Why Satsuma Invaded Ryukyu in 1609

From Maritime Ryukyu, 1050–1650, by Gregory Smits (University of Hawaii Press, 2018), Kindle pp. 358-360:

The war of 1609 had several causes, but the overwhelmingly important one was Ryukyu’s refusal to serve as an intermediary between the Tokugawa bakufu and the Ming court. At this point, we have sufficient information to understand the basic reason for what might otherwise seem like an irrational policy. Shō Nei’s bending to pressure from Shimazu and Hideyoshi probably prompted an armed revolt in 1592. The Chinese decisions to hold the investiture ceremonies in Fujian and, later, to send a military official might well have been justifiable as wartime expedients. However, from the standpoint of the Ryukyuan court—Shō Nei, his supporters, and his enemies—such measures appeared to be a reprimand for Shō Nei’s having supported Hideyoshi’s invasion. The year 1593 was a turning point. After that, Shō Nei became determined never again to appear as an agent of any Japanese polity.

The massive Ming resistance to Hideyoshi’s invasions of Korea also played a psychological role. From a Ryukyuan perspective, it appeared that the Ming court would go to war for its tributary states. As we will see, leading Ryukyuan officials apparently became convinced that China would back Ryukyu in a military conflict, that Ryukyu was too geographically dispersed and remote for Shimazu successfully to launch an invasion, and that Ryukyu’s deity, Benzaiten, would protect the kingdom.

THE REGIONAL GEOPOLITICAL SITUATION AFTER 1598

Control of piracy was an issue of much concern during the late sixteenth century. Hideyoshi, Shimazu, and the council that succeeded Hideyoshi in 1598 issued prohibitions against piracy and demanded active cooperation by Ryukyu in this endeavor. Moreover, very soon after Hideyoshi’s death, Shimazu and other powerful lords in Japan sought to establish trade relations with Ming China. Shimazu may have come close to succeeding. The domain enlisted the Bōnotsu merchant Torihara Sōan to head an expedition to repatriate captured Ming general Máo Guókē. According to Satsuma’s account, Torihara traveled all the way to Beijing in 1600, and the Chinese court promised to send two ships to Satsuma each year. In 1601, the ships sailed, but pirates attacked and destroyed them in the vicinity of Iōjima in the Satsunan islands. Key details concerning these events are not clear.

For our purposes, the main point is that after Hideyoshi’s death leaders of Japan vigorously pursued paths to reestablish good relations with China, and the Shimazu lords understood the importance of this opportunity. Ryukyu’s location made it an integral part of the process. From the standpoint of Shimazu or Tokugawa Ieyasu, the ideal option was that Ryukyu actively cooperate in suppressing piracy and restoring Sino-Japanese trade. The less desirable option was to use coercive force in an attempt to compel such cooperation. Ryukyu’s continued resistance to Satsuma and bakufu entreaties to assist in restoring relations with Ming China eventually tipped the scales in favor of military action.