The Imjin War, 1592-98

Ming Army in Korea during Imjin War
The Ming Army in Korea during the Imjin War. via Wikipedia

Dates: May 23, 1592 - December 24, 1598

Adversaries: Japan versus Joseon Korea and Ming China

Troop strength: 

Korea - 172,000 national army and navy, 20,000+ insurgent fighters

Ming China - 43,000 imperial troops (1592 deployment); 75,000 to 90,000 (1597 deployment)

Japan - 158,000 samurai and sailors (1592 invasion); 141,000 samurai and sailors (1597 invasion)

Outcome: Victory for Korea and China, led by Korean naval successes. Defeat for Japan.

In 1592, the Japanese warlord Toyotomi Hideyoshi launched his samurai armies against the Korean Peninsula. It was the opening move in the Imjin War (1592-98). Hideyoshi envisioned this as the first step in a campaign to conquer Ming China; he expected to roll over Korea quickly, and even dreamed of going on to India once China had fallen. However, the invasion did not go as Hideyoshi planned.

Build-up to the First Invasion


As early as 1577, Toyotomi Hideyoshi wrote in a letter that he had dreams of conquering China. At the time, he was just one of Oda Nobunaga's generals. Japan itself was still in the throes of the Sengoku or "Warring States" period, a century-long era of chaos and civil war among the different domains.

By 1591, Nobunaga was dead and Hideyoshi was in charge of a much more unified Japan, with northern Honshu the last major region to fall to his armies. Having accomplished so much, Hideyoshi began to give serious thought once more to his old dream of taking on China, the major power of East Asia. A victory would prove the might of reunified Japan, and bring her immense glory.

Hideyoshi first sent emissaries to the court of Joseon Korea's King Seonjo in 1591, requesting permission to send a Japanese army through Korea on its way to attack China. The Korean king refused. Korea had long been a tributary state of Ming China, while relations with Sengoku Japan had seriously deteriorated thanks to incessant Japanese pirate attacks all along Korea's coast. There was simply no way that the Koreans would allow Japanese troops to use their country as a staging ground for an assault on China.

King Seonjo sent his own embassies to Japan in turn, to try and learn what Hideyoshi's intentions were. The different ambassadors returned with different reports, and Seonjo chose to believe those who said that Japan would not attack. He made no military preparations.

Hideyoshi, however, was busy gathering an army of 225,000 men. Its officers and most of the troops were samurai, both mounted and foot soldiers, under the leadership of some major daimyo from Japan's most powerful domains. Some of the troops were also from the common classes, farmers or craftsmen, who were conscripted to fight.

In addition, Japanese workers built a huge naval base on western Kyushu, just across the Tsushima Strait from Korea. The naval force that would ferry this enormous army across the strait consisted of both men-of-war and requisitioned pirate boats, manned by a total of 9,000 sailors.

Japan Attacks

The first wave of Japanese troops arrived at Busan, on Korea's southeast corner, on April 13, 1592. Some 700 boats offloaded three divisions of samurai soldiers, who rushed Busan's unprepared defenses and captured this major port in a matter of hours. The few Korean soldiers who survived the onslaught sent messengers running to King Seonjo's court in Seoul, while the rest retreated inland to try to regroup.

Armed with muskets, against Koreans with bows and swords, the Japanese troops quickly swept toward Seoul. About 100 kilometers from their target, they met the first real resistance on April 28 - a Korean army of about 100,000 men at Chungju. Not trusting his green recruits to stay on the field, Korean general Shin Rip staged his forces in a swampy y-shaped area between the Han and Talcheon Rivers. The Koreans had to stand and fight or die. Unfortunately for them, the 8,000 Korean cavalry riders bogged down in flooded rice paddies and Korean arrows had a much shorter range than the Japanese muskets.

The Battle of Chungju soon turned into a massacre. General Shin led two charges against the Japanese, but couldn't break through their lines. Panicking, the Korean troops fled and jumped into the rivers where they drowned, or got hacked down and decapitated by samurai swords. General Shin and the other officers committed suicide by drowning themselves in the Han River.

When King Seonjo heard that his army was destroyed, and the hero of the Jurchen Wars, General Shin Rip, was dead, he packed up his court and fled north. Angry that their king was deserting them, people along his flight path stole all of the horses from the royal party. Seonjo didn't stop until he reached Uiju, on the Yalu River, which is now the border between North Korea and China. Just three weeks after they landed at Busan, the Japanese captured the Korean capital of Seoul (then called Hanseong). It was a grim moment for Korea.

Admiral Yi and the Turtle Ship

Unlike King Seonjo and the army commanders, the admiral who was in charge of defending Korea's southwest coast had taken the threat of a Japanese invasion seriously, and had begun to prepare for it.  Admiral Yi Sun-shin, the Left Navy Commander of Cholla Province, had spent the previous couple of years building up Korea's naval strength. He even invented a new kind of ship unlike anything known before. This new ship was called the kobuk-son, or turtle ship, and it was the world's first iron-clad warship.

The kobuk-son's deck was covered with hexagonal iron plates, as was the hull, to prevent enemy cannon shot from damaging the planking and to ward off fire from flaming arrows. It had 20 oars, for maneuverability and speed in battle. On the deck, iron spikes jutted up to discourage boarding attempts by enemy fighters. A dragon's head figurehead on the bow concealed four cannon that fired iron shrapnel at the enemy. Historians believe that Yi Sun-shin himself was responsible for this innovative design.

With a much smaller fleet than Japan's, Admiral Yi racked up 10 crushing naval victories in a row through use of his turtle ships, and his brilliant battle tactics. In the first six battles, the Japanese lost 114 ships and many hundreds of their sailors. Korea, in contrast, lost zero ships and 11 sailors. In part, this amazing record was also due to the fact that most of Japan's sailors were poorly-trained former pirates, while Admiral Yi had been carefully training a professional naval force for years. The Korean Navy's tenth victory brought Admiral Yi an appointment as the Commander of the Three Southern Provinces.

On July 8, 1592, Japan suffered its worst defeat yet at the hands of Admiral Yi and the Korean navy. In the Battle of Hansan-do, Admiral Yi's fleet of 56 met a Japanese fleet of 73 ships. The Koreans managed to encircle the larger fleet, destroying 47 of them and capturing 12 more. Approximately 9,000 Japanese soldiers and sailors were killed. Korean lost none of its ships, and just 19 Korean sailors died.

Admiral Yi's victories at sea were not simply an embarrassment for Japan. The Korean naval actions cut off the Japanese army from the home islands, leaving it stranded in the middle of Korea without supplies, reinforcements, or a communication route. Although the Japanese were able to capture the old northern capital at Pyongyang on July 20, 1592, their northward movement soon bogged down. 

Rebels and Ming

With the tattered remnants of the Korean army hard-pressed, but filled with hope thanks to Korea's naval victories, the ordinary people of Korea rose up and began a guerrilla war against the Japanese invaders. Tens of thousands of farmers and enslaved people picked off small groups of Japanese soldiers, set fire to Japanese camps, and generally harried the invading force in every possible way. By the end of the invasion, they were organizing themselves into formidable fighting forces and winning set battles against the samurai.

In February 1593, the Ming government finally realized that the Japanese invasion of Korea posed a serious threat to China as well. By this time, some Japanese divisions were battling with the Jurchens in what is now Manchuria, northern China. The Ming sent an army of 50,000 which quickly routed the Japanese from Pyongyang, pushing them south to Seoul. 

Japan Retreats

China threatened to send a much larger force, some 400,000 strong, if the Japanese didn't withdraw from Korea. The Japanese generals on the ground agreed to withdraw to the area around Busan while peace talks were held. By May of 1593, most of the Korean Peninsula had been liberated, and the Japanese were all concentrated in a narrow coastal strip on the southwestern corner of the country.

Japan and China chose to hold peace talks without inviting any Koreans to the table. In the end, these would drag on for four years, and emissaries for both sides brought false reports back to their rulers. Hideyoshi's generals, who feared his increasingly erratic behavior and his habit of having people boiled alive, gave him the impression that they had won the Imjin War.

As a result, Hideyoshi issued a series of demands: China would allow Japan to annex the four southern provinces of Korea; one of the Chinese emperor's daughters would be married to the Japanese emperor's son; and Japan would receive a Korean prince and other nobles as hostages to guarantee Korea's compliance with Japanese demands. The Chinese delegation feared for their own lives if they presented such an outrageous treaty to the Wanli Emperor, so they forged a much more humble letter in which "Hideyoshi" begged China to accept Japan as a tributary state.

Predictably, Hideyoshi was incensed when the Chinese emperor replied to this forgery late in 1596 by granting Hideyoshi the bogus title "King of Japan," and giving Japan status as a vassal state of China. The Japanese leader ordered preparations for a second invasion of Korea.

Second Invasion

On August 27, 1597, Hideyoshi sent an armada of 1000 ships carrying 100,000 troops to reinforce the 50,000 who remained at Busan. This invasion had a more modest goal - simply to occupy Korea, rather than to conquer China. However, the Korean army was much better prepared this time, and the Japanese invaders had a tough slog ahead of them.

The second round of the Imjin War also began with a novelty - the Japanese navy defeated the Korean navy at the Battle of Chilcheollyang, in which all but 13 Korean ships were destroyed. In large part, this defeat was due to the fact that Admiral Yi Sun-shin had been the victim of a whispered smear campaign at court, and had been removed from his command and imprisoned by King Seonjo. After the disaster of Chilcheollyang, the king quickly pardoned and reinstated Admiral Yi.  

Japan planned to seize the entire southern coast of Korea, then march for Seoul once more. This time, however, they met a joint Joseon and Ming army at Jiksan (now Cheonan), which held them off from the capital and even began to push them back toward Busan.

Meanwhile, the reinstated Admiral Yi Sun-shin led the Korean navy in its most astonishing victory yet at the Battle of Myongnyang in October of 1597. The Koreans were still trying to rebuild after the Chilcheollyang fiasco; Admiral Yi had just 12 ships under his command. He managed to lure 133 Japanese vessels in to a narrow channel, where the Korean ships, strong currents, and rocky coastline destroyed them all.

Unbeknownst to the Japanese troops and sailors, Toyotomi Hideyoshi had died back in Japan on September 18, 1598. With him died all will to continue this grinding, pointless war. Three months after the warlord's death, the Japanese leadership ordered a general retreat from Korea. As the Japanese began to withdraw, the two navies fought one last great battle at the Noryang Sea. Tragically, in the midst of another stunning victory, Admiral Yi was hit by a stray Japanese bullet and died on the deck of his flagship. 

In the end, Korea lost an estimated 1 million soldiers and civilians in the two invasions, while Japan lost more than 100,000 troops. It was a senseless war, but it did give Korea a great national hero and a new naval technology - the famous turtle ship.

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Szczepanski, Kallie. "The Imjin War, 1592-98." ThoughtCo, Apr. 5, 2023, Szczepanski, Kallie. (2023, April 5). The Imjin War, 1592-98. Retrieved from Szczepanski, Kallie. "The Imjin War, 1592-98." ThoughtCo. (accessed June 6, 2023).