The Japanese Opening of Korea, 1876
Under the Tokugawa shoguns, when Japan was a closed nation, all trade with Korea had been mediated by the So clan in their capacity as the daimyo of Tsushima Island. Korea was largely closed to foreign trade as well (except for with China), and thus all Japanese traders were confined to a tiny enclave on the southern tip of Korea, near Pusan. Over time this very limited trade relationship had accumulated a variety of ritual elements - special ceremonies, protocols, seals, etc.
Following the Meiji Restoration of 1868, Japan began to seek out new trading opportunities with her Asian neighbors, especially in Korea. The Japanese sought to expand the Korean trade along Western "free trade" models and to normalize their relationship with the Korean government according to western precepts of "international law." The Korean court was perfectly happy with the status quo, however, and steadfastly rebuffed any deviation from the established procedures, refusing to parlay with any Japanese not from the So family and insisting upon calling the Japanese Emperor the same term they had used to refer to the shoguns. In 1873, the Meiji oligarchs briefly debated a military expedition to forcibly open Korea to expanded trade, but ultimately opted to continue with diplomatic overtures. Feathers on both sides continued to be ruffled, however, and tensions continued to rise.
These tensions finally erupted into violence in 1875. On September 20, the Un'yo, a Japanese naval vessel surveying the western coast of Korea, put ashore a landing party on the island of Kanghwa to request water and provisions. The Koreans chose to view this as a violation of their territory, and Korean shore batteries opened fire on the Un'yo. The Japanese response was swift and severe. The Un'yo returned fire on the batteries and landed an assault party on the island that torched several Korean houses and skirmished with Korean troops. The Korean soldiers, armed only with ancient matchlock muskets, were badly overmatched by the Japanese and their modern rifles, and 35 Koreans were killed.
The Japanese spent the next three months planning an appropriate response. In the meantime, they portrayed the incident to the public and the international community as a vicious, unprovoked attack by the Koreans on a peaceful survey mission in need of aid. While there is no direct documentary evidence of a conspiracy by the Japanese government to purposefully provoke an incident with the Koreans, the Japanese version of the story stretches credulity. It is difficult to understand why a Japanese naval vessal planned its provisioning so poorly as to run out of water and supplies, let alone to do so right at Kangwha Island, a key startegic point at the mouth the Han River guarding the western approach to the capital at Seoul. Moreover, the Un'yo mission was suspiciously dispatched just days after a Japanese diplomatic mission negotiating with Korean officials at Pusan was order to break off talks and return home.
The Japanese response to the Un'yo incident came in February. In a classic display of gunboat diplomacy reminiscent of Perry's opening of Japan 23 years earlier, ministers Kuroda Kiyotaka and Inoue Kaoru arrived at Kangwha Island along with three naval warships and a force of 1,200 soldiers. The suitably cowed Korean court was forced to agree to the Treaty of Kanghwa that granted the Japanese access to two more "treaty ports" in addition to Pusan, the right to put ashore in emergency for wood, water, and shelter, the right to survey Korean coasts, and the right of extraterritoriality. The Japanese deliberately modeled the treaty on the Treaty of Kanagawa that Perry had forced on them in 1854. Further negotiations granted Japanese traders a complete exemption from tarrifs, and most amazingly off all, allowed the Japanese to purchase Korean goods at face value with Japanese currency! Thus, at the same time Japanese diplomats were bitterly complaining to Western nations about the "unequal treaties" the West had forced on Japan, they evidently had no qualms forcing even more unequal treaties upon Korea.