The Battle of Hansan-do, 1592

Admiral Yi Sun-shin Defeats the Japanese Invasion

Oar and sail-driven panokseon warship.
A Korean panokseon, or triple-decker warship. Used in the Imjin War against Japan, 1592-1598. Via Wikipedia, public domain due to age.

The year was 1592. After more than a century of bloody internal fighting, Japan had come through the Sengoku or "Warring States Period" and was united under the leadership of the warlord and commoner Toyotomi Hideyoshi.

Planning the Invasion

Hideyoshi needed an outlet for his warriors' energies. With peace at home, and thousands of battle-hardened samurai at his disposal, Hideyoshi turned his attention to thoughts of conquering Ming China, the region’s superpower.

The easiest way to conquer the Ming, he thought, would be to go through their tributary state, Joseon Korea. After Korea and China, Hideyoshi mused, perhaps he would take India...

Hideyoshi had every reason to suppose that his samurai could easily defeat the Joseon Koreans and the Ming Chinese. The Japanese troops had known only warfare, for all their lifetimes, and their fathers’ and grandfathers’ lifetimes as well.

Korea, on the other hand, had been at peace for centuries, and Korean energies were devoted to poetry, music, calligraphy, and other peaceful arts. One historian wrote (with some exaggeration) that “The story of Korean arms is a tragedy... It is the story of a people who repeatedly had to lay down their honored pen and brush to defend their lands and homes against those who loved the sword.” (J.L. Boots, 1934)

Hideyoshi had a healthy respect for the Ming Chinese, who possessed both immense numbers of troops and advanced military technology.

Nonetheless, he felt sure that his samurai could quickly overwhelm them before the unwieldy Chinese bureaucracy could respond. In addition, the Japanese had a new style of firearm, the arquebus musket, which they got from Dutch traders, then copied and improved.

The Samurai Invasion

Initially, everything went Japan’s way.

A force of 7,000 Japanese sailed to the port of Busan, on Korea’s southeast coast, on April 13, 1592, and sacked the city after a short siege. By June 10, this initial Japanese division had been joined by eight more, and they were knocking down the doors of King Seonjo’s palace in Seoul. (The king had already fled north to Pyongyang.) Thus began the seven-year-long Imjin War.

On July 24, 1592, the Japanese captured Pyongyang (now the capital of North Korea). Korea’s leadership fled still further north, to the Yalu River that marks the boundary between Korea and China. There, they sent urgent messages to the Ming court requesting military aid. China responded with a small force of 5,000, but one arm of the Japanese army penetrated as far north as the Jurchen area of Manchuria before the tide began to turn.

Admiral Yi to the Rescue

In its drive up the Korean Peninsula, the Japanese army depended upon its navy to supply it with food, ammunition and reinforcements. Korea faced the prospect of imminent extinction, and morale was very low. Admiral Yi Sun-sin, Naval Commander of the Left of Jeolla Province, decided to strike a decisive blow against Japanese naval shipping. He knew that he could not defeat the Japanese army single-handedly, but he could certainly hinder them.

On August 14, 1592, Admiral Yi set out to attack the Japanese fleet, commanded by Wakisaka Yasuharu, as it made its way along the southern coast of Korea near Geoje Island.

Wakizaka’s fleet of 73 ships included 13 small scouting ships called kobaya, 24 mid-sized seki bune, and 36 multi-decked atakebune. It was a formidable assemblage, but the Japanese ships carried few cannon. Japanese naval ships generally ran down their opponents, grappled and boarded them, rather than trying to demast or sink them with cannon-shot.

Admiral Yi had only 56 ships at his command, most the 70- to 100-foot triple-decked panokseon, which carried shields around their decks much like Viking longboats had done. Yi also had two or three of the now-famous “turtle ships.”

Many popular accounts of the battle actually credit Admiral Yi with the invention of the turtle ship, but the idea first appears in Korean sources as early as 1415.

The turtle ships were covered with overlapping spiked iron plates (hence the name), and featured a dragon-like head at the front. Sailors stoked fires below deck and funneled the smoke up through the dragon’s jaws, creating a terrifying spectacle. The ships were propelled both by fore-and-aft sails and by rows of oars on each side, making them more maneuverable than the Japanese square-sailed ships. They also carried cannon on both sides, a distinct advantage over the Japanese sailors’ muskets, bows and catapults.

The Battle of Hansan-do

Wakisaka’s fleet lay at anchor in the Gyeonnaeryang Strait between southern Korean and the large island of Geoje on the morning of August 14th. Admiral Yi ordered six of his panokseon to draw out the Japanese fleet from the channel; Wakisaka weighed anchor and sped out into open waters in pursuit.

When the panokseon and their pursuers reached the area near Hansan-do, the Japanese saw a fleet of nearly 50 additional Korean ships laying in wait. Admiral Yi deployed in the innovative “crane’s wing” formation, in which his fleet formed a boomerang shape that enveloped the Japanese ships, and peppered them with cannon-fire from both sides.

Wakisaka desperately tried to close with the Korean ships, but their shields and armor made grappling difficult. He sped his fleet ever closer into the center of the crane’s wing. The lightly-armed Japanese ships, though, were no match for the Korean fleet with its cannons.

Smoke poured out of the cannons, and the turtle ships' mouths. Flaming arrows, cannonballs, and musketballs filled the air. By mid-afternoon, 47 of the Japanese ships were at the bottom of the ocean, and an additional 12 had been captured by the Koreans. Approximately 8 - 9,000 Japanese sailors were killed. Admiral Yi lost not a single ship, and his casualties numbered only 19 killed and just over 100 injured.

Effects of the Battle of Hansan-do

The Imjin War dragged on for another six years after the Korean victory at Hansan-do, but Japan was no longer a serious threat to hold on to Korea, or capture China. The Japanese navy could not sail around the southern end of Korea into the Yellow Sea, so the land forces in what is now North Korea had no way to get food or reinforcements from the home islands. Humiliated by this defeat, Hideyoshi forbade his naval commanders from engaging in further naval battles against the Koreans.

Ming China finally put some of its strength into the war in January 1593, and contributed 100,000 soldiers to aid the newly revitalized Korean land forces. (The Koreans acted mostly as guerrilla fighters, while the Chinese did most of the set-piece fighting.)

Peace negotiations between Hideyoshi and the Ming government dragged on from the spring of 1593 through 1596. The Japanese daimyo withdrew most of his troops, but demanded a Chinese princess for a bride plus four of the provinces of southern Korea in return for becoming a vassal of the Ming Chinese. China refused these conditions, and Hideyoshi reinvaded early in 1597.

This time, the Koreans were much better prepared for the Japanese, both psychologically and militarily. Over 100,000 Japanese troops invaded at Busan again, but had trouble breaking out of the southeastern province of Gyeongsang-do.

Admiral Yi had been named Tongjesa, or commander of all the navies, after the Battle of Hansan-do.

However, Japanese agents and rival admirals conspired to ruin his reputation with King Seonjo. Seonjo demoted and imprisoned Yi in 1597.

In his place, the king put Admiral Won Gyun, who had none of Yi’s tactical brilliance, and had a drinking problem besides. Admiral Won lost the Battle of Chilchonryang (Japan’s only naval victory of the Imjin War) in spectacular fashion, and was killed by Japanese soldiers after he swam ashore from the wreckage of his flagship.

The king quickly pardoned and reinstated Admiral Yi, who found his once-mighty navy in tatters. Nonetheless, he managed to defeat a Japanese fleet of 300 ships with only 12 of his own, in the Battle of Myeongnyang. This glorious victory secured Admiral Yi’s place in Korean history.

On the 18th of September, 1598, Hideyoshi ordered the withdrawal of all Japanese forces from Korea. He died just hours later. The ruling council kept his death a secret, and waited more than a month before issuing the withdrawal decree.

In the meantime, one final naval battle at Noryang Point saw Japan lose almost half of the 500 ships it had anchored in the straits of Noryang. However, Korea suffered quite a loss in this battle, too; Admiral Yi caught a musket ball in his left side, and died on deck just prior to the Korean victory.

Significance of the Battle of Hansan-do, and the Imjin War

Although western history books tend to neglect this war, it had a profound effect on Japanese and Korean attitudes toward one another, and also on Chinese attitudes (to a lesser extent). Hideyoshi’s dream of an Asiatic empire lived on in Japan long after his death. In fact, Japan’s expansionist drive throughout the first half of the twentieth century followed essentially the same path as Hideyoshi’s sixteenth century plan of attack.

The Imjin War also witnessed the introduction and refinement of new military technologies, most famously, the turtle ships. Today, nearly every city in South Korea boasts a replica of one of Admiral Yi Sun-sin’s turtle boats. The admiral is widely revered in Korea; a tall statue of him stands watch over central Seoul, while another oversees the Busan Harbor from the tower hill.

Sources:

John King Fairbank and Denis Crispin Twitchett, The Cambridge History of China (Cambridge: Cambridge University Press, 1978).

Kim Ick-dal, Korea, Its People and Culture (Hakwon-sa Ltd., 1970).

Kenneth M. Swope, “Crouching Tigers, Secret Weapons: Military Technology Employed during the Sino-Japanese-Korean War, 1592-1598,” Journal of Military History 69, No. 1 (Jan., 2005), pp. 11-41.

Stephen Turnbull, Samurai Invasion: Japan’s Korean War, 1592-1598 (London: Cassell and Co., 2002).