseon, Ming, and Japan in the Imjin War

The Last Records

In 1808, King Sunjo asked Yi Dang, a former Naval Commander:

"Are there turtle ships, or not?" … "There are. … Because smoke comes out of their mouths and noses, even now, when Japanese who have drifted ashore (漂流) see them, they are startled and say to one another, 'This is a machine for capturing people.'" (Annals of King Sunjo, Vol. 11, 10th day of the 1st month, 8th year of Sunjo)

A time had come when the king had to ask whether there were any turtle ships at all.

The last record of the turtle ship in the sources I used this time is from 1886. In a report by Yi Yong-gwan, a former Right Jeolla Naval Commander, on the organization of the naval garrisons, there is this phrase:

"The units of the two turtle ship commanders (龜船將) of Naju are in good order and are all ready to go out for drill." (Annals of King Gojong, Vol. 23, 20th day of the 4th month, 23rd year of Gojong)

The name that began in 1413 at a ferry crossing on the Imjin River ends in 1886 at Naju. Not long after, Joseon's naval system itself came to an end.

The Ship Remained, the Man Did Not

Following the turtle ship through 470 years, I lingered long over one sentence, the words of King Gwanghaegun:

"Doing everything just as Sun-sin did."

The court could build turtle ships again. It could increase their number. It could make them bigger and fit them with more cannons. But no one knows whether they were the same turtle ship that Admiral Yi built, because neither the dimensions nor the plans of the turtle ship survived. That is the reality in which Gwanghaegun's words sound so painfully sad.

"Doing everything just as Sun-sin did."

👉 Next post: ㉟ The Heart That Beheads and the Heart That Gives Away Its Clothes: Admiral Yi Sun-sin

— Momcheolhak