Repercussions

Korea lost perhaps a million people out of a population of around ten million, and the physical destruction was worse than the death toll. Cultivated land fell by roughly two thirds; famine and epidemic followed the armies and outlasted them. Palaces, temples, and archives burned — some of them lit by Koreans themselves before the Japanese arrived. Whole provinces were depopulated. The Joseon dynasty survived, but the country it governed took the better part of a century to rebuild, and arguably never recovered the confidence it had before 1592.

Joseon Korea had not fought a serious war in two centuries and had built a state that actively disdained soldiering — Confucian scholar-officials outranked generals by definition, and the military examination was the lesser path. The army was largely a paper establishment, the fortresses were unrepaired, and gunpowder infantry was something that happened elsewhere. When the court sent two envoys to assess Hideyoshi in 1590 they returned with opposite reports along factional lines, and King Seonjo believed the one that required no spending. Three weeks after the landing the Japanese were in Seoul.

Yi Sun-sin fought at least twenty-three naval engagements against a numerically superior enemy and won every one, including Myeongnyang, where thirteen ships beat a fleet of over 130 in a tidal strait. He did it by refusing the war his enemy had prepared — Japanese ships were built to close and board, so he built gun platforms and never let them close. His own government arrested, tortured, and demoted him mid-war on a fabrication planted by Japanese agents, then handed him back the wreckage of the fleet his replacement had lost in one night. He is Korea's national hero without qualification, and no serious rival has emerged in four centuries.

The Japanese beat every Korean army they met and took every city they wanted, and it did not matter. Their plan required supplying the northern advance by sea up the west coast; Hansan Island closed that route in August 1592 and it never reopened for long. A hundred and fifty-eight thousand men then had to be fed overland through a country whose peasants had risen against them in the *uibyeong* righteous armies and whose monasteries had raised warrior monks. The advance halted where it stood, not because it was defeated but because it could not eat — one of history's cleanest demonstrations that logistics beats tactics.

Ming China intervened because Korea was the shield of Beijing, and it worked — Li Rusong's artillery blew the Japanese out of Pyongyang and the northern provinces were retaken in days. It also cost something like ten million taels of silver that the treasury did not have, at the same moment the dynasty was fighting rebellions in Ningxia and the south-west. The Ming never recovered financially. Historians routinely list the Korean campaign among the causes of the collapse that let the Manchus take Beijing in 1644 — a dynasty of nearly three centuries fatally weakened by defending a neighbour it could not afford to lose.

Japan gained not one square metre of territory and lost its ruling house. The invasion killed or exhausted the western daimyō who fought it, drained the treasury, and — crucially — kept Tokugawa Ieyasu at home in the east, intact, while his rivals wore themselves out in Korea. Hideyoshi died in 1598 worrying about his five-year-old son; Sekigahara followed in 1600, with the Konishi–Katō feud from Korea splitting the Toyotomi camp down the middle, and the house was extinct by 1615. Hideyoshi launched the war partly because he could not safely disband his army. It destroyed his dynasty anyway.

A century of civil war left Hideyoshi, on unifying Japan in 1590, holding the largest and most battle-hardened military establishment on earth — hundreds of thousands of professional warriors who had known nothing but war, a third of them armed with arquebuses Japan had been refining since the 1540s. Peace made them useless and dangerous simultaneously; sending them home was more likely to produce a rebellion than a settlement. Korea was, among other things, somewhere to point them. The invasion is what happens when a state's military capacity outgrows any purpose it can be put to at home.

The Tokugawa took power in 1600 having watched the invasion destroy the house that launched it, and they drew the obvious conclusion: no more continental adventures. No Japanese army left Japan again for two hundred and fifty years. The shogunate went further and closed the country outright — expelling the Portuguese, restricting the Dutch to one artificial island at Nagasaki, banning Japanese subjects from going abroad on pain of death, and crushing Christianity. Sakoku had several causes and fear of Christian subversion was the loudest, but the strategic lesson underneath was Hideyoshi's: overseas expansion had bankrupted the treasury, killed the western daimyō, and ended the Toyotomi.

The Japanese carried off thousands of Korean craftsmen, and the potters most deliberately of all — the second invasion is still called the Pottery War in Japan. Satsuma ware and Arita porcelain were founded by abducted Korean families; the Chōsen potter Yi Sam-pyeong is credited with finding the kaolin that made Arita possible, and his descendants were still working the kilns generations later. Japanese porcelain then became a major export to Europe when the Ming collapse interrupted the Chinese trade. An enormous transfer of skill, extracted at gunpoint, that enriched the invader's culture for centuries and stripped the victim's.

Ryu Seong-ryong, forced from office on the day Hideyoshi died, went home and wrote the *Jingbirok* — an unsparing account of how his own government's factionalism, complacency, and contempt for military affairs had nearly destroyed Korea. He named the failures, including his own, so that they would not be repeated. It is one of the great works of political self-examination in any language and the principal source for the war. Copies were smuggled to Japan, where it sold well enough that the shogunate eventually banned its export — the Japanese were reading Korea's account of the war before Korea had finished absorbing it.

The war was decided by two incompatible naval doctrines meeting. Japanese warships were troop transports built to close, grapple, and board, crewed by the best boarders alive; Korean panokseon were strong flat-bottomed gun platforms carrying real cannon, and the geobukseon turtle ship added an iron-spiked roof that made boarding impossible. Yi simply never allowed the fight his enemy had trained for. It is the same lesson Europe was learning at exactly the same time — the Armada in 1588 was decided by the identical mismatch, English guns against Spanish boarders — arrived at independently on the other side of the world.

Korea drew the obvious conclusion from having been invaded through its ports by a neighbour it had failed to take seriously: trust nobody and let nobody in. The Manchu invasions of the 1620s and 30s confirmed it. Joseon turned inward for two and a half centuries, restricting foreign contact to tightly managed tribute missions and earning the name the Hermit Kingdom — a posture that preserved it for a long time and then left it catastrophically unprepared when Japan came back in the nineteenth century with steamships and a colonial project.

The Mimizuka in Kyoto — the ear mound, where tens of thousands of noses taken from Korean dead and living were buried under a monument — still stands, and Korean visitors still go. The war remains a live nerve in East Asian relations four centuries on: it is taught as the founding case of Japanese aggression in Korea, it colours every dispute over textbooks and apologies, and Yi Sun-sin's statue faces down the main avenue of Seoul. Hideyoshi gained nothing territorially and left behind a grievance that has outlasted his dynasty by four hundred years.