Battle of Imjin River (1592)

Retreat of the King

In the Fall of 1592, King Seonjo left Hanseong shortly before the arrival of Japanese vanguard led by Katō Kiyomasa, which forded the Han River in what is today Yongsan. At this time, the Korean public already abandoned the king and the minister, and cooperation with the Japanese army was becoming more common. Moreover, when the reinforcing Ming army retreated, the people that suffered were the civilians. Gyeongbokgung had already become ashes before the Japanese army marched through the gates, and Korean slaves greeted them as a liberation army, and set fire to the building that kept the slaves' ledger. Following the sack of the city, Katō built an imposing Japanese castle on the Namsan mountain overlooking Seoul on what is today the site of the City Library. Seonjo and his court retreated north to Pyongyang and eventually China on foot while harassed by peasants who felt abandoned.

Reaching the Imjin, and hearing of Japanese pursuit, they forded the river at night. As it was dark, they decided to burn the pavilion near the Imjin ford. The burning pavilion provided enough light to allow the King's party to ford the river and reach Gaeseong by morning. Little did he know that the burning pavilion was the retirement home of Yi I the late prominent scholar who had strongly petitioned to strengthen national security by enlarging the armed forces to 100,000 men, only ten years before. Yi I was dead by this time, but his retirement home provided for the King's safe retreat across the Imjin.

Arrival of the Northern Border Cavalry

As the King reached Kaesong and continued north towards Pyeongyang, the northern cavalry from Hamgyeong province finally arrived. Being battle-hardened veterans of numerous border clashes against the Jurchens of Manchuria, the cavalry forces quickly moved to the Imjin River, where the forces of Katō Kiyomasa in pursuit of the king had camped on the southern bank, awaiting to ford the river. There the forces faced each other in a stalemate.

According to the primary Korean record, the Korean generals debated amongst themselves over the course of action they should take. Several generals argued, "We are numerous but much of our number is weak and inexperienced; we are relying heavily on the Northern Cavalries but they have just arrived after a long march and is tired, we should rest for a few more days to regather our strength before proceeding forward." But they were overruled and the lead general decided to engage the enemy.

Katō's attack

Knowing the Korean dependence on the Cavalry charge as opposed to infantry melee from Chungju, and realizing that the northern cavalry forces had yet to be exposed to Japanese arquebus fire, Katō decided to break the deadlock by drawing the Koreans into a trap. Sending a small force of light infantry ashigaru across the river, Katō caused the Koreans to gain unrealistic confidence, as they mowed down the ashigaru spearmen with ease in a single cavalry charge. Noticing that the charge was uncoordinated and sensing a disunity of command, Katō ordered a feigned general retreat towards the direction of Munsan from the southern banks of the Imjin.

Katō's victory

Seeing the Japanese in an apparent general retreat, one of the two co-commanders of the Cavalry decided to ford the river in pursuit. In the dry season the Imjin River is very shallow at various points which enabled the cavalry to cross without the use of barges. As the retreat drew them in, the Korean cavalry lost all semblance of order. The pursuit became disorganized, going uphill towards Munsan. The battle turned into another episode of the Battle of Chungju.

Once the bulk of Korean cavalry had entered the small valley leading from the Imjin ford to Munsan, Katō's arquebusiers opened fire. This had a devastating effect on the morale of the Korean cavalry. As with nearly all Korean forces, Korean cavalry had no experience with gunfire. The horses of the cavalry began to panic, bucking many of the riders. As the Koreans lay in confusion, the samurai infantry attacked from their hidden positions within the valley and began routing the Koreans. The Korean cavalry suffered many casualties in this melee while others attempting to escape drowned while trying to cross back north using deeper parts of the river. Amongst the Korean Generals Yu Geuk-ryang and Sin Hal were killed. The remaining co-commander of the Korean cavalry who had not crossed the river in pursuit, turned and escaped back to Hamgyeong province, and most or the remaining soldiers following suit. Katō Kiyomasa and his troops forded the Imjin unopposed, loaded with trophy armor and fine Korean horses.

Conclusion

The defeat of the Korean cavalry at the Imjin lay open the road to Pyeongyang. There were no effective Korean units or defended castles between the Imjin and the Chinese border. Hearing of the collapse of the Imjin line, King Seonjo abandoned Gaeseong and Pyeongyang and moved further north to Uiju, where he finally met up with the first Ming contingent from China. With Ming troops joining the vestiges of his Army, Pyongyang was retaken the next year, with Japanese retreating across the Imjin back to Seoul. Korea north of the Imjin river would never be occupied again by the Japanese until the First Sino-Japanese War (1894-1895).

The Imjin River today

The fording site today has a small castle wall-like structure on the riverbank to show the old ferry site. The northern bank is off limits to civilians. There is an "Old Ferry Restaurant" at the fording site. Yi's retirement home is now restored, and is further up slope from the restaurant to the East, adjacent to the highway. The northern bank is shallow and sandy, with a large beach. The southern bank is mostly cliffs.

In popular culture

This battle is celebrated in Activision's "Shogun: Total War" under "Imjin". The historical error in the game is that the Koreans have infantry forces only, while Japanese have balanced combined armed forces. Also the game shows the river having a bridge, which was not the case until the 20th century.