The Invasion of Ryukyu — Satsuma's Expedition Against the Ryukyu Kingdom and the Surrender of Shuri Castle

In the 3rd month of Keichō 14 (1609), a force led by the chief retainer Kabayama Hisataka, acting on the orders of Satsuma domain lord Shimazu Iehisa (Tadatsune), invaded the Ryukyu Kingdom. Some 3,000 troops sailed from Yamakawa harbor (present-day Ibusuki, Kagoshima Prefecture). They passed through Amami Ōshima, Tokunoshima, and Okinoerabujima, landed at Unten harbor on the northern part of Okinawa Island, then advanced from north to south via Nakijin and pressed toward Shuri Castle. In the early part of the 4th month of Keichō 14 (1609), Shuri Castle surrendered, and King Shō Nei came down from the castle and submitted. Shō Nei was taken to Satsuma, where he later had an audience with the shogun Tokugawa Hidetada in Edo. About two and a half years later, he was finally permitted to return home. From this event onward, the Ryukyu Kingdom maintained an unusual international position, the so-called "dual subordination to Japan and China," in which it was subordinate to both Japan (the Satsuma domain and the Edo shogunate) and China (Ming and Qing), and it kept this position until the end of the Bakumatsu period.

Background to the Invasion

Since the medieval period, the Ryukyu Kingdom had built its own foreign relations centered on tributary relations with Ming China, while also repeatedly engaging in trade and exchange with the Shimazu clan of Satsuma. Their relationship was complex, mixing conflict and cooperation. For example, the Shimazu held the role of controlling trade by issuing red-seal licenses for ships sailing from the mainland to Ryukyu. When Toyotomi Hideyoshi launched the invasions of Korea (the Bunroku and Keichō campaigns, 1592–1598), the Shimazu also demanded that Ryukyu bear the cost of provisions and military expenses, but Ryukyu's response is said not to have fully met the Shimazu's expectations. Even after Tokugawa Ieyasu established the Edo shogunate following the Battle of Sekigahara, there was a plan to use Ryukyu as an intermediary in restoring diplomatic relations with Ming, which had been cut off, but this was not realized. Combined with these long-standing grievances, the Shimazu's aim of expanding their rights in foreign trade led to the Ryukyu expedition being planned with the shogunate's approval. The Shimazu's view that Ryukyu had long stood in a vassal-like relationship to them is also said to have been used as the justification for the expedition. Within Satsuma, discontent over burdens following the Korean campaigns also simmered, and it has been pointed out that the expedition had a domestic political meaning as well: displaying military prestige abroad. The Edo shogunate's tacit approval of the expedition is said to have also aimed at confirming the Shimazu's power in the waters south of Kyushu, while indirectly probing for a way to repair relations with Ming.

From Departure at Yamakawa to Landing at Unten Harbor

On the 26th day of the 2nd month of Keichō 14 (1609), the Satsuma force gathered at Yamakawa harbor and received an inspection by the domain lord, Iehisa. On the 4th day of the 3rd month of Keichō 14 (1609), in the hour of the Tiger, the force set out after waiting for a favorable wind. Organized into a fleet of more than 80 vessels, it sailed south under the command of commander-in-chief Kabayama Hisataka and deputy commander Hirata Masumune. On the 7th day of the 3rd month of Keichō 14 (1609), in the hour of the Monkey, they reached Fukae-ga-ura on Amami Ōshima and subdued it, gaining control of the island without meeting major resistance. After staying on Ōshima for a while, they set sail on the 20th day of the 3rd month of Keichō 14 (1609) and reached Tokunoshima the same day. On the 24th day of the 3rd month of Keichō 14 (1609), they left Tokunoshima, passed through Okinoerabujima, and on the 25th day of the 3rd month of Keichō 14 (1609), in the early evening, entered Unten harbor on the northern part of Okinawa Island. About three weeks after leaving Yamakawa, the expedition moved south island by island. It met resistance from some islanders on Tokunoshima, but because the Ryukyuan side had no unified defenses at the time, it proceeded without large-scale battles. Although Amami, Tokunoshima, and Okinoerabujima were all within the territory of the Ryukyu Kingdom, they were remote areas far from the royal capital of Shuri and had no defense system of their own. This was one factor that allowed the Satsuma force's rapid advance south.

From the Occupation of Nakijin Castle to the Surrender of Shuri Castle

On the 27th day of the 3rd month of Keichō 14 (1609), two days after landing at Unten harbor, the Satsuma force reached Nakijin Castle, a key stronghold in the north of the main island. The castle had already been abandoned, and the Satsuma force set fire to it. Nakijin Castle had once been the royal castle of the Hokuzan kingdom and had kept its status as the northern stronghold even after the unification of Ryukyu in the 15th century, so this occupation is said to have carried symbolic significance as well. The force continued south, and on the 1st day of the 4th month of Keichō 14 (1609), in the hour of the Sheep, it reached Naha harbor and showed a posture of encircling Shuri Castle. Peace negotiations were held with the Ryukyuan side, and an agreement was reached in which the regent, Prince Gushichan, and the sanshikan (the three-member council of state) and others were offered as hostages. On the following day, the 2nd day of the 4th month of Keichō 14 (1609), the hostages were formally handed over. Judging that it was difficult to continue resistance, the Ryukyuan side accepted the negotiations, and soon King Shō Nei came down from Shuri Castle, and the castle surrendered. Shuri Castle itself did not become the scene of a fierce siege. The course of events, in which the castle surrendered after advance and intimidation, through negotiations and the submission of hostages, is remembered as one of the characteristics of this campaign.

King Shō Nei's Surrender and Transfer to Edo

After the surrender, King Shō Nei was taken to Satsuma and set out for Kagoshima on the 15th day of the 5th month of Keichō 14 (1609). In the following year, Keichō 15 (1610), he had an audience with the retired shogun Tokugawa Ieyasu at Sunpu, and on the 28th day of the 8th month of Keichō 15 (1610), he had an audience with the second shogun, Tokugawa Hidetada, at Edo Castle. It was the first time a Ryukyuan king had directly met the shogun and the retired shogun, and for the Satsuma domain it carried great political significance as a way of showing the shogunate its achievement in conquering Ryukyu. The audience at Edo Castle was framed as Ryukyu coming to court as a foreign state. From then on, the Satsuma domain continually used the Edo nobori (Ryukyuan missions to Edo) as a diplomatic ceremony to stage loyalty to the shogunate. After returning to Kagoshima, Shō Nei was asked to sign a written oath (kishōmon) stating that Ryukyu had been a vassal state of the Shimazu since ancient times and pledging allegiance. He was also asked to sign the Fifteen Regulations (Okite jūgo-kajō), which set out the basic policy for governing Ryukyu, and he accepted both. The Fifteen Regulations set the framework of Ryukyuan governance thereafter, including placing foreign trade under Satsuma's control.

Return Home and the Establishment of the "Dual Subordination" System

Shō Nei was actually permitted to return to Ryukyu in Keichō 16 (1611), about two and a half years after he had been taken away. In the meantime, the Satsuma domain used a land survey to set the assessed yield of the territories from Okinawa Island southward at a little over 89,000 koku. It established a system of levying annual tribute to the Shimazu based on this figure. Foreign trade also came under Satsuma's supervision. Later, in Kan'ei 5 (1628), a Satsuma resident magistrate's office (zaiban bugyō-sho) was established in Naha. On the other hand, the Ryukyu Kingdom itself was not dissolved. The Shō family's royal line was allowed to continue, and the tributary relationship with Ming (and later Qing) was maintained as it was. As a result, Ryukyu maintained a distinctive political position of subordination to both Japan (the Satsuma domain and the Edo shogunate) and China, the so-called "dual subordination to Japan and China," for about 260 years until the bakumatsu period. For the Satsuma domain, this system functioned as a mechanism for securing the practical benefits of trade with China via Ryukyu. For the Edo shogunate, it continued to have value as a channel for obtaining foreign information. The Ryukyu Kingdom thus passed through the early modern period within a dual structure: nominally keeping its independence while being placed under the Satsuma domain's control financially and militarily.

Sword Culture in Ryukyu and Contact Under Satsuma Rule

In the Ryukyu Kingdom, the treasure swords handed down in the Shō family, the royal house, have been prized as symbols of royal authority. The three famous swords, Chiyoganemaru, Jiganemaru, and Chatan Nakiri, were each passed down through generations in the Shō family. Among them, Jiganemaru is a wakizashi dating back to the 15th century, and it is said that in the early 16th century it was presented to King Shō Shin by the chieftain of Miyako Island, Nakasone Tuyumya. Rather than weapons for actual combat, these swords were kept at Shuri Castle as ceremonial treasures that made royal authority visible. Today they are held by the Naha City Museum of History as part of the Materials Related to the Shō Family, Kings of Ryukyu, and they have been designated National Treasures. After the 1609 invasion, the Satsuma resident magistrate's office was permanently established in Naha in Kan'ei 5 (1628). The culture of sword-wearing and swordcraft that had developed in the warrior society of mainland Japan then came into contact with Ryukyuan society in a form different from before. That said, no record has been found that Satsuma confiscated the Shō family's treasure swords themselves. It is thought that, together with the continuation of the royal line, these swords too continued to be held as treasures symbolizing Ryukyuan royal authority. The contrast between the sword culture of Satsuma's warrior class, which valued actual combat, and the treasure-sword culture of Ryukyu, which valued ceremony and royal succession, can be said to reflect, from the perspective of swords, one aspect of the power relations this invasion brought about. The Ryukyu invasion is also an event that, in the history of the Japanese sword, brings to light once again the diversity of how swords have been used. They have functioned not only as weapons in actual combat but also as symbols displaying royal authority and social status.