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

by Samuel Hawley

  Was “Little China” to be trusted?

  CHAPTER 6

  Preparations for War

  The wheels of Hideyoshi’s war machine began to turn in the summer of 1591. The first step was to establish a headquarters for his invasion force. Kyoto was out of the question; it was much too far from Korea to allow Hideyoshi any sort of direction of his invading armies. He would need to be on Kyushu, close to the action. The settlement of Nagoya[112]—present-day Karatsu—on the northern coast of Hizen Province was selected and work begun there on an enormous castle in November of that year. Tens of thousands of laborers were requisitioned from local daimyo, and under the guidance of Hideyoshi’s trusted general Kato Kiyomasa a tremendous fortified complex began to take shape, surrounded by a double ring of defensive moats and walls.[113] From here it would be just eight hours with a fair wind to the halfway island of Tsushima, then another six hours to Pusan on Korea’s southern tip.

  To raise his invasion army, Hideyoshi turned to the daimyo. Each would be required to supply a predetermined number of troops in proportion to size of his fiefdom through a system termed gunyaku, or required military service. This was how Hideyoshi had completed the conquest of Japan, by ordering vassal daimyo to contribute divisions to swell the ranks of his army. It was how he raised laborers for his great construction projects in and around Kyoto, the palaces, the temples, and the Great Buddha that was slowly taking shape. It was how he built his sprawling invasion headquarters at Nagoya in the space of a few months. And it would be how he would muster a quarter-million-man army for the invasion of Korea.

  When imposing military or labor levies, Hideyoshi made allowances for the distance over which daimyo had to transport their contributions. Daimyo nearest to the scene of an upcoming campaign or construction project were required to contribute relatively more, and those farther away relatively less. This system of sliding levies brought a degree of fairness to Hideyoshi’s requisitions, recognizing the fact that the farther a daimyo had to transport a contribution, the more it cost him. In raising his army for the invasion of Korea, Hideyoshi seems to have followed such a plan. It worked like this: the daimyo of Kyushu, being nearest to Nagoya and in turn Korea, were required to provide six men for every hundred koku of rice that their respective domains were estimated to produce annually; daimyo farther away in the western provinces of Honshu were required to send five men per hundred koku; daimyo even further away on central Honshu were burdened to a correspondingly lesser degree, down to as few as two men per hundred koku. A navy was assembled in a similar manner, with a sliding levy for ships being imposed on Kyushu, Shikoku, and western Honshu daimyo with coastal domains. Sailors to man these ships were rounded up from fishing villages along the coast of Kyushu and the Inland Sea, at a rate of ten men for every hundred households.

  Those are the broad strokes of how Hideyoshi raised his army. Upon closer examination, however, the picture is not so simple, and in fact is still not fully understood. To begin with there was the issue of tax exemptions. Daimyo who had rendered a particular service to Hideyoshi or who he otherwise favored were frequently rewarded with such exemptions in the form of having a portion of their domain declared tax free. In calculating troop requisitions for the coming invasion of Korea, Hideyoshi’s sliding levy scale was therefore applied only to the taxable portion of each daimyo’s domain. It seems fairly clear, moreover, that Hideyoshi’s relationship with each daimyo often entered into the equation as well. Those he could trust and over whom he exercised firm control could be handed levy requirements with little worry that they would resist or rebel. Those over whom his control was weak, conversely, had to be treated more circumspectly. There were quite a few such daimyo in Hideyoshi’s New Japan, men he had won over through negotiated settlement rather than decisive victory in battle. They tended to receive bigger tax exemptions and lighter military service demands, prompting some of their contemporaries to complain of the seeming arbitrariness of Hideyoshi’s troop levies.[114]

  The makeup of the invasion army assembling at Nagoya was therefore more complex than it might at first appear. The contributions sent by some daimyo, particularly long-time Hideyoshi allies, fit the sliding scale fairly well, while the contributions of others, particularly former enemies, did not. Kato Kiyomasa, for example, a native of Hideyoshi’s own hometown of Nakamura and one of his most trusted generals, sent a contingent of 10,000 men from his 200,000-koku fief in Higo Province on Kyushu, a relatively heavy contribution from a domain that apparently had almost no tax exemption. Shimazu Yoshihiro, on the other hand, provided a force of equal size from his much larger 559,530-koku domain in nearby Osumi Province, suggesting a tax exemption rate of roughly seventy percent for this former enemy of Hideyoshi’s, coaxed into the fold only after the latter’s Kyushu campaign of 1587. From the island of Shikoku, long-time Hideyoshi loyalist Fukushima Masanori sent a force of 4,800 men from his 200,000-koku domain in Iyo Province, a reasonable contribution considering the distance he had to transport it. Yet Chosokabe Motochika, the former lord of Shikoku who had prudently bowed to Hideyoshi upon the latter’s invasion of that island in 1585, sent just 3,000 men from his 220,000-koku fief in neighboring Tosa Province. Such discrepancies in contributions to the coming invasion reveal just how uncertain Hideyoshi’s grip was on the newly unified Japan. The coalition of daimyo he had assembled still needed careful tending to keep them subservient. They had to be pushed to serve Hideyoshi, but not pushed too far, and kept happy with promises of more land and more wealth. There was no longer any more land to be conquered in Japan. In 1591 he had it all. With his planned invasion, however, he expected to grab untold millions of continental koku, enough to keep his vassals happy and under his control for decades to come.[115]

  A staggering total of 335,000 men were mobilized nationwide in the spring of 1592 for the invasion of Korea. Of this number 235,000 were sent to invasion headquarters at Nagoya, and 100,000 were shifted about the country to strengthen areas left under-defended by the massive mobilizations. Of the 235,000 encamped in and around Nagoya Castle, 158,800 were earmarked to actually cross over to Korea. It was logistically impossible for Hideyoshi to send this entire force to Korea in one huge mass. Had he done so they would have starved. Instead he grouped the various daimyo-led units into nine separate contingents varying in size from 10,000 up to 30,000 men, the natural limit in the late sixteenth century to the size of a body of troops that could be kept fed and functioning in the field.[116] The daimyo commander of each of these units was provided with a map of the Korean Peninsula depicting its eight provinces and the three routes north. These maps were copies of one that So Yoshitoshi had acquired during his mission to Korea and presented to Hideyoshi. The taiko had taken it and painted each of Korea’s eight provinces a different color to distinguish them. Henceforth each province would be identified among the Japanese by its corresponding hue on this map of operations: Cholla-do was the “Red Country,” Chungchong-do the “Blue Country,” Kyongsang-do the “Green Country,” and so on.[117]

  At first glance this invasion army seems to have been composed of the variety of Japanese troops that one would expect Hideyoshi’s system of sliding levies to have yielded: 82,200 men, fifty-two percent of the total force, were from Kyushu; 57,000 (thity-six percent) were from Honshu; and 19,600 (twelve percent) were from Shikoku. It was a distribution that made sense: Kyushu bordered Korea, so Kyushu should contribute most; Honshu and Shikoku were farther away, so their contributions should be proportionally less. It would be wrong to infer, however, that Hideyoshi intended Kyushu troops to do fifty-two percent of the fighting, Honshu troops thirty-six percent, and Shikoku troops twelve percent. In examining the order of battle he drew up on April 24, 1592, a pattern emerges that reveals something of his domino strategy for the conquest of Asia.

  Konishi Yukinaga’s first contingent, Kato Kiyomasa’s second, and Kuroda Nagamasa’s third were charged with spearheading the invasion of Korea. This force consisted entirely of men from
Kyushu and its offshore islands. They would sail first from Nagoya to Tsushima, reassemble on that island, then push on to Pusan. Once on Korean soil their mission was to drive north to Seoul as fast as they could. Contingents four through seven would then follow to reinforce the advance armies for the continued push to the Chinese border. These four contingents were also composed mainly of units from western Japan: the fourth and sixth were made up entirely of Kyushu men, the fifth came from the island of Shikoku, and the seventh from western Honshu. Contingents eight and nine, consisting of men from western and central Honshu, would in the meantime remain in reserve on their respective island bases at Tsushima and Iki, crossing to Korea as conditions warranted. A further force of 75,000 provided by Tokugawa Ieyasu, Date Masamune, Uesugi Kagekatsu, and other Honshu daimyo, would remain stationed at invasion headquarters at Nagoya. Hideyoshi did not plan to send this reserve into action; their job was to protect Nagoya in the event of a Chinese counterattack. Finally, a force of some 100,000 men was moved down from the Tokai and Kinai regions of eastern Honshu to protect the capital of Kyoto, which the Nagoya mobilizations had left inadequately defended.

  Kyushu men, therefore, while comprising slightly more than half of Hideyoshi’s invasion force, would do most of the actual fighting; Honshu divisions would back them up or remain at Nagoya as a “home guard.” This troop utilization represented a new approach to conquest for Hideyoshi, a domino strategy designed to extend his rule overseas.

  During his unification of Japan in the 1580s, Hideyoshi used the armies of subject daimyo to swell the ranks of his own personal force, intimidating foes with the immensity of his power by amassing armies in excess of one hundred thousand men. There comes a point, however, when an army is big enough—indeed, where it can become no bigger for want of resources to supply it. With all Japan now his, Hideyoshi had reached that point. There was no need to dispatch an even bigger and even more costly force to take the kingdom of Korea; one hundred and fifty thousand men would do. Now he would use his long left arm, Kyushu, to reach across the sea and take Korea. While Kyushu troops were doing the heavy work on the peninsula, forces from Honshu would back them up. Once the Koreans were subdued, they would be drawn into Hideyoshi’s planned Asian conquest, supplying manpower and materiel for the continued push into China. When the region around Beijing was under Hideyoshi’s control, he would require the Chinese to raise the forces necessary to extend his reach into the southern provinces of that vast Middle Kingdom. The southerners would then be used to subdue the west; the westerners would be sent against the Thais, Burmese, and Cambodians; and presumably the far westerners would then be commissioned to make the final push into India.

  Figure 4: Japanese Invasion Forces, May 1592 [118]

  COMMANDER

  (Domain*)

  MEN

  TOTAL

  1ST CONTINGENT

  Konishi Yukinaga

  (Higo, Kyushu)

  So Yoshitoshi

  (Tsushima)

  Matsuura Shigenobu

  (Hizen, Kyushu)

  Arima Harunobu

  (Hizen, Kyushu)

  Omura Yoshiaki

  (Hizen, Kyushu)

  Goto Sumiharu

  (Goto Islands)

  7,000

  5,000

  3,000

  2,000

  1,000

  700

  18,700

  2ND CONTINGENT

  Kato Kiyomasa

  (Higo, Kyushu)

  Nabeshima Naoshige

  (Hizen, Kyushu)

  Sagara Nagatsune

  (Higo, Kyushu)

  10,000

  12,000

  800

  22,800

  3RD CONTINGENT

  Kuroda Nagamasa

  (Buzen, Kyushu)

  Otomo Yoshimune

  (Bungo, Kyushu)

  5,000

  6,000

  11,000

  4TH CONTINGENT

  Shimazu Yoshihiro

  (Osumi, Kyushu)

  Mori Yoshinari

  (Buzen, Kyushu)

  Takahashi Mototane

  (Hyuga, Kyushu)

  Akizuki Tanenaga

  (Hyuga, Kyushu)

  Ito Yuhei

  (Hyuga, Kyushu)

  Shimazu Tadatoyo

  (Hyuga, Kyushu)

  10,000

  2,000

  2,000*

  14,000

  5TH CONTINGENT

  Fukushima Masanori

  (Iyo, Shikoku)

  Toda Katsutaka

  (Iyo, Shikoku)

  Chosokabe Motochika

  (Tosa, Shikoku)

  Ikoma Chikamasa

  (Sanuki, Shikoku)

  Hachisuka Iemasa

  (Awa, Shikoku)

  Kurushima Michiyuki

  (Iyo, Shikoku)

  Kurushima Michifusa

  (Iyo, Shikoku)

  4,800

  3,900

  3,000

  5,500

  7,200

  700**

  25,100

  6TH CONTINGENT

  Kobayakawa Takakage

  (Chikuzen, Kyushu)

  Kobayakawa Hidekane

  (Chikugo, Kyushu)

  Tachibana Munetora

  (Chikugo, Kyushu)

  Takahashi Saburo

  (Chikugo, Kyushu)

  Tsukushi Jonosuke

  (Chikugo, Kyushu)

  10,000

  1,500

  2,500

  800

  900

  15,700

  7TH CONTINGENT

  Mori Terumoto

  (Aki, western Honshu)

  30,000

  30,000

  8TH CONTINGENT

  Ukita Hideie

  (Bizen, western Honshu)

  10,000

  10,000

  9TH CONTINGENT

  Hashiba Hidekatsu

  (Mino, central Honshu)

  Hosokawa Tadaoki

  (Tango, central Honshu)

  8,000

  3,500

  11,500

  158,800

  * Total for Takahashi, Akizuki, Ito and Shimazu

  ** Total for Kurushima Michiyuki and Michifusa

  Hideyoshi, then, did not envision a vast Japanese army fanning out across China, down into Indochina, over the Himalayas, and onto the sweltering plains of the subcontinent. Only his rule would spread in this manner, carried farther and farther by locally levied native armies serving an inner core of Japanese troops. A purely Japanese army, or more precisely a Kyushu army, would only begin the process. It would act as the first domino in the cascade, a cascade that would extend Hideyoshi’s rule to the farthest reaches of Asia.

  * * *

  The Japanese army of invasion that had assembled at Nagoya by April of 1592 was a formidable force, the Darwinian end product of more than a century of civil war that saw traditional military thought give way to more practical methods of killing. The way of the samurai was still considered glorious, quality horseflesh was still appreciated, and the finely crafted katana sword was still a highly valued thing. But they were no longer the mainstay in Japanese warfare. The lightweight arquebus had changed all that. It was relatively cheap to manufacture. It shot farther than a bow, and more important, packed a greater armor-piercing punch at the closer distances preferred in battle, usually one hundred meters or less. It was easy to use; an uneducated farmer could be taught to handle one effectively in just a few weeks. It did not demand the same degree of intestinal fortitude to wield in battle as did “short weapons” such as the sword and spear; Japanese arquebusiers commonly did their work from behind protective cover. And it gave a soldier an overwhelming, even shocking, advantage. As Oda Nobunaga’s stunning victory in the Battle of Nagashino demonstrated, no amount of samurai skill or courage could prevail against a curtain of flying lead balls. In that seminal 1575 engagement, three thousand Oda foot soldiers stood behind a wooden paling with muskets in hand and patiently mowed down charge aft
er charge of traditionally armed adversaries. After that Japanese warfare was never the same.

  Samurai therefore did not constitute a very large portion of Hideyoshi’s invasion army in 1592, nor were traditional cavalry units much in evidence. The use of horses was largely confined to daimyo commanders and their officers, custodians of the samurai tradition with their superbly crafted armor, fierce war masks, and exquisite swords. The bulk of the army was now the ashigaru, the foot soldier. These were mainly farmers and fishermen recruited and trained by daimyo from their respective domains, men like Hideyoshi’s own father Yaemon. They would have been a rough lot, poorly educated and for the most part unable to read. They would not have traveled much; the march to Nagoya alone was likely the greatest journey many had ever taken. In looking ahead to the crossing to Korea, fear was probably the dominant emotion—fear of dying in a strange and distant place. Most probably wanted nothing more than to get the job done and return to their families. But on the other hand all the talk circulating through the camps of Korean and Chinese wealth must have been alluring, conjuring up visions of cities overflowing with booty, just sitting there for conquering Japanese soldiers to haul away home.

  The ashigaru were equipped with swords and spears and bows in addition to lightweight muskets. A portion of these traditional weapons came from the various sword hunts Hideyoshi had conducted over the previous few years to disarm the peasantry of Japan. His edict of 1589 had declared that all weapons turned in would be used in the construction of the Great Buddha in Kyoto, but the stipulation that swords be collected together with their scabbards indicates that they were to be stored for future use, not melted down to make nails and bolts. One source states that a total of 5,000 battle axes, 100,000 long swords, 100,000 short swords, 100,000 spears, and 500,000 daggers were collected through sword hunts and daimyo requisitions and transported to Nagoya. This figure is undoubtedly inflated, but it is safe to say that Hideyoshi’s army was generously supplied with traditional weapons.