Toyotomi Hideyoshi's disastrous attempt to conquer Korea for Japan

Japan only just had emerged from over a century of civil conflict, during which samurai clans fought for control over the country.

After he rose to power following the assassination of Oda Nobunaga by defeating rival commanders and consolidating control, Hideyoshi imposed authority over the daimyōs and replaced decentralised warfare with central control.

To preserve the loyalty of his warrior class and prevent internal unrest, he planned an overseas campaign that would justify continued military mobilisation and offer new spoils.

He also proclaimed his intention to conquer China within two years and sent letters to surrounding kingdoms that demanded submission.

In one instance, he addressed the Spanish authorities in the Philippines, insisting they recognise Japanese supremacy, though no tribute was paid and his demands were rejected. 

Under the Joseon Dynasty, Korea relied on Confucian principles to maintain social structure and centralised rule.

The court prioritised diplomacy and learning over militarisation. While its army remained largely unmodernised, its navy had adopted advanced ship designs.

The panokseon, a sturdy warship with a raised deck and equipped with heavy cannon, gave Korea an advantage in coastal warfare.

Some early engagements also featured the geobukseon, or "turtle ship," an armoured warship with spiked plating and enclosed decks that offered innovative protection, though it was not a true 'ironclad' in the modern sense. 

Meanwhile, Ming China viewed the region as part of its traditional area of influence.

It possessed vast resources together with a large standing army and maintained a well-developed administrative system.

Although Chinese officials dismissed early Korean warnings, the scale of Japan’s advance eventually forced the Ming court to act. 

In the spring of 1592, Japanese troops landed at Busan and captured the port on May 23 after intense hand-to-hand fighting.

Hideyoshi’s generals deployed large invasion forces, with Japanese records claiming up to 150,000 men transported over time in successive waves.

These were arranged in divisions that advanced along the major routes linking the southern coast to the capital.

Reinforced with matchlock firearms and well-drilled infantry, they overwhelmed Korean defenders in successive engagements. 

From the riverbanks near Seoul to the central plains of the peninsula, Japanese forces moved rapidly.

Their commanders used roads built for administrative purposes and seized towns before defenders could organise.

King Seonjo abandoned the capital and fled north, leaving the royal court in disarray. 

Elsewhere, Admiral Yi Sun-sin coordinated a naval counterattack in coastal waters south of the invasion routes.

His fleet, which consisted of armoured panokseon warships, engaged Japanese transports and raiding squadrons.

He delivered a string of victories that slowed Japanese resupply efforts and disrupted the movement of reinforcements by employing superior mobility and heavier cannon.

He also took advantage of Korea’s narrow straits and hidden inlets to launch ambushes and surprise attacks. 

Eventually, the Korean court appealed to its traditional ally under growing pressure.

From Liaodong, the Ming court assembled an expeditionary force under General Li Rusong, who crossed into Korea during the winter of 1592.

In January 1593, his army of around 43,000 men retook Pyongyang after a hard fought battle that forced Japanese troops into retreat. 

Soon afterwards, Chinese forces encountered defended Japanese positions along the roads that led south toward Seoul.

They used siege artillery and well trained troops to push back enemy lines. Korean guerrilla bands, known as uibyong, also attacked Japanese columns from forested terrain and took back rural districts with local support.

Some units included seungbyeong, or monk-soldiers, who had been called up to defend Buddhist temples and nearby towns. 

At the same time, Admiral Yi continued to inflict heavy losses on the Japanese fleet.

Just like before, from small hidden bays and narrow straits, he launched surprise attacks that stopped supply convoys and prevented sea resupply.

His knowledge of local geography and use of combined cannon fire kept the Japanese navy on the defensive. 

Following the failure to hold central Korea, Japanese commanders fell back to southern bases and waited for further orders.

In Kyoto, Hideyoshi sent diplomats such as Konishi Yukinaga to the Ming court and demanded recognition of his control over Korea.

The Chinese offered ceremonial titles and suggested a peaceful settlement, but poor communication and false reporting made any agreement almost impossible to achieve.

In fact, Hideyoshi was falsely informed that the Ming court had accepted his terms and granted him royal status. 

Elsewhere in the north, Korean officials worked to rebuild civil authority and restore local administration.

Military officers restructured the army and expanded recruitment. New training camps began drilling soldiers in firearms and fortification techniques under the guidance of Chinese advisers. 

Meanwhile, Hideyoshi prepared for another assault. He demanded fresh levies from his daimyōs and reissued mobilisation orders.

Although fewer troops were raised than in 1592, the intention remained the same: to compel Korean surrender and force the Ming court to accept Japanese control in the region. 

In the summer of 1597, Japanese forces launched a second invasion, which landed along the southern coast and recaptured several towns.

Their goal shifted from full conquest to simply holding strategically valuable territory.

Japanese divisions abandoned plans to drive north toward the capital and concentrated on holding key fortresses and disrupting Korean supply lines.

Kato Kiyomasa, one of Hideyoshi’s most aggressive commanders, led the most successful, but brutal, campaigns through several provinces. 

In response, Korean and Ming armies coordinated resistance across several provinces.

Ming generals brought larger forces than in the first war and deployed cavalry and artillery to support Korean infantry.

Korean commanders, for their part, were now more experienced and better supplied, and were able to execute joint campaigns with improved precision. 

Shortly after he returned to command, Admiral Yi prepared for a major defensive stand.

He reestablished discipline among his sailors and restructured his fleet. In October 1597, he achieved his most famous victory at the Battle of Myeongnyang, where he used the tidal currents of a narrow channel, where he trapped and destroyed a much larger Japanese fleet. 

Eventually, the entire course of the war shifted when Toyotomi Hideyoshi died in September 1598.

His council of regents hid the news while they fixed politics at home. From Osaka, they issued orders to withdraw all forces from Korea and instructed commanders to abandon their positions. 

Across southern Korea, Japanese garrisons took apart their defences and burned supplies before they departed.

Korean and Ming forces advanced into empty strongholds and took back land without fighting.

However, no official agreement ended the war. Instead, it simply concluded with a quiet withdrawal. 

In the aftermath, Korea faced a national disaster. From destroyed cities to burnt farmland, the devastation was extensive.

Tens of thousands of civilians had been killed or enslaved. Parts of the national archives, including some volumes of the Annals of the Joseon Dynasty, were destroyed and had to be carefully rebuilt with surviving copies that were stored in remote locations.

Ming China, though victorious, had drained its treasury and weakened its army.

Back home in Japan, they returned to focus on internal control under Tokugawa rule, having gained practically nothing from the foreign expedition.

Ultimately, Hideyoshi’s attempt to dominate East Asia ended in ruin, and the memory of what was called the Imjin War remained in memory for generations.