The Imjin War: Japan's Sixteenth-Century Invasion of Korea and Attempt to Conquer China

by Samuel Hawley

  Such was not the case with muskets. Subsequent letters sent home from Korea by Japanese commanders would repeatedly state that they had more than enough swords and spears and arrows and did not want any more. What they needed were more muskets. To the Koreans the invading Japanese seemed well equipped with these feared weapons; one source opined they had 300,000 of them.[119] This is a very unlikely figure. The exact number is not known, but inferences can be made from correspondence of the period. In his 1591 letter of requisition to the Kyushu daimyo Shimazu Yoshihiro, for example, Hideyoshi ordered that he arm 1,500 of his men with muskets, 1,500 with bows, and 500 with spears.[120] Considering that Shimazu contributed about 10,000 men to the invasion, and that no more than half this number were full-time fighting men (the rest would have been engaged primarily in logistical support work),[121] this would suggest that fifteen percent of his total force, or thirty percent of his fighting strength, was equipped with personal firearms. Applying this percentage to the total number of 158,800 Japanese soldiers sent to Korea, a more realistic total of roughly 24,000 muskets is obtained—still a crushing advantage over the Koreans, who had seen their first “dog leg” only the year before.

  The various companies in Hideyoshi’s army were highly self-contained. Each was led by a daimyo, thirty-eight in all. In every instance musket-bearing ashigaru formed the vanguard. It was their job to decimate enemy lines and, it was hoped, send them into retreat so that spear and sword units could then rush forward and finish them off with a minimum of resistance. Cavalry units no longer existed as such. Daimyo and their top men rode horses; the ashigaru foot soldiers, as their name implied, walked. Bringing up the rear, finally, were the porters and support staff, that long logistical train that comprised at least half of every unit. These were the nameless men who built fortifications, set up camp, hauled food and gear, cooked meals, and did the hundred and one other jobs that were indispensable to the operation of any army in the field. In the coming invasion of Korea, however, even the lowliest porters and laborers in the Japanese army would prove themselves quite capable of handling a sword or musket and joining in the fight, and so they must be factored into the fighting strength of each unit as quasi-soldiers rather than noncombatants.

  These various companies were grouped into nine contingents. In the upcoming invasion the nine would occasionally work in coordination like divisions in a modern army to achieve some particular objective, but more often they would operate independently of one another. Indeed, the individual companies comprising each contingent would at times split up and go their own way. They were able to do so because Hideyoshi’s invasion force, unlike the armies of China and Korea, was not a centrally controlled national army commanded by a government-appointed hierarchy of officers, but rather a loose confederation of regional armies that were in effect “owned” by the wealthy daimyo lords who raised, armed, and led them. Each of these daimyo had sworn allegiance to Hideyoshi and was committed to using his army to achieve Hideyoshi’s goals, but beyond that he expected and was accorded a good deal of independence in how he organized and employed his men. It was a system that generally worked well for the Japanese. It meant, however, that Hideyoshi himself was the only one capable of effective supreme command; the only one with the clout to override the independent spirits of the daimyo and exercise control over the entire invasion force. The taiko knew this. It was therefore his intention to cross over to Korea in the wake of his advancing armies, reestablish his headquarters in Seoul once that city had been taken, and from there orchestrate the subsequent move on Beijing.

  The Japanese army gathering at Nagoya in the spring of 1592 was the largest army ever assembled in Japan up to that time, and the most professional; a well-organized, well-supplied, and well-equipped war machine designed to project massive killing power. There was not an army anywhere in the world at that time that was superior to it, or probably even its equal. Contemporary armies in Europe were well equipped with muskets and artillery, but they came nowhere near to equaling the immensity of Hideyoshi’s. By way of comparison, the Spanish armada that sailed for England in 1588 consisted of 30,000 men aboard 130 ships—one-fifth the size of the taiko’s 158,800-man expeditionary force. There was in fact only one other country in the world that could raise an army of even 100,000 men, and that was Ming China. But the Ming, for all their manpower, did not have state-of-the-art arquebuses, only old-fashioned fo-lang-chi guns and a scattering of poorly made muskets that tended to blow up in your face.

  There was, however, one chink in Hideyoshi’s armor, one weakness that would prove telling if not fatal later on: his navy. Navies had not played much of a role in Japan’s wars of unification, and consequently Japan’s naval development lagged behind Korea’s. Ships were used during the sengoku period mainly to transport troops, or on rare occasions as floating platforms upon which land battles could be extended offshore. In such engagements the usual objective was to decimate the men aboard enemy vessels with arrow and musket fire and then, when their ranks had been sufficiently weakened, to move in close for boarding to finish off survivors. Naval warfare, in other words, was conducted much like warfare on land: the idea was to kill enemy soldiers, not sink enemy ships.[122]

  There were exceptions. In 1576 Oda Nobunaga approached Osaka with his army aboard a flotilla of three hundred small craft with the intention of storming the Mori stronghold. The Mori’s own fleet met him in the harbor and in the ensuing battle seriously mauled Oda’s floating army. To break the Mori’s naval superiority, Nobunaga ordered one of his vassals, a co-opted pirate leader named Kuki Yoshitaka, to construct seven heavy ships, armored in part if not wholly in iron, that would be impervious to the Mori’s arrow and musket fire. He returned to Osaka with a squadron of these vessels in 1578 and succeeded in annihilating the Mori’s conventional fleet of light, wooden ships—the first recorded use of “iron ships” in the history of naval warfare.[123]

  This amazing victory seems to have had little impact on Hideyoshi, who was a top Oda general at that time and undoubtedly acquainted with the battle and the shipbuilding activities of his fellow vassal Kuki. Instead of attempting to develop the idea of an armored ship impervious to enemy fire, he seems to have remained mired in 1592 in the old notion of the ship as a floating platform for land troops.

  To transport his invasion force across to Korea, Hideyoshi ordered the maritime daimyo of Kyushu, Shikoku, and Chugoku (the western end of Honshu) to supply ships at a rate of two large vessels for every 100,000 koku of annual revenue. This core of large ships would have been augmented by several hundred existing smaller craft, fishing boats, and Inland Sea cargo ships. The resulting motley armada totaled approximately seven hundred vessels of various sizes, capable of carrying anywhere from just a few tens of men up to several hundred. To man them, fishing villages were required to provide ten sailors for every hundred households.

  These seven hundred vessels were not warships. They were transports that were intended to ferry soldiers across to Tsushima Island and then on to Pusan. They were lightly built, they afforded the men on board little or no protection, and they had no onboard artillery other than the few cannon that were being transported to Korea, which in all likelihood were stowed as cargo and not mounted for use at sea. They were, in short, vulnerable to attack by the Korean navy. To provide this flotilla some measure of protection, Hideyoshi ordered Kuki Yoshitaka—the same man who had commanded Nobunaga’s iron ships back in 1578—to oversee the construction of several hundred warships in the Bay of Ise on central Honshu’s Pacific coast. The largest of these, of the atakebune class, were thirty-three meters long and carried a crew of one hundred and eighty. Smaller were the sekibune and the kohaya classes. Although heavier than the transport ships they would be convoying, all three of these classes were still significantly lighter than the warships of the Korean navy, and not as maneuverable. They also carried fewer cannon: the atakebune, the largest and presumably the most heavily armed, had only three guns, whereas the mos
t lightly armed Korean battleship carried at least twelve.

  Hideyoshi also attempted to augment his navy with European ships. The idea had been in his mind from at least as early as May 1586, when he expressed a desire to the Jesuit Gaspar Coelho to charter two Portuguese men-of-war for his planned conquest of China. He was prepared, he said, to pay handsomely for the vessels, and would additionally have churches built all across China and order the entire population converted to Christianity. Father Coelho, thinking Hideyoshi was merely daydreaming, agreed offhandedly to provide the ships (despite standing orders from his superior not to interfere in local politics). Hideyoshi reportedly was delighted. This intriguing twist never materialized, however, despite Hideyoshi’s repeated requests to the Portuguese in the months leading up the war.[124]

  To man the warships of his navy, Hideyoshi ordered a number of maritime daimyo on Honshu and Shikoku to raise a total of 9,450 men, a rather light force considering the gargantuan army they would be expected to protect. The daimyo at the head of these men would be his “admirals.” They included Kuki Yoshitaka with 1,500 men, Todo Takatora (2,000), Wakizaka Yasuharu (1,500), Kato Yoshiaki (1,000), the Kuwayama brothers, Ichiharu and Masaharu with 2,000, and the Kurushima brothers, Michiyuki and Michifusa, with 700.[125] Some of these daimyo admirals were the heirs of the wako pirates who had terrorized the coasts of Korea and China up until the mid-1550s. Kuki Yoshitaka, for example, was of the same Kuki family that had launched raids from its lair on the Kii peninsula, while the Kurushima brothers descended from an Inland Sea wako chief. Such men were to be found elsewhere in the invasion force as well: Matsuura Shigenobu was a descendent of the same Matsuura clan that had given rise to the wako back in the thirteenth century; Goto Sumiharu was daimyo of the once notorious Goto Islands. While lawless wako pirates may no longer have existed in Hideyoshi’s Japan, the tradition thus was in a sense being kept alive as their now respectable descendants prepared to return to Korea in the biggest wako raid East Asia had ever seen.

  This, then, was Hideyoshi’s navy. It consisted of a large number of vessels, probably in the neighborhood of one thousand all told, but many were small, light transport ships with little or no fighting capability.[126] Even the warships were not particularly strong or well armed, and were commanded by daimyo with little or no naval experience, men who regarded naval warfare as land warfare afloat. Whether any of this concerned Hideyoshi is not known. We may surmise from his unsuccessful attempt to secure Portuguese ships that he considered his homegrown fleet less than invincible. On the other hand, he had not encountered significant naval resistance during his unification of Japan and probably did not expect to encounter any now, at least none that his ships could not handle.

  When the Kuki completed construction at Ise of the warships they had been required to build, Hideyoshi ordered them to move the fleet forward to his invasion headquarters at Nagoya, a journey of six hundred kilometers. From there it would accompany the taiko’s troop-laden transports across the strait to Pusan, lashing any Korean warship that ventured too close with a withering barrage of musket fire. That, anyway, was the plan.

  * * *

  Some sort of Japanese aggression was by this time widely anticipated in Korea. Ambassador Hwang Yun-gil, who had led the “goodwill mission” to Kyoto in 1590, had warned the court in Seoul that Hideyoshi posed a real threat, and many believed him. Even Vice-Ambassador Kim Song-il, who officially contradicted everything Hwang said and sparked the dispute between the Eastern and Western factions over whether or not there would be a war, confided to fellow Easterner Yu Song-nyong, now Minister of the Left,[127] that he had not really meant what he said. “I also feel that there is no alternative, as in the end the Japanese will unleash war,” he said. “But Hwang’s words were too pessimistic, and those inside and outside the court will become bewildered and lose their self-control. That is the reason why I said what I did.”[128]

  A fight was clearly coming with Japan. Hwang and the Westerners knew it. Kim and the Easterners knew it. A full-blown invasion that would devastate the country and permanently cripple the dynasty was not expected. But something resembling a large wako pirate raid was. The Koreans had faced Japanese pirates on many occasions before, most recently in the 1550s. The official histories of the Choson dynasty and preceding Koryo dynasty made it clear that when Korea was unprepared, these marauders were capable of doing tremendous harm, but that with preparation they could be dealt with. So clearly preparation was required. But what sort of preparation? And how much? And where to start?

  And what, in the meantime, should they tell Ming China?

  The China issue arose upon the return of the Korean mission from Kyoto in the spring of 1591, bearing the letter from Hideyoshi that left no doubt as to his intentions: he wanted to invade the Middle Kingdom and usurp the Celestial Throne. To the Koreans, Hideyoshi’s conceit was not only shocking, it was distasteful and obscene, and they were sorry they had ever exchanged envoys with him. Some members of the government now began to worry that China might think Korea had stepped beyond the bounds of the vassal–sovereign relationship by establishing relations with this Japanese barbarian without prior Ming approval, and feared that Beijing would be angry if it found out. “I am afraid,” said Prime Minister Yi San-hae, “that unless we conceal the fact, the Imperial Court will consider it was a criminal act for us to have carried out an exchange of envoys with Japan on our own volition.”

  Minister of the Left Yu Song-nyong did not agree. He argued that, as a loyal vassal of China, Korea was duty-bound to inform the Ming court of these latest developments and to warn it of the looming threat posed by Japan. “Indeed,” he added, “if those robbers really plan to invade China, others may inform the Emperor. Then the Celestial Court will unjustly suspect that we have concealed this business because we are in accord with the Japanese.”

  That was in fact exactly what was going on. By early 1591 word had already reached Beijing from elsewhere of Hideyoshi’s plans for conquest, first from envoys dispatched by King Shonei of the Ryukyu Islands, then from separate messages sent by two Chinese men residing in Japan. Beijing awaited corroborative reports from Seoul, but the months passed and no word arrived, leading some to question the loyalty of Little China, and even to suspect that it might be somehow in league with Japan. Only Prime Minister Xu Guo, a former ambassador to the Choson court, stood up for Korea. “Korea has remained loyal to sadae [serving the great],” he said. “It cannot be in agreement with the rebellious spirit of the Japanese. Just wait awhile.”[129]

  Beijing waited. And the Koreans continued to talk. In the meantime, Inspector-General Yun Tu-su, who agreed with Yu Song-nyong about the need to inform the Ming of the threat posed by Japan, privately wrote a report of his own and gave it to Kim Ung-nam, the ambassador of a tribute mission then about to depart for Beijing, with orders to deliver it as soon as he arrived, a breach of protocol that would subsequently earn Yun a stint in exile in the countryside. This vague document, which made no mention of the envoys that had been exchanged between Korea and Japan but only of “rumors” the Koreans had heard, reached the Ming capital not long after the Ryukyuan envoy sent by King Shonei and thus eased some of the suspicion the Chinese were starting to feel. Mistrust would linger, however, for it would not be until early 1592 that an official embassy finally arrived from Korea with what was purported to be a full account of Hideyoshi’s threats and demands and the events that had transpired over the past four years. And even then the Koreans felt it necessary to gloss over many of the details, particularly concerning the envoy exchanges, for they continued to fear that these would be misinterpreted as evidence of their truckling with Japan.[130]

  While the question of whether to inform China was being debated in the halls of power in Seoul, attention was also being directed to the state of the nation’s defenses. They were not in good shape. Something had to be done to shake up the military if an invasion was to be met.

  Korea’s military in 1592 was base
d upon an organizational framework that had existed since the beginning of the Choson dynasty two centuries before. It had been modeled to a great extent upon the defense structure of the preceding Koryo dynasty, which in turn had followed the general pattern of the military of Tang-dynasty China.[131] The nation’s army consisted of five “guards”: a Forward Guard for Cholla Province in the southwest; a Rear Guard for Hamgyong Province in the northeast; Left Guard for Kyongsang Province in the southeast; Right Guard for Pyongan Province in the northwest; and Middle Guard for the central provinces of Hwanghae, Kyonggi, Kangwon, and Chungchong. Each of these five guards maintained army garrisons and naval bases in their respective regions of the peninsula, plus an auxiliary force in Seoul to defend the capital and to serve as a national army in time of crisis.[132]

  Overall command of Korea’s armed forces was in the hands of the General Headquarters of the Five Guards in Seoul. Beneath this body were the nation’s top generals. These generals did not actually command armies. It was the practice in Choson Korea to keep them all based in Seoul, under the controlling hand of the government and well removed from the armies they were ostensibly responsible for. This was done to protect the nation from the threat of insurrection. The Koryo dynasty had fallen in this very manner back in 1388, when General Yi Song-gye marched his army on the capital, usurped the king, and subsequently founded the Choson dynasty with himself as monarch. Once he was secure in power, Yi initiated the practice of separating generals from their armies to ensure that no one henceforth would be able to do what he had done and overthrow his own dynasty. Generals would be placed at the head of armies only when national security was threatened and a military response required. Otherwise they would be kept in Seoul.